Malcolm Staves' Notebook for Wireless

MStavesME203137-160226-22.pdf

Title

Malcolm Staves' Notebook for Wireless

Description

A notebook used by Malcolm Staves for recording his training notes on Wireless.

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Coverage

Language

Format

One notebook with handwritten annotations

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This content is available under a CC BY-NC 4.0 International license (Creative Commons Attribution-NonCommercial 4.0). It has been published ‘as is’ and may contain inaccuracies or culturally inappropriate references that do not necessarily reflect the official policy or position of the University of Lincoln or the International Bomber Command Centre. For more information, visit https://creativecommons.org/licenses/by-nc/4.0/ and https://ibccdigitalarchive.lincoln.ac.uk/omeka/legal.

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Identifier

MStavesME203137-160226-22

Transcription

Form 619.

ROYAL AIR FORCE.

Notebook for use in Schools.

[underlined] aeroplanes. [/underlined]

[underlined] QBB [/underlined]

[underlined] QTE [/underlined]

[underlined] QTF [/underlined]

[deleted] Q [/deleted]

[calculations]

[page break]

[blank page]

[page break]

[unreadable number] 591418. STAVES. M. E.

[underlined] WIRELESS. [/underlined]

Form 619.

ROYAL AIR FORCE.

Notebook for use in Schools.

[page break]

[blank page]

[page break]

[underlined] The Atomic Theory. [/underlined]

All matter is divided into 2 classes, elements [missing word/s] compounds. There are 3 kinds of matter, solids, liquids & gasses. The smallest particle of a substance which can still be identified as that substance is called a molecule. Molecules can still further be split into atoms. The atoms of elements substances are all of identical form, while those of compounds are found to be a mixture of elements atoms. Basically all substances are composed from 1 or more of 92 element atoms. Thus water compound substance is found to be a combination of the element gasses H2 & O2.

1 M of water - 2 atoms of H. 1 Atom of O.

[diagram]

[underlined] Simple Atom Hydrogen. [/underlined]

[diagram]

[underlined] Helium Atom Complex. [/underlined]

[diagram]

[underlined] Complex Atom [/underlined] with no free Electrons.

[underlined] Electrons [/underlined] are negative charges of electricity

[underlined] Protons [/underlined] are positive charges of electricity

[page break]

[missing word/s] Charges repell [sic] each other

Unlike Charges attack each other

Proton is 1800 times heavier than electron [symbol] any influence inserted on the atom moves only the Electron. Thus a part of electricity is an orderly flow of electrons.
Substances containing many free electrons such as copper are good conductors. Substances with no free electrons, or very few are good insulators.

[underlined] Conductors [/underlined]
Gold
Silver
Copper
Aluminium
Lead
Platinum
Water

[underlined] Insulators [/underlined]
Mica
Rubber
Ebonite
Porcelain
Dry Wood

In order to obtain a current of electricity it is necessary to have a complete circuit and a driving force or pressure.
[underlined] Electromotive Force [/underlined] or E.M.F. is the total pressure which is attempting to drive the electrons round a circuit.
[underlined] Units of Measure [/underlined]
[underlined] COULOMB [/underlined] is unit of electrical quantity & is = to 10 19 electrons.
The unit of current is the Ampere & 1 Amp is [missing letter/s] aid to flow when 1 coulomb passes any given

[page break]

point in a circuit inset & E.M.F. is brought [missing word/s] existence when chemical, mechanical or lead energy is converted into electrical energy eg both rail - mechanical generator.
The E.M.F. or pressure is measured in volts. Unit of resistance is the OHMS, it is said that the resistance of the conductor is ohms if an applied pressure of 1 volt causes 1 amp to flow.
The resistance of a conductor is directly proportional to its length & inversely proportional to its cross section
[underlined] OHMS LAW [/underlined]
The current in a circuit is directly proportional to the [deleted] length [/deleted] voltage applied & inversely proportional to [deleted] its [/deleted] the resistance.

[diagrams] [calculations]

[underlined] E.M.F. [/underlined] is the total pressure which is attempted to drive electrons round the circuit.
[underlined] Potential Difference [/underlined] is the voltage measured between any 2 points in a circuit.
[underlined] Power [/underlined] means the instantaneous rate of doing [missing word/s]
[underlined] Energy [/underlined] is the amount of work done.

KILO = 1.000= K MILLI = 1/1000 = m
MEGA = 1,000,000 = m. MICRO = 1/1,0 [missing numbers]

[page break]

[underlined] [missing letters] egative Potential [/underlined] is always referred to as low potential.
[underlined] Positive Potential [/underlined] as high potential

[diagram]

[underlined] KIRCHOFFS LAW [/underlined] is that sum of Potl Diff's of a series circuit will always equal the E.M.F. The voltage across [deleted] of [/deleted] a resistance in a circuit bears the same relationship to total voltage or EMF, that resistance bears as [deleted] it [/deleted] [deleted word] to total resistance.
[underlined] A Series Circuit [/underlined] is a circuit in which there is only one path for the current to take & it flows through each part in turn [symbol] the current is the same at each or every point in the circuit.
R = R1 + R2 + R3.
[underlined] Resistances in Parrallel [sic]. [/underlined]
I a parallel circuit the current has one or more alternative paths. The Voltage across each path is is also equal to the full E.M.F.

[diagram] [calculations]

[missing word/s] [missing letters] sistances are placed in parallel the total Res is[missing word/s] the least.

[page break]

[underlined] Batteries. [/underlined]
[underlined] Primary Cells [/underlined]

[diagram]

[underlined] LE CLANCHÉ CELL [/underlined]

[underlined] A Primary Cell [/underlined] is a cell in which the production of an E.M.F. is the primary effect. It can only be re-charged by replenishing exhausted chemicals.
[underlined] Le Clanché Cell. [/underlined] The chemical action which takes place in this cell causes hydrogen bubbles to form on the positive plate. These bubbles insulate the carbon rod & prevent the flow of electrons from the negative plate. To prevent this, a porous pot is placed round the carbon rod & is filled with manganese dioxide, which being rich in Oxygen absorbs the Hydrogen & turns into water. As Mang. Dioxide is a very poor conductor it is mixed with powdered carbon to improve its conductivity.
[underlined] Disadvantages. [/underlined]
1. Spillable.
2. Not Easily Portable
3. Bulky
4. No E.M.F.
5. No Capacity.

[page break]

[underlined] Dry Cell. [/underlined]

[diagram]

P.D. 1.5 Volts
Internal Resistance .1 [symbol]

[page break]

[underlined] Dry Cell. [/underlined] The dry cell is a development of [missing word/s] leclanché cell. The pitch at the top makes the [missing word/s] air-tight and prevents evaporation of the moisture in the electrolyte. Once the chemicals have dried up the cell is useless.
The action of the chemicals on the Zinc container will very often eat a hole right through, thus allowing the paste to dry up. Many of the manufacturers coats the inside of the container with mercury, this acts on the zinc, and coats the inside of the case with pure zinc and the chemicals do not act on it. [deleted word] They actually only act on the impurities in the zinc.
[underlined] Inert Cell. [/underlined]

[diagram]

Resistance .1 [symbol]
[underlined] Potential Difference 1.5v [/underlined]
This cell can be stored a considerable time and is especially [deleted] used [/deleted] suited for use in the tropics When required for use the container is filled with distilled water through the vents in the [missing word/s] After leaving for an hour or so the cell is [missing word/s] for use. As a general rule unused [missing word/s] should rattle. If cell has been used [missing word/s] will be stuck to the sides and will no [missing word/s]

[page break]

[underlined] Measuring Instruments. [/underlined]
[underlined] Hot Wire Type. [/underlined]

[diagram]

[underlined] The Ammeter [/underlined] The ammeter is a device for measuring current and is connected in series in the circuit. Any resistance in series adds to the total resistance of the circuit and thus alters the current value. Therefore for the purpose of accuracy a ammeter is constructed with as low restistance [sic] as possible.
[underlined] The Voltmeter [/underlined] is a device for measuring the difference of pressure between the extremes of the circuit, and so is connected in parrelel [sic] of the circuit. Since any additional parrelel [sic] of resistance lowers the [deleted] power [/deleted] value of the total resistance of the circuit to the value of less than the least. the voltmeter has a high resistance as possible so that circuit conditions are not upset.
[underlined] NB. [/underlined] Never connect an ammeter as a voltmeter, or vice versa.

[page break]

[underlined] Cables in Use in the RA.F. [/underlined]
R.AF. cables must not have a volts drop of [missing word/s] more than .1 volt per yard [deleted] by [/deleted] when carrying a full circuit. e.g. A 7 amps cable carrying full load has a volts drop of .1 volts per yard [symbol] the cable must have a resistance of .0143 ohms per yard.
[underlined] R.A.F. Sizes. [/underlined] 4 amp 7 amp 19 amp 37 amp & 64 amp.
The number of cores are indicated by the following prefaces. - une en try quadra quinte sexta septo.
[underlined] Covering. [/underlined] Rubber is used for flexibility next to the core, and is then covered by one of the following - flex, proof, sheath, cel, met, plug.
For high currents we use a cable with large core and then insulation. For high voltage we use small core and thick insulation.
[deleted word] [underlined] Colour Code of Aircraft Cables. [/underlined]
[underlined] Red [/underlined] - W/T. [underlined] Green [/underlined] - Inter. Comm. [underlined] Blue [/underlined] -Ignition
[underlined] Yellow [/underlined] - General Electrical Wiring [underlined] White [/underlined] - Bomb Release.
[underlined] Grey [/underlined] - Undercarriage Control [underlined] Black [/underlined] - Replacements

[underlined] Rheostat [/underlined] is a variable resistance & is used to vary the current flowing in a circuit

[diagram]

[page break]

[underlined] A Potentiometer [/underlined] is used for varying voltages.

[diagram]

[underlined] VOLTMETER TYPE 3-0.30. [/underlined] This type of voltmeter is of the moving coil class, & has a centre zero scale. It covers 2 ranges - 0 to 3 volts and 0 to 30.

[diagrams]

The 2 air springs are recorded in opposite directions (have equal tension) [deleted] so [/deleted] & are adjusted so that when needle is at [symbol] position tension on each will be equal.
Used very extensively for testing accumulators.

[diagram]

[underlined] Type "E" Testmeter. [/underlined] This testmeter can be used for testing voltages from [symbol] to 2000 volts for reading current from [symbol] milliamps to 20 amps. It can also

[page break]

be used for measuring ohms. The battery for this purpose is contained in the back of the instrument. and is a dry cell of 1.5 volts. These ranges are selected by means of a small switch on the face of the instrument which works in conjunction with a number of sockets into which the leads are plugged. By plugging into these sockets we bring into circuit the required series or shunt resistance that is necessary to dispose of the extra voltage or current in the circuit being tested.

[diagram]

meter should always be used face upwards
Mark [underlined] Z [/underlined] is used for adjusting needle on dial

[page break]

[duplicate page]

[page break]

[underlined] Secondary Cells. [/underlined]
I a sec cell the primary effect is a chemical action, the secondary effect is the production of an E.M.F.

[diagram]

[underlined] CHARGED CONDITION [/underlined]
Accumulators are made with lead grids forming the plates, the positive being filled with red[deleted] d [/deleted] lead & the negative plate being filled with [underlined] Litharge [/underlined] paste. By inserting these plates into the Electrolyte of Diluted Sulphuric Acid, and then passing a current through them a chemical change takes place and the paste in the positive plates becomes [deleted] red [/deleted] lead peroxide & the negative plate becomes spongy lead making it fully charged./
[underlined] Chemical Action. [/underlined]
From fully [underlined] charged [/underlined] to fully [underlined] discharged [/underlined] condition
(a) [underlined] Positive Plate [/underlined] (b) [underlined] Electrolyte [/underlined] (c) [underlined] Negative Plate. [/underlined]
(a) Lead Peroxide (b) Diluted Sulphuric A. (c) Spongy Lead
(a) Lead Sulphate (b) Water (c) Lead Sulphate
Reverse process for F. Dis-charged to F. Charged

[page break]

[underlined] Series [/underlined] 3 Accumulators

[diagrams]

Total 6.6 volts Capacity remains the same as one cell
[underlined] Parallel [/underlined]
[diagrams] Voltage 2.2 volts. Capacity 30 ah
[underlined] Capacity [/underlined] is the measurement of the ability of an acc. to store electrical energy. It is measured in
[underlined] Ampere Hours[/underlined]

[underlined] Ampere Hour. [/underlined] If an acc. has a rated [deleted letters] capacity of 10ah. it means that you could either take a current of 10 amps for 1 hr or a current of 1 amp per hour for 10 hrs. The size of the plates determine the capacity of an acc. The larger the plates, the larger the capacity.
[underlined] The 10 Hour Rate. [/underlined] is that steady current which will discharge a fully charged acc. (S.G. 1.270 Voltage 2.1 on load). to a discharged condition (G.S 1.150 Voltage 1.8 on load) in a period of 10 hours.
[underlined] Uses of the 10 hour rate [/underlined]to enable satisfactory comparisons to be made between the storing abilities of different accs. It may be used in the absence of makers instructions as a safe charging rate.
[underlined] Specific Gravity of Electrolyte. [/underlined] (based on 1 ac of [missing words] weighing 1 gramme.) Fully charged condition 1 [missing words] Discharged condition 1.150. [underlined] Voltage [/underlined] F. charged [missing words] 2.2 volts. F. charged acc [underlined] on [/underlined] load 2.1 volts. Dis [missing words] on load 1.8 volts. Accumulators should always [deleted words]

[page break]

on load, otherwise the internal resistance will cause false readings to be obtained.
The internal resistance of an acc. increases as it becomes discharged, owing to the formation of lead sulphate in the plates.
[underlined] Capacity. [/underlined] The useful life of an acc. in an aircraft is as long as the cell retains 3/5ths of its rate of capacity [underlined] ie [/underlined] a 12 volt 40 amp ph acc is not to be used in aircraft after its capacity falls to 24 A.H. To determine this a quarterly capacity test is carried out.
[underlined] RAF. Accumulators. [/underlined]

(a) Voltage (b) A.H (c) TYPE OF CASE (d) TYPE of VENT (e) USE (f) CHARGING RATE (g) AIR or GRD USE

(a) 2v (b) 7 (c) Celluiod [sic] (d) Unspillable (e) Wave Meters (f) .75 (g) NOT USED IN AIRCRAFT
(a) 2v (b) 14 (c) Type "B" (d) Unspillable (e) Heating Valve Filaments (f) 1.5 (g) USED IN AIRCRAFT
(a) 2v (b) 20 (c) Type "B" (d) Unspillable (e) Heating Valve Filaments (f) 2. (g) USED IN AIRCRAFT
(a) 2v (b) 90 (c) Glass (d) Stopper Type (e) Heating V. Filaments on heavy duty Receivers (f) 9 (g) NOT USED IN A/C
(a) 6v (b) 20 (c) Type "B"(d) Stopper Type (e)Heating the Filaments of Transmitters (f) 2 (g)USED IN A/C
(a) 6v (b) 80 (c) Moulded Case (d) Stopper Type (e) Motor Transport. (f) 8 (g) NOT USED IN A/C
(a) 12v (b) 15 (c) TYPE "B" [deleted] Moulded Case [/deleted] (d) Stopper Type (e) [deleted] 12v Battery [/deleted] Aircraft Electrical System. (f) 3 (g) used in [unreadable] A/C
(a) 12v (b) 25 (c) TYPE "B" (d) Stopper Type (e) A.E.S. (f) 2 (g) Medium Bombers.
(a) 12v (b) 40 (c) TYPE "B" (d) Stopper Type (e) A.E.S. (f) 4 (g) Heavy Bombers.

An Acc for use in an aircraft must have a Type "B" Case & an u/s Vent
[missing words] 480 & 480A are forms issued by RAF on Care [missing words] maintenance of accs.

[page break]

[underlined] Care of Accumulators. [/underlined]
[underlined] Initial Charge [/underlined]
1. Check case for cracks & make sure that seals over vents are unbroken.
[deleted] 2. [/deleted] Read the makers instructions.
2./ Break the seals & fill with an Electrolyte of the correct S.G. usually 1.270.
3./ Allow to stand for 12 hours to enable Electrolyte to soak into plates.
4./ Top up with acid of the same S.G. to make up for the soakage. (In Type B Accs this will be 3/16ths above the plates).
5./ Charge continuously [deleted] fo [/deleted] at correct rate, usually 10 hr rate, for about 16hrs. or until cells maintain signs of full charge, for 5 hours.
6./Discard the Electrolyte & refill with acid of the correct S.G.
7./ Give the acc. a short freshening charge.
[underlined] Indication of Charge [/underlined]
On charge the voltage should be approx 2.8v & S.G. 1.270.
These figures should remain constant for a period of 5hrs, and 1 hr on subsequent charges.
If you test a fully charged acc. on load, voltage should be 2.1v approx & 1.270 S.G.
When fully charged an acc's positive plate [missing word/s] a chocolate brown & the negative plate a [missing word/s]
Discharged acc. on load shows 1.8v approx. [missing word/s]
SG. H50. Both positive & negative plates [missing word/s] a greyish colour.

[page break]

[underlined] Charging. [/underlined]
1./ Clean Terminals, smear with mineral jelly & top up with distilled water to correct level (If acid has been spilt replace with acid of the same S.G.)
2/ Connect a charging board + to + - to - , allowing 3v for each cell, this means that on the normal type of board 12 2v cells can be connected to 1 bank.
3/ Charge at proper rate until fully charged. The charging rate constantly needs adjusting as the cells become more & more charged.
4/. Wipe the acc. & replace vent. (This should have been placed lightly in hole during charging. This allows gases to escape, but prevents acid splashing all over the tops of the accs.).
(In the RAF accs. are always connected to the charging board in series.)
[underlined] Inspection of Accs. before fitting into Aircraft. [/underlined]

1./ Make certain that the case is Type B and is not cracked or burnt. 2./ Check that it has unspillable vent, see that vent is not cracked or any holes stopped up. /make sure that rubber washer is in good condition.
3./ Check the level of the Electrolyte, it should not be more than 3/16th of an inch above the seperators [sic]. A higher level will interfere with the action of the u/s vent. [deleted] Then check the voltage [/deleted]
Replace u/s vent & screw down tightly. Discharge [missing word/s] for 5 mins at 10hr rate, then check voltage. [missing word/s] should not be less than 2volts for a cell on load [missing word/s] testing an acc. always test each cell seperately [sic].

[page break]

[underlined] Common Faults. [/underlined]

(a) Faults (b) Causes (c) Effects (d) Cure

(a) [underlined] Sulphation [/underlined] The hardening of lead sulphate which forms on both plates during discharge

(b) 1/ Discharge below 1.8 volts on load
2/ Persistently Undercharging
3/ Leaving in an under-charged condition
4/ Too high a S.G. of Electrolyte

(c) 1/ Voltage falls rapidly on use.
2/Cell gets hot on charge
3/ S.G. fails to rise on charge.

(d) 1/ Long charge at 1/3 normal rate with weak Electrolyte replace with correct S.G. afterwards.

(a) [underlined] HYDRATION [/underlined] The formation of hard white lead hydrate on the plate

(b) Leaving plates exposed to the air

(c) As for sulphation.

(d) As for sulphation

(a) [underlined] BUCKLING [/underlined] The bending or swelling of the plates

(b) Charging & Dis-charging at to [sic] high a rate

(c) may cause internal short circuit.

(d) NO. CURE

(a) [underlined] SHEDDING [/underlined] Dropping out of active material

(b) Old age, greatly increased by over-charging & vibration

(c) Lack of capacity & voltage falls rapidly on discharge.

(d) NO CURE

When charging Accs. allow 1/2 inch between each acc & 2 inches between each bank so that spilled electrolyte cannot cause short circuit between one or more of the accs.

[page break]

[underlined] Quarterly Capacity Test. [/underlined] - Every quarter accs should be tested on capacity test board. Set voltage selector switch to correct position to cover voltage of acc. Take meter readings. Set rheostat to give correct readings in ammeter for dis-charge at 10 hr rate. If acc becomes discharged in 3/5 hrs or less of its rated capacity it cannot be used in aircraft. It should then be painted with a yellow band or spot to show that it is u/s for use in aircraft.
[underlined] General Points to Remember. [/underlined]
Always keep accs. clean.
Keep a thin coating of mineral jelly on the lugs.
Always give correct first charge.
Use distilled water for topping up unless acid has been spilt.
Recharge acc. at the correct rate.
[underlined] Spilt Acid. [/underlined] - Saw dust to soak up. Bi-carbonate of soda to neutralise it.
[underlined] Mixing Acid. [/underlined] - Always add acid to water.
[underlined] Simple Charging Board. [/underlined]

[diagram]

[underlined] Main Essentials. [/underlined]

1./ Source of E.M.F.
2./ Double Pal quick acting switch
3. Fuses to safeguard supply & accs on charge
4/. Ammeter
5./ Rheostat
6/ Cut Out.
When connecting accs. to charging board keep the positive lead short & the negative lead long.

[page break]

[underlined] MAGNETISM. [/underlined]
[underlined] RETENTIVITY [/underlined] (Retaining Power) - Steel has high retenivity [sic]. Iron has low retentivity.
The magnetic lines of force flows out of the N. Pole into the S. Pole. Lines of force never cross each other.
Like poles repel. Unlike Poles attract. Able to exert power over a distance. The ease of passing magnetic lines of force is called [underlined] Permeability. [/underlined] [underlined] Reluctance [/underlined] is the opposition to the flow of lines of magnetic Force.
[underlined] Electro Magnets. [/underlined] All rules in magnetism refer to
[underlined] Electric current flow. [/underlined]

[circled+] Current Flowing Into Conductor
[circled .] Current Flowing Out of Conductor

[underlined] Maxwell's [deleted] Fleming's [/deleted] Corkscrew Rule. [/underlined]
[symbol] Corkscrew into cork current flowing clockwise
[symbol] Corkscrew out of cork current flowing anti-clockwise.

[symbol] [symbol]

[underlined] Electro Magnet. [/underlined]

[diagrams]

[page break]

Iron Cores increase magnetic Solenoid up to 500 Times
The magnetic field only exists round Solenoid while current is switched on

[underlined] Production of E.M.F. (mechanical). [/underlined]
[underlined] Faraday's Rule. [/underlined] When a conductor cuts a magnetic field or vice versa an E.M.F. is induced into that conductor. This E.M.F. is proportional to the rate of cutting. The size of the E.M.F depends on 1/ flux density 2/ length of conductor 3/ Velocity. The E.M.F. depends on the number of lines of force cut per second.
[underlined] Flemings right hand rule. [/underlined]The forefinger indicates the direction of the magnetic lines of force. The thumb indicates the direction of cutting the lines of force. The 2nd finger will then indicate the direction of induced E.M.F. All fingers must be held at right angles to each other.
[underlined] Transformers. [/underlined]
A charging current in primary coil causes a moving magnetic field. This cuts the secondary coil & induces an [deleted] d [/deleted] alternating E.M.F pulsating D.C. or A.C. only can be used in the primary.
The E.M.F. induced in secondary is always alternating.
W = V x I W = V x V/R W = I x R x I = I2R
The unit of power is the Watt

[diagrams]

[page break]

[underlined] The Simple Generator. [/underlined]

[diagrams] GRAPH SHOWING SIGN WAVE AC CURRENT

The simple generator consists of a loop of wire revolving between the poles of a permenant [sic] magnet. The two ends of the loop are connected to slip rings on the spindle, carbon brushes make contact with these rings and pick up the induced E.M.F. for output. The output from the generator is alternating. [symbol]
In order to change the output into D.C. we use a commutator. This is a form of automatic switch which reverses the connection between the ends of our loop & the brushes. The commutator consists of a cylinder made of ebonite or some insulating material which is keyed to the shaft. This carries 2 half rings of copper or brass which are insulated from each other. The carbon brushes make contact with these sedgments alternately. This provides an automatic switch which operates when direction of current changes.
The output now [underlined] becomes pulsating [/underlined] D.C. (direct current).
If we increase the number of loops in a genera [missing word/s] the output becomes smoother & the E.M.F. in {missing word/s]

[page break]

For each loop 2 sedgments are needed on the commutator. The brushes in a generator are usually made of carbon. The armature usually has an iron core which is lamenated [sic] to prevent eddy currents.
These lamenations [sic] are usually insulated from each other to prevent rusting.
[symbol] Field Magnet, Armature, Armature Windings, Commutator, Carbon Brushes (Essentials of a Generator.)
The pole pieces are usually shaped to reduce air gap between armeture [sic] and full magnet.

[underlined] THE MOTOR PRINCIPLES. [/underlined]

[diagrams]

[underlined] Position 1. [/underlined] Magnetic lines of force would try to straighten & loop will be forced round in clockwise direction.
[underlined]Position 2. [/underlined] Weight carries loop over top dead centre, but m. l. of force will force it round in an anti-clockwise, direction until it reaches position 3. By reversing current through loop by means of a comminator the direction of the magnetic lines of force round conductor will be reversed & the loop will once more be forced round in a clockwise direction as in position 4. This twisting effect is called the torque.

[page break]

[underlined] Flemings Left Hand Rule. [/underlined] is that the forefinger placed in the direction of the lines of force, the second finger indicates the direction of the applied E.M.F. the thumb indicates the direction of rotation.
The need for starting device on electric motor.
The Lenzs Law says if a conductor cutting a magnetic field has an E.M.F induced into it, that E.M.F will be in opposition to the applied force.
This induced E.M.F. is called back E.M.F. & is only present when the armature is turning. It builds up as speed increases. This back E.M.F. is in opposition to the applied E.M.F. [symbol] it causes windings to have an apparently increased resistance. At the moment of starting however there is no back E.M.F. & as the resistance of the windings is low there will be an heavy surge of current which would damage armature.
[underlined] Type 'E' Motor Generator. [/underlined]

[diagrams]

[page break]

[underlined] Description [/underlined] of Shunt wave motor & seperately [sic] excited generator.
[underlined] Input. [/underlined]
12 v
14 v
12.5 amps
166 watts approx

[underlined] Output [/underlined]
1000 v
1200 v
65 milliamps on load (more 72 ma)
86.4 watts maximum
Speed 5800 revelutions [sic] per min Efficiency 50% [underlined] Losses 1. [/underlined] 1 copper loss due to resistance of copper 2/ Iron Loss due to eddy currents 3/. Friction losses due to air resistance & bearing friction. Motor brushes made of copper carbon to give low resistance there-by avoiding big volts drop with heavy current necessary to run motor.
Motor Commutator consists of small number of large sedgements 2 to each group connected to low resistance motor windings.
Generator Brushes made of carbon
Generator Commutator consists of a large number of small sedgments 2 for each loop.
[underlined] Spark Suppressors. [/underlined] 4.01 mfd condensers by-pass high frequency to earth thus reducing the effects of sparking which would otherwise take place in radio equipment.
[underlined] Smoothing. [/underlined] One .5 mfd condenser connected across output helps to smooth out commutator ripple.
[underlined] Lubrication. [/underlined] 5 Drops of duckham's anti-freeze oil every 30 to 40 running hours.
is

[page break]

Type "A" Starter Operation.
When remote switch is closed, solenoid "A" closes soft iron switches thus completing circuit through field windings & through .24 [symbol] resistance to armature.
This resistance limits current at moment of starting.
Solenoid "B" is in parelell [sic] with armature so that volts drop across the two will be the same. As the BE.M.F. builds up in armature volts drop will increase when effective resistance of armature is twice that of starter resistance volts drop across armature & Solenoid "B" will be approx 8 volts. When this figure is reached Solenoid "B" will operate & close soft iron switch thus shorting out starting resistance.
Care of [deleted word] Commutator
(a) [underlined] CAUSE [/underlined] (b) [underlined] EFFECTS [/underlined] (c) [underlined] CURE [/underlined]

(a) Dirt (b) Loss of input to transmitter
Flickering input to transmitter
Bad note reported & interference to radio receiver. (c) Clean commutator with petrol damp rag. In extreme cases use fine glass paper (not emery paper as this is a conductor)

(a) Overload [deleted] Dirt [/deleted] (b) Loss of input to transmitter
Flickering input to transmitter
Bad note reported & interference to radio receiver.
motor turns slowly & gets hot. (c) never exceed 72 output

(a) Badly worn or broken brushes. (b) Loss of input to transmitter
Flickering input to transmitter
Bad note reported & interference to radio receiver.
motor turns slowly & gets hot. (c) Replace and [missing word/s] in Brush [missing word/s]

(a) Badly scarred or grooved commutator. (b) Loss of input to transmitter
Flickering input to transmitter
Bad note reported & interference to radio receiver.
motor turns slowly & gets hot. (c) Hand to [missing word/s] skin & [missing word/s]

(a) Proud Mica. (b) as above (c) as [missing word/s]

[page break]

(a) Weak Springs (b) as above (c) Hand to mechanic for spring tension to be increased.

[underlined] Elementary Alternating Current. [/underlined]

[diagram]

A cycle is one complete wave form. The frequency is the number of complete cycles per sec.
Current in which the electron flow moves first in one direction & then in the other called A.C.
The amplitude is the maximum current or E.M.F from zero in either direction.
[underlined] Speed of Radio Waves [/underlined] = Wavelength
Frequency
[underlined] Inductors. [/underlined] A conductor wound in the form a solenoid is called an inductance. When a current change takes place in such a coil the magnetic lines of force will build out round each individual turn, & will cut its neighbouring turn, thus causing E.M.F. to be induced into it. In accordance with Lenz's Law this E.M.F. will be in opposition to the applied force.
This induced E.M.F. tends to stop the current from building up so that a gradual rise takes place. On switching off, the induced E.M.F will be in such a direction as to try & keep the current from slowing.
is

[page break]

[underlined] Inductance [/underlined]- is the property of a coil of wire to oppose a change of the current flowing through it
[underlined] Induction [/underlined] - is the action of inducing an E.M.F. into a conductor.
[underlined] Self Induction [/underlined] is the action of inducing an EMF. in a conductor by reason of the current change in that conductor.
[underlined] Mutual Induction. [/underlined] The action of inducing an EMF. in one conductor by reason of a change of current in the second conductor.
[underlined] Unit of Inductance. [/underlined] - If a current is charging at the rate of 1 amp per sec & the voltage induced in the coil is 1 volt then the inductance is said to be 1 henry.
[underlined] Inductive Reactance [/underlined] is the measurement in OHMS of the opposition of a coil of wire to A.C. or changing current. It is directly proportional to the frequency & to the inductance.

[underlined] Condensors [/underlined]
If we charge 2 plates or bodies, one positive & the other negative a state of strain would exist between those plates if held a small distance apart. The lines of force which exist between these plates is called an electro-static field. The space or material between the plates is called the Dielectric. The capacity [missing word/s] a condensor depends on the size of the plates [missing word/s] the goodness of the Dielectric. The better the [missing word/s]

[page break]

Dielectric the closer the plates can be & they will therefore hold a greater charge. A condenser offers no path for D.C.

[diagram]

Condensors in Parallel capacities add to-gether C = c1+c2+c3
Condensors in Series 1/c=1/c1+1/c2+1/c3
The unit of capacity is the Farad
[diagram] In Series
In parallell [diagram]
m.f.d = micro-farad
A Condensor connected to a source of A.C. charges up first in one way & then the other giving the appearance of passing current. A condensor [symbol] offers no path for DC. but appears to offer an easy path to A.C.
[underlined] Variable Condensors [/underlined] The capacity of a condensor is usually varied by altering the overlap between the plates. [underlined] Capacitive Reactance [/underlined] is the opposition of a condensor to A.C. It is inversely proportional to frequency & capacity. It is measured in Ohms. If you increase frequency or capacity you decrease reactance.

[underlined] Closed Oscillatory Circuits. [/underlined]

[diagrams]

[underlined] Damped Oscillations. [/underlined]

[page break]

Inductance indicated by L
Capacity indicated by C.
The bigger LC [unreadable] is the slower she operates.
[underlined] Residence [/underlined] - If the reactance of the coil = the reactance of the condensor the circuit is said to be tuned to its resident frequency, or to the frequency at which it will oscillate most readily.

[diagram] Parallel - Rejector Circuit

[diagram] Series - Acceptor Circuit.

[underlined] Tuned Circuits [/underlined] If we arrange a circuit with inductance and capacity sizes carefully selected so that the circuit oscillates at its resident frequency it is called a tuned circuit. In the case of a parallel tuned circuit (rejector) we get minimum current flowing [deleted] with [/deleted] when tuned to residence.
One of the main uses for rejector tuned circuit is in the anode circuit of a valve. With a series tuned (acceptor) circuit maximum current flows when tuned to residence
Main use of series circuit is an [unreadable] aerial.
[underlined] Open Oscillitary [sic] Circuits [/underlined] - If we open out the [missing word/s] of our condensor in the form of aerial & [missing word/s] electric field or strain is spread over [missing word/s]

[page break]

large area. These lines of force alternate first in one direction & then in the other. The resultant radiation is a combination of electric lines of force & Electric Magnetic Waves. This movement in the ether is transmitted or passed on from particle to particle & gives us wireless waves which travel at 186,000 miles per sec or 3000,000,000 metres. At frequencies below approx 100,000 cycles radiation is not too satisfactory.
Audio Frequency is between (AF) 15 c/s to 15,000
Radio Frequency is between (RF). 15,000 c/s upwards.

[underlined] Low Frequency [/underlined] [symbol] Big Capacity - Long Aerial
[underlined] Long Wavelength [/underlined]
[underlined] High Frequency [/underlined] [symbol] Low Capacity - Short Aerial
[underlined] Short Wave [/underlined]

[underlined] The Thermionic Valve [/underlined]
[underlined] Flemings Two Electrode Valve. [/underlined]

[diagram]

[underlined] DIODE VALVE [/underlined]

[diagram]

[underlined] DIODE [deleted] OXID [/deleted] VALVE [/underlined] has 2 Electrodes c. filament & a. plate When we apply A.C. Anode goes first positive & then [missing letters] egative. Current only flows when anode is positive. [missing word/s] it rectifies A.C. to pulsating D.C. & is called a [missing letters] her or detector valve.

[page break]

[underlined] GRID [/underlined]

[diagram]

[underlined] VALVE BASE [/underlined]

materials used for Filaments - Tungsten treated with coating of oxide of either Barium, Strontium or Calcium gives a good emission at low temperatures. Efficiency is increased sometimes as much as 500 times. If positive potential of anode is increased current flowing will increase. If potential is decreased, current will decrease.
[underlined] Triode Valve [/underlined] (3 Electrodes) The triode valve has an extra electrode called "control grid" which is in the form of a wire mesh between the filament & anode. By making grid negative enough all current could be prevented from flowing through the valve. Being closer to the filament control grid will have a much greater effect on the current than the anode. An increase of approx 30 volts positive on the anode gives roughly the same current charge as an increase of 1 1/2 volts positive on the grid. This potential which we put on the grid is called grid bias.
[underlined] Three Uses of a Triode Valve [/underlined] 1./ Rectifier 2./ Amplifier 3./ Oscillator
[underlined] Rectifier. [/underlined] The grid is biased negatively to cut off point so that anode current will not flow. Positive 1/2 cycle reduces negative bias & current flows. During negative 1/2 cycle grid becomes more negative & anode current will not flow. In fact A.C. is changed to pulsating DC.
[underlined] Amplifier. [/underlined] A small change in grid voltage gives a big change in anode current. If we place a resista [missing letters] in the anode circuit, this changing current wil [missing letter/s]

[page break]

cause a changing volts drop across the resistance at the same frequency as the changes in the grid circuit. A valve by itself is not an amplifier. To use as such an anode load is essential.

Radio Frequency Continuous Wave or Carrier Wave [diagram] Audio Freq [diagram]

[deleted] Radio Freq With [/deleted] [diagram] Radio Freq with Amplitudes Varying at Audio Freq modulated Carrier Wave (MCW).

[underlined] Telephone Earpiece. [/underlined]

[diagram]

[diagram]

[diagram]

[underlined] 1 Valve (Triode) Set [/underlined]

[diagram]

[underlined] ANODE BEND DETECTION [/underlined]

[page break]

[underlined] Reaction [/underlined] is the feed back of energy from the anode to the grid circuit of valve. Its uses - it will boost signal and give greater selectivity. Reaction can be varied by altering the capacity of the condensor, or by varying the anode voltage. The more current passing through the valve the greater the amount of energy that can be fed back.
[underlined] LEAKY GRID DETECTION [/underlined]

[diagram]

[underlined] The Heterodyning Principle [/underlined]

[diagrams]

Morse transmissions are usually in the form of a continuous wave which is sent out in short & long bursts by means of a morse key. The signal like this will have to be detected, but even then it will be pulsating at such a frequency that it wi [missing letter/s] be above audability [sic]. In order to make the [missing word/s] audiable [sic] we generate a local oscillation [missing word/s] receiver the frequency of which differs by an audio fre [missing letters]

[page break]

This produces a difference on beat frequency which can be heard in the phones.
[underlined] Aetodyning [/underlined] is really the same as reaction, only in this case we feed back more energy causing grid circuit to oscillate. ie/. it becomes a valve maintained oscillator. This oscillator mixes in the valve with incoming signal & provides a beat note.
In [underlined] leaky grid detection [/underlined] the condensor and 1 meg [symbol] resistance which is connected to the grid act in the same way as the grid bias battery does in anode bend detection. During the + 1/2 cycle of the incoming signal a negative charge builds up on the plate of the condensor which is connected to the grid. During the - 1/2 cycle the condensor will try to discharge and electrons will flow on to the grid in an effort to get to the filament. As this is impossible in a valve the only means of escape is through the 1 meg [symbol] resistance, and as this is a very high resistance the condensor cannot completely discharge. During this - 1/2 cycle the electrons on the grid will be sufficient to prevent anode current flowing. By the next + 1/2 cycle sufficient electrons will have leaked away through the 1 meg [symbol] resistance to allow anode current to flow. In this way 1 half of our wireless wave is cut off.
Leaky Grid for weak signals.
Anode Bend for strong signals.

[page break]

[underlined] A.F. Amplification COUPLING [/underlined]

[diagram]

[underlined] RESISTANCE CAPACITY COUPLING [/underlined]

[diagram]

[underlined] CHOKE CAPACITY COUPLING [/underlined]

[diagram]

[underlined] TRANSFORMER COUPLING [/underlined]

[page break]

[underlined] Disadvantages [/underlined]
[underlined] Resistance Capacity Coupling [/underlined
The disadvantages of this type of coupling is that some of the voltage applied to the anode will be dropped across resistance forming anode load. This is not too important in detector stages but it can cause a considerable loss in power if used in output stages.
[underlined] Choke Capacity Coupling [/underlined] has the disadvantage that the reactance of the choke would differ at different frequencies & that DC. passing through the windings tends to cause residual magnetism in the iron core.
[underlined] Transformer Coupling [/underlined] has the same disadvantages as C.C.C. but is useful in small sets were [sic] amplification is more important than faithful reproduction.
[underlined] A Grid Bias Battery [/underlined] is necessary to bias valve to straight portion of the characteristic curve otherwise rectification or distortion of the signal would take place.

[underlined] R.F. AMPLIFICATION [/underlined]

[page break]

[underlined] Screen Grid Valve [/underlined]

[diagram]

[diagram]

TOP CAP - [underlined] ANODE [/underlined]

[underlined] Interelectrode Capacity [/underlined] is the name given to the condensor effect which exists between the electrodes of a valve. This is called [deleted letter] C.A.G. C.A.F. C.G.F.
C.A.G. is the most important but is only really serious when we are dealing with radio frequencies. (The higher the frequency the lower the reactance). Through this C.A.G. energy will be fed back from the anode to the grid circuit of our valve in a similar way to reaction the only difference being that it is uncontrollable.

[page break]

[underlined] TRF RECEIVER. [/underlined]

[diagram]

[underlined] The Necessary Stages of a Receiver [/underlined]

[diagram]

[underlined] The Detector Stage [/underlined] is essential in order to sort AF from the RF which can be used to operate phones or further stages (Diode or Triode)
[underlined] R.F. Amplifying Stage. [/underlined] If signals are too weak to be detected properly we can amplify them before passing to our detector stage. If we use more than two stages of RF we run the risk of distortion in our receiver. The extra controls would make the set difficult to tune (screen grid)
[underlined] A.F. Amplifying Stage [/underlined] If after leaving the Detector stage our signal is still weak we can add a further stage of amplification. It is adviseable [sic] to use only two stages of AF otherwise we should [missing word/s] load our output valve.

[page break]

[underlined] Power Output Stage [/underlined] For loudspeaker operation [missing word/s] of power is needed so if it is necessary we c [missing letters] add a power output stage & as before use a triod [missing letter/s]

[underlined] THE R 1082 TRF RECEIVER [/underlined]

[diagram]

The R1082 is a lightweight general purpose receiver capable of receiving all types of signals. (M.C.W. RT & CW
For aircraft or ground use with the T 1083 transmitt [missing letter/s]
[underlined] Frequency Range [/underlined] is 111 [deleted 100 [/deleted] K/cs 15,000 K/cs 14 pairs [missing word/s] plug in coils, lettered from A to P. The letter I is [missing word/s] The green coil anode, red coil the aerial.
[underlined] Power Supplies. [/underlined] [underlined] H.T. [/underlined] 120 volts HT battery [underlined] LT [/underlined] 2v14 [missing word/s] 2v20 acc.
[underlined] Power Consumption [/underlined] H.T. 15 milliamps approx. LT with dial light & limiter valve 1.25 amps L.T. with limiter valve only 1.05 amps. L.T. without limiter valve or ch [missing letter/s] light .65 amps
[underlined] Aerials [/underlined] Long trailing 200 to 250 feet stainless steel wire [missing word/s]
Short Fixed Aerial for H.Frequency
Tight coupling gives maximum sensitivity or v [missing letters]
Loose coupling gives maximum selectivity
[underlined] Limiter Valve [/underlined] VU 33 is a diode & it acts as [missing word/s] valve when transmitted, [missing letters] nts too stro [missing letters]

[page break]

a signal from transmitter being picked up by receiver on 'listening through' conditions.
[underlined] Control. [/underlined] The first control is the volume control which is a Potentiometer which varies the positive voltage on [deleted word] the screen grid of our R.F. Amp valve.
[underlined] Reaction Control. [/underlined] The feed back of RF from anode to grid of detector valve is controlled by a potentiometer which varies the anode voltage of detector valve. This varies the amount of current through the valve & therefore varies at the same time the amount of energy fed back.
[underlined] Automatic Bias [/underlined] is applied to 1st AF valve negative 1 1/2 volts
2nd AF negative 1 1/2 volts and output valve - negative 3 volts. This bias is obtained by placing resistances between H.T. negative & earth. The volts drop across these resistances is used as a grid bias.
[underlined] Circuit Details [/underlined] R.F. Stage is capacity coupled to detector. The detector is RCC. to 1st AF. The 1st AF. is RCC to 2nd A.F. The 2nd AF. is C.C.C. to output.
[underlined] Tuning Condensors. [/underlined] Tuning on both anode & aerial circuits is carried out by means of variable condensors. If condensors are moved from 0 [symbol] towards 180 [symbol] the capacity will be increased & the frequency decreased.
[underlined] Tuning Notes [/underlined] 1./ Check External Connections H.T. L.T. Aerial Phones & Earth
[missing number] Plug in Correct Coils.
[missing number] Switch on Receiver and set volume control to [missing letters] ximum.

[page break]

4/ For CW reaction must be just past [missing word/s] point. This can be checked by touching [missing word/s] finger. If a loud click is heard in the L/S [missing word] set is oscillating. For MCW ICW & RT it must be just off oscillating.
5/ Search for signal with both tuning condensors keeping them in step.
6./ Adjust reaction & aerial tuning control for maximum signal strength
7 Correct anode tuning as necessary & adjust volume control & aerial coupling as required

[underlined] C W TRANSMITTER. [/underlined]

[diagram]

[underlined] MEISNER OPEN TRANSMITTER [/underlined]

[underlined] Disadvantages of a Single Valve Transmitter [/underlined] are unstable frequency & low power transmissions.
[underlined] Causes of Instability in a Single Valve Transmitter [/underlined]
1./ Movement of Aerial
2./ Mechanical Instability
3/. Instability due to [deleted word] outside electrical [missing word/s] cured by screening.
4./ Heating due to overheating valve. Cured by w [missing letters] at low power or providing [missing word] ventilation

[page break]

[underlined] MO - PA TRANSMITTER [/underlined]

[diagram]

[underlined] Master Oscillator Stage. [/underlined] The main requirements of the MO. Stage is frequency stability and the ability to [missing word] set up to any desired frequency. To maintain [missing letters] tability M.O. Stage is screened, run at low power, made [missing letters] chanically rigid & isolated from aerial by PA
[underlined] Power Amplifier Stage. [/underlined] Amplifies the signal generated [missing word] the MO. giving greater power & radiation. The PA also isolates the MO. from the aerial.

[underlined] CARBON MIKE [/underlined]

[diagrams]

[underlined] TELEPHONE EARPHONE [/underlined]
The permanent magnet prevents frequency doubling

[page break]

[diagram]

[underlined] THE 1083 [/underlined]
The PA suffers from the usual feed-back effect at Radio Frequencies & this valve, if the triode is prevented from oscillating by feeding back [underlined] reversary [/underlined] action until the effect is cancelled out. This is called [underlined] Neutralising. [/underlined] Alternately the more modern method of employing screen grid valves or tetrodes for PA can be used.
[underlined] MODULATION. [/underlined]
[underlined] Grid Modulation. [/underlined] If we apply an A.F. E.M.F. between grid & filament of a PA Stage we shall vary the R.F. current from the M.O. at A.F. The PA tuned [deleted word] circuit will therefore contain R.F. oscillations varying at AF
[underlined] Anode Choke. [/underlined] If we apply an A.F. E.M.F. [deleted words] to a modulation valve, we will cause a varying P.D. across the choke, now as this carries the DC input to the PA, the tuned circuit of the PA. will be varied accordingly.
The P.A. is always modulated, never the M.O. the [missing word] controls the frequency.

[page break]

[underlined] Anode Tap & Aerial Tap. [/underlined] [deleted] The [/deleted]
[underlined] Anode Tap. [/underlined] It can be shown that the maximum [underlined] power [/underlined] output from the PA is greatest when the internal resistance of the valve is equal to the external load into which it feeds. This is accomplished by tapping down the PA coil.
[underlined] Aerial Tap [/underlined] is to control the natural frequency of the aerial tuned circuit. When this matches the PA tuned circuit the maximum power output derived above is radiated freely from the aerial without loss

[diagram]

[page break]

[underlined] THE T1083 TRANSMITTER. [/underlined]

[diagram]

The T.1083 is a lightweight aircraft transmitter capable of radiating C.W. I.C.W. & RT. Normally accompanied by the R 1082 Receiver. The Frequency Range is actually from 136K/cs to 500 K/cs and from 3 to 15 m/cs
[underlined] Range D [/underlined] covering 136 to 500 K/cs is a colpitts oscillator, no neutralising is necessary. It is a tapped inductance with variometer fine tuning. The M.O. is capacity coupled to the PA.
[underlined] CI Range [/underlined] Covers from 1500 to 3000 K/cs. Hartley Oscillator. Neutralising is necessary, but for normal tuning is sufficient to leave neutralising condensor set at 45 [symbol]. Continuously variable inductance. The M.O. is inductively coupled to the P.A. Amplifier Grid Bias Switch. This switch controls the negative bias on the grid of the PA valve. In the tuned position 350 volts negative. This prevents anode current flowing through the P.A. valve & stops transmission while setting up MO.

[diagram]

AMP GRID B

When PA Stage is tuned to MO. input [missing word/s] shows minimum reading.

[page break]

[underlined] Tuning on CI Range [/underlined] Artificial aerial to 110 m mfd check that correct terminals on artificial aerial are selected. Switch to send. Generator Switch on (make sure filaments light up). Set M.O. control to frequency desired. Neutralising meter to transmit. The A.G.B switch to RTI or CWI neutralising condensor to 45 [symbol] Tune the PA for maximum aerial and for minimum input current
[underlined] Tuning on D Range. [/underlined] Set artificial aerial to correct setting. Switch to send & if filaments light up switch generator on. Set M.O. control to frequency desired. Neutralising meter switch to transmit. AGB Switch to RT I or CW I. Set neutralising condensor to 0 [symbol]. Tune PA for minimum input & maximum aerial current.
[underlined] Wavemeters. [/underlined]
[underlined] The Neon Wavemeter N63. [/underlined]

[diagram]

When this wavemeter is placed near transmitter & tuned to resonance with it maximum energy will be induced into its tuned circuit. Condensor will charge up & the EMF crosses plates is applied to a neon lamp. If wavemeter is tuned accurately this EMF is sufficient to strike the gas. Its advantages :- no Power supplies needed, is compact and has simple tuning. Disadvantages :- not very accurate and has limited range, 150 to 600 K/cs Range.

[page break]

[underlined] The W 1117 Wavemeter. [/underlined]
Is a two valve set consisting of RF Amp Stage, which is a tetrode VW 48 & a detector stage using a triode VW 36. Its Anode Bend Detection. [underlined] Power Supplies [/underlined] :- 120v HT full voltage on RF valve & 60 volts on the detector. Low Tension is a 2v7 acc. Grid Bias. 4 1/2 volts battery.
[underlined] Frequency Range [/underlined] 1, 2, 3, & 4 M.F. 125 K/cs to 2 m/cs. Range 5, 6, & 7 H.F. 2 m/cs to 20 m/cs. A callibration [sic] chart is used to set up dials. The left hand control controls the HF ranges. & is a continuously variable [deleted] resistance [/deleted] inductance. The right hand control is for M.F. and is a variable condensor. A micrometer is used instead of phones & forms anode load through detector valve. Maximum reading gives maximum signal. [underlined] Disadvantages are [/underlined] :- Supplies needed, very bulky & needs careful adjustment.

[underlined] The G.P.I. R 1082/ T 1083. [/underlined]
[underlined] General Purpose Transmitter and receiver. [/underlined]
When using the GPI for 2 wave communication, the receiver & transmitter at each end must be tuned to the same frequency. For listening through [deleted] at [/deleted] on the same frequency following points must be noted: 1/ Listening through condensor must be fitted.
2/. Limiter valve must also be fitted to prevent damage to receiver. 3/ MO. and PA must be keyed.
4/. Suppressor condensors must be fitted to M Generator
[deleted] 5/. [/deleted] [underlined] Tuning Receiver to Transmitter. [/underlined]
1/. Always switch on receiver first.

[page break]

2/. Tune transmitter to desired frequency in normal way.
3/. Plug headphones & coils in receiver.
4/. Set volume control at minimum, reaction at maximum
5/. Tune receiver until note is heard, then adjust dead space & offset tuning until required beat note is heard.
[underlined] Listening Through Condensor. [/underlined]
When transmitter & receiver are in use together signal should be tuned in on free receiver, that is aerial should be disconnected from L.T. condensor & connected straight to receiver lead.

[diagrams]

Pentode Valve

[underlined] Crystal Oscillators. [/underlined]
The AT cut crystal is used in wireless owing to the fact that it is not affected by change in temperature. These crystals are very much the size of a halfpenny, & are placed between [deleted] between [/deleted] two brass plates which are dead flat. The frequency of such a crystal is accurate to 2 parts in a million. Crystals are used to take the place of tuned circuits [missing letters] ere stable frequency is essential. Cannot be used

[page break]

where heavy oscillating currents, or DC. is to be passed OK for use in the M.O. stage of M.O. P.A. transmitter. M.O. which is crystal controlled is called a crystal oscillator.

[diagram]

[underlined] PEARCE OSCILLATOR. [/underlined]

[underlined] CRYSTAL MONITOR [/underlined] designed for use in aircraft to set up & check frequency on transmitters & receivers. The monitor is crystal controlled & up to seven spot frequencies can be rapidly selected by a seven position switch. Six of the crystals are inside set & the 7th is plugged into the front of panel. It uses 3 VT 50 triodes 1 as detector - oscillator & the remaining 2 as A.F. amplifier. [underlined] Range. [/underlined] - normal range is reckoned to be 1 m/cs to 7.5 m/cs. Giving accurate check up to 15 m/cs on second harmonica.
[underlined] Power Supplies [/underlined] 120 v HT battery 2v14 or 2v20 LT 4.5 grid bias battery. When used with R 1082 by moving a small disc inside, the same power supplies can be used as for receiving.
[underlined] Setting up a Transmitter. [/underlined] Set up transmitter as previous instructions to approx frequency. Set monitor selector switch to appropriate crystal and plug in ph [missing letters]

[page break]

Tune transmitter M.O. until beat not [sic] is heard then tune to dead space. Retune P.A. [deleted] setting up [/deleted]
[underlined] Setting up Receiver [/underlined] Select appropriate crystal & switch on monitor, plug phones in receiver. Tune receivers for beat note & then adjust to dead space. With R1082 reaction to oscillation point, volume to half strength.
[underlined] Advantages [/underlined]:- very accurate and compact. Can be used to set up transmitter & receiver.
[underlined] Disadvantages [/underlined] :- Supplies needed.

[underlined] The Superhet Principle. [/underlined]

[diagram]

In order to increase the selectivity of a set we have to increase the number of tuned circuits. The more tuned circuits the more selective the set becomes. If these circuits are added in the form of R.F. amplifiers, the number of tuning controls will make the set difficult to tuning in.
In a superhet we have a local oscillator which provides a signal which we mix with the incoming [missing letter] ignal to provide a beat frequency. No matter

[page break]

what the frequency of the incoming signal. The local oscillator can be tuned to give us the same beat frequency output from the mixer valve. The beat frequency is a low radio frequency & is called intermediate or supersonic frequency. It varies between 100 K/cs and 500 K/cs. [underlined] The Advantages of a Superhet [/underlined] :- more selectivity & sensitivity. Set remains stable. Screen grid valves will give us more amplification when amplifying a low radio frequency.
[underlined] Disadvantages [/underlined] :- Second channel interference. Can be cured by having a selective R.F. amplifying stage.

[underlined] TR9F Transmitter - Receiver [/underlined] [underlined] Block Schematic. [/underlined]

[diagrams]

[page break]

[underlined] TR9F [/underlined]
[underlined] TR9F. Description. [/underlined] A lightweight low power crystal controlled radio telephony set for use in aircraft.
[underlined] Range. [/underlined] 35 to 50 miles air to ground 5 miles air to air
[underlined] Frequency Range [/underlined] 4.3 m/cs to 6.6 m/cs
[underlined] Power Supplies [/underlined] Tx and Rx 1 120 v HT battery to be charged when voltage falls to 100 volts & 1 2v20 or 2 v 14 L.T. (The HT & grid bias for Tx stored in tray at back of the Tx)
Grid Bias. Tx 15v battery tapped at 10.5v. for mod valve. Rx 4 1/2v battery tapped at 4.5 for output valve, and 1.5 for each of the R.F. amps
[underlined] Power Consumption [/underlined] Tx HT. 26 to 28 milliamps Rx HT 13 to 15 m amp LT Tx x Rx 1.25 amps on normal 1.6 amps on special (.35 [deleted] of [/deleted] amps used by relay). [underlined] Aerial. [/underlined] Short stub mast type.
[underlined] Transmitter Section [/underlined] Crystal oscillator accurate to 2 c/s in a million. Can be set up to 2 spot frequencies. [underlined] normal & special. [/underlined] [deleted] It appears [/deleted] Pearce Oscillatory Circuit
P.A. [underlined] Normal Tuning [/underlined]continuously [deleted] in [/deleted] variable inductance
[underlined] Special Tuning [/underlined] Course tuning is a tapped inductance
Fine Tuning by small variable condensor PA coil is also used as aerial coil in receiver, [symbol] it is always necessary to tune Tx before Rx
[underlined] Valves [/underlined] Crystal Oscillator VT 50 triode PA & modulator VT 51 Pentodes or beam tetrode with pentode characteristics.
[underlined] Coupling [/underlined] between MO & PA is Capacity Coupling.
[underlined] Modulation [/underlined] Speach [sic] frequencies from microphone are amplified in the A 1134 & further amplified by modulator valve. From there they are passed [missing word/s] the PA valve by anode choke modulation system.

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[underlined] Send Receive Switch [/underlined] [underlined] Send Position [/underlined] LT to Tx & Rx HT to Tx only. PA coil to transmitter [underlined] Off position [/underlined] All supplies disconnected [underlined] Receive position. [/underlined] LT to Tx & Rx HT to Rx only. P.A. coil to Rx.
[underlined] Meters. [/underlined] [underlined] Input. [/underlined] Moving coil type 0 to 30 milliamps scale
[underlined] Aerial Current [/underlined] Thermocoupled moving coil 0 to 5 amps scale
[underlined] Shorting Plug & relay. [/underlined] Switches over from normal to special crystal & normal to special tuning.
[underlined] Microphone. [/underlined] Electro Magnetic Type. Sensitive 500 to 1600 c/s. Side tone is provided to enable to operator to hear his own voice in the phones.
[underlined] Receiver Section. [/underlined] P.A. coil is grid circuit to 1st RF valve. Anode tuning on both RF Stages by two variable condensors.
[underlined] Pilot's Fine Tune. [/underlined] By 2 gang trimming condensors 1 in parralell [sic] with each main condensor. (180 [symbol] movement covers 3 [symbol] movement on main tuning.
[underlined] Coupling [/underlined] 1st RF to 2nd RF. Anode tune circuit C. Coupling [deleted] & [/deleted] 2nd RF to Detector Anode tune circuit
Detector to 1st AF. 1st AF to 2nd AF. & 2nd AF to Output R.C.C.
Output to A 1134 to C.C.C.
[underlined] Volume Control. [/underlined] A potentiometer which varies the + voltage on the screen grids of both RF valves.
[underlined] Regeneration. [/underlined] The feed back of energy from the anode of 2nd RF valve to grid of the same valve is controlled by means of 10 mmfd condensor.
[underlined] Remote Control [/underlined] is provided over send receive switch (Bowden Cable). Pilots fine tuning (Bowden Cable)
Volume by extension leads on Potentiometer.

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normal Special Frequency by switch.
[underlined] Press to Send switch [/underlined] electrically controlled. Enables rear-gunner to transmit in emergencies. (Connects HT back to Tx.)
[underlined] Tuning Procedure [/underlined] Check all external connections, plug in correct crystals. Tune PA first normal, then special, then readjust normal. Switch on 1134 & test mike for modulation. [underlined] Tune Receiver. [/underlined] Place normal crystal in socket of RT tester & put switch to T.T. Rotate tester tuning dial from low frequency end until change [deleted] of [/deleted] in note is heard. From point where change is heard turn 1 [symbol] further on. This indicates that tester is radiating an AF note on the frequency of the crystal. In order to hear the note, mike should be placed on the [deleted word] heads of 4 screws which are protruding through panel opposite the valves.
Remove mike from R.T. tester. Switch to receive, turn volume control to maximum, pilots fine tuning to 90 [symbol], re-generation to oscillation point, then search for signal on both dials, keeping them in step and starting from low frequency end. *
Replace crystal from RT tester & then slap receiver to ensure that 1/ it will not go into oscillation with vibration.
2/ to test for broken connections (bad or faulty).
3/ to test for microphone valves.
* Turn regeneration [underlined] back 3 turns off [/underlined] oscillation point.

[underlined] Testing Supplies [/underlined] [underlined] H.T. [/underlined] Positive lead of Testmeter to bottom socket of normal crystal and - lead to earth
LT [underlined] Acc [/underlined] Disconnect - lead and put - lead of testmeter on to - terminal of acc. Connect up in series.
[missing word] battery in circuit changed when voltage has dropped to 100v or 110 volt

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[underlined] PENT [deleted] R [/deleted] ODE VALVE. [/underlined]
This is screen grid type of valve with the addition of an extra electrode called suppressor grid. This grid is connected to earth either internally or externally being an earth potential it ensures that all electrons passing through it will go to the anode & not to the screen grid. In other words this valve prevents 'secondary Emmission [sic]!

[diagram]

[underlined] VARI - MU Screen Grid Valve [/underlined]
In a vari-mu valve the control grid is irregularly wound [symbol] when the negative potential is increased on it, anode current will be cut off at the point in the grid where mesh is closest. This type of valve is very useful in sets where volume control is affected by altering control grid potential.

[underlined] Inter Communication Amplifier A1134. [/underlined]
This amplifier is used in aircraft for the inter-comm system & is also used to amplify output of the TR9F Rx & also to amplify the speak frequencies from mike before passing to modulator valve of Tx it acts as a sub-modulator
[underlined] Power Supplies [/underlined] :- 2v20 [deleted v [/deleted] or 2v14 L.T. H.T. 120v Dry Battery Grid B. 6V Dry battery contained inside amplifier.
[underlined] Circuit [/underlined] 1 Triode VR21 AF amp followed by Double Pe [missing letters]

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VR35 acting as quiescent push pull output stage.
[underlined] Selector Switch [/underlined] :- (A) Operator is connected to GPI only rest of crew in intercom. (B). Everyone in intercom & connected to TR9 op also connected to G.P.I Rx (C) position. All crew are in intercomm & connected to GPI & TR9. They can transmit provided transmitter is switched on.

[underlined] Carbon Mike. [/underlined]

[diagram]

The sound waves inpinging [sic] on the diaphram depress & pull out the diaphram, & in doing so compress or release the carbon granules. This causes an altercation in the resistance of the carbon granules as a conductor, resulting in a fluctuating P.D. across the resistance which is varying at AF. This is applied by means of a transformer to the amplifying stage. The diaphram can be of any light flexible material, metal or otherwise. Notice that it is [underlined] essential [/underlined] to have a battery with a carbon mike.
[underlined] The Electro Magnetic Mike [/underlined]

The sound waves inpinging [sic] on the stalloy (steel) diaphram depress & pull out the diaphram, which being placed almost touching the magnet poles, alters the magnet field between the two pole pieces, & in

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doing so induces an EMF. in the coils [deleted] of [/deleted] wound around the magnet. This will therefore be a fluctuating E.M.F. varying at AF. This is applied by means of a transformer to the amplifying stage. No battery required as the EMF is self induced.

[diagram]

The telephone earpiece is of similar construction working on the reverse action.

[underlined] The Mask Mike [/underlined]
Made of chamios [sic] leather on a flexible frame & is airproof. The mike fits at the front of the mask, which when clamped over mouth & nose is in correction position for R/.T. A nozzle protrudes from the side of the mask on to which is fixed the oxygen supply tube.
[underlined] Plugs and Sockets [/underlined]
[underlined] Type 58 or 119 [/underlined]

[diagram]

(see over.)

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[diagram]

[underlined] TYPE 29 [/underlined]
DIAGRAMATIC SKETCH

Used in planes for quick connection & release for both mike & phones.

[underlined] T.R. 1196 [/underlined] designed to replace [underlined] TR9F [/underlined]
Range is set 30miles [deleted words] air to air & 50 to 60 miles air to ground. R/T & [underlined] M.C.W. [/underlined] keying available.
[underlined] Frequency Range [/underlined] 4.3 to 6.7 m/cs all valves in Tx & Rx of 6.3 volts & indirectly heated.
[underlined] Power Supplies [/underlined] are by a small MG with either 12volt or 24volts input. L.T. for both Rx & Tx 6.3 volts at 2.3 amps HT for Rx 270volt at 35milliamps or Tx 250v at 65milliamps.
[underlined] Transmitter Portion [/underlined] - Crystal controlled Tx. no meters fitted. [deleted] R [/deleted] P.A. tuning indicated by illuminated lamp. (Maximum aerial current - maximum light.) The usually modulation test gives increase of light. 3 Valves.
[underlined] Receiver Portion [/underlined] is a 6 valve superhet. As with TR9 aerial coil & P.A. coil are common Only tuning in the set is the R.F. anode tuned circuit. Adjusted for maximum background. The RF oscillator is crystal controlled being [deleted word] 460 K/cs above or below the Tx frequency. The TF is therefore 460 K/cs.

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[underlined] General. [/underlined] Push button control giving 1 [deleted word] or 4 channels A. B. C. & D. 1/ "A" crystal in C.O; 2/ Select PA coil.'A'; 3/ Select 'A' crystal for R.F. oscillator; 4/ Select 'A' RF anode tuned circuit condensor. [underlined] T/R Switch [/underlined] is provided for switching from Tx to Rx. An intermediate position "RA" gives decrease of engine noise on no signal periods and intercom. [deleted word] Short fixed aerial
[underlined] Automatic Volume Control (AVC) [/underlined]

[diagram]

[underlined] AVC Bias to Grid of V/M valves [/underlined]

The diode in passing current in only one direction causes a PD across the resistance [symbol] as shown. This is applied as bias to the vari-mu valves, the signal [symbol] supplies its own bias, & the whole effect is to maintain the volume at a constant level. Unfortunately this means that weak signals [underlined] too [/underlined] are further weakened. To avoid this the diode has a delay [deleted] ed [/deleted] voltage applied to it so that it is necessary for the signal or voltage to exceed this voltage before the diode will conduct [symbol] only signals above a certain strength cause the A.V.C. system to work. This is called [underlined] delayed A.V.C. [/underlined]

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[underlined] [deleted] R 1155 Receiver [/deleted] [/underlined]
[underlined] [deleted] Communication Section [unreadable] [/deleted] [/underlined]
[underlined] The Superhet Principle. [/underlined]
[underlined] 2nd Channel Interference. [/underlined] As the I.F. occurs above & below the L.O. (ie/ both 1000 K/cs & 640 K/cs will produce an IF of 180 K/cs from [deleted] 1 [/deleted] 820 K/cs LO [symbol] the aerial must be selective enough to discriminate between the two signal frequency. We have seen that a higher value of I.F. greatly improves the position.
[underlined] Adjacent Channel Selectivity. [/underlined] Signals near to the frequency being received will also mix with the L.O. to produce a frequency sufficiently near to the I.F. to cause interference with it and [symbol] we need good selectivity in the signal frequency stages. - Hence the need for an R.F. Stage to give the required selectivity.

The mixer & the L.O. are put to-gether in a multiple valve called the frequency changer in order to obviate the feed back into the aerial causing self radiation. To enable C.W. to be received another L.O. is introduced into the detector stage called the beat frequency oscillator (B.F.O.) or heterodyne oscillator, which beats or mixes with the I.F. to produce an AF wave which is rectified & heard in the phones.

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[underlined] The Superhet Principle. [/underlined]

[diagram]

[underlined] R. 1155. Receiver. (Communication Section only). [/underlined]
A superhet receiver covering 18 M/cs to 75 K/cs for CW MCW & RT. [underlined] Ranges [/underlined] 1./ 18.5 to 7.5 m/cs 2/ 7.5 to 3 m/cs 1500 to 600 K/cs, 500 to 200 K/cs. 200 to 75 K/cs.
Dial directly callibrated [sic]. [underlined] Valves [/underlined] R.F. amp V/M Pent VR 100 F.C. VR99 Triode Hexode; 2 I.F. valves VR100 V/M Pent;
A.V.C. 1 Hext Osc. VR101 Double Diode Triode; Detector 1 Output VR101 DDT [underlined] Power Supplies [/underlined] - LT 6.3 volt (all IDH valve) H.T. 220 volts. Both supplied by M.G. - L.T. [deleted] G [/deleted] machine.
Automatic grid bias throughout.

[diagram]

BSD of communication section only. Receiver also contains D/F Valves.

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[underlined] Receiver Circuit. [/underlined] RF Stage for good selectivity. Tri/Hex frequency changer combines the function of RF oscillator & mixer in valve. The aerial tuned circuit, RF tuned circuit, & RF oscillator tuned circuit are each controlled by variable condensors. All these three are ganged to-gether for simplicity of operation. The IF is 560 K/cs. I.F. tuned circuits give good selectivity on both R/T & W/T. A D.D.T. is used as both HET oscillator & AVC valve. The triode portion has oscillation the frequency of which is 280 SK/cs. The 2nd Harmonic being used to provide the beat note for CW. The 2 Diodes of this valve both connected to-gether to provide A.V.C. Bias is developed across a tapped resistance & applied to the V/M valve, - Full AVC to the F.C. & I.F., a half to the RF amp, 1/10th to 2nd I.F. Bias Range negative 3 to 30 volts. The diode portion of another D.D.T. valve is used as a detector & the triode portion as output valve. A means of varying the input to the output valve by a potentiometer gives additional manual volume control.
[underlined] Difference between AVC and OMNI [/underlined]
On AVC the bias to the V/M valves is imposed [underlined] automatically [/underlined] by the strength of the signal on the AVC dial, whilst an additional manual volume control is available on the output valve stage. On OMNI the bias to the V/M valves is obtained by means of voltage developed from H.T. supply using a potentiometer giving a manual control instead of automatic. The additional manual volume control on output valve is out of circuit on OMNI. The two manual controls for AVC & OMNI are ganged to-gether but only one is operative at a time.
[underlined] Filter [/underlined] consists of a LF choke & condensor which cuts

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out interference from the ignition & generator.
[underlined] 1st Potentiometer - Manual - OMNI - Position. [/underlined]
Vary voltage of negative bias on the control grid of the 1 & 4 valves by means of a potentiometer - [underlined] manual volume control [/underlined] more bias - less [deleted word] amplification.
[underlined] The Triode - Hexode Valve. [/underlined]
Actually consists of two valves in 1 envelope with a common cathode. The triode portion is the LO. whilst the hexode portion used as the mixer. The S. Grid tied to earth prevents feed back & [symbol] no radiation takes place.

[underlined] How the 'Magic Eye' Works. [/underlined] Consists of a target anode coated with fluorescent material and a small triode valve, to the anode of which is connected a deflector, this protrudes to a hole in the target anode. When there is no signal on the grid the anode current in the triode valve will be high & [symbol] there will be quite an appreciable P.D. across the 1 mor resistance. The triode anode & hence

[underlined] VR99 1DH [/underlined]

[diagram]

the deflector is of lower potential than the target anode causing an electron shadow. [deleted word] With large negative bias on the grid from the AVC. diode then the anode decrea [missing letters]

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[underlined] The 'Magic Eye'. [/underlined] [underlined] VI 103 [/underlined]

[diagrams]

[diagram]

[underlined] WITH SIGNAL [/underlined]

[diagram]

[underlined] NO SIGNAL [/underlined]

and the PD across the resistance is quite small [symbol] the target & deflector are almost at the same potential & the shadow becomes smaller. Thus as the signal increases or decreases near resonance then the eye will open or close.

[underlined] Simple D/F Theory. [/underlined]
[deleted] To [/deleted] In order to get correct bearings we need not only direction, but (a) a sense of direction (b) position. We shall now see how it is possible to use radio for this purpose.
[underlined] Polar Diagram. [/underlined] Imagine the earth revolving on its axis [diagram] a/ [diagram] b/ Viewed from the top of the

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pole the earth would appear as figure 1/a/
This then is a polar diagram of the earth seen as a flat body. This represents direction & magnitude in that direction.
[underlined] The Polar diagram of a vertical Aerial. [/underlined]
With the aerial as centre and using a W63 as indicator we could find that the field strength was equal all round. Our polar diagram [symbol] be [diagram] [underlined] fig (b.). [/underlined]
Showing that the aerial radiates equally in all directions. The use of a polar diagram is to show pictorially the transmitting & receiving characteristics of an aerial. The two are synonymous [symbol] we see that the vertical aerial is [underlined] none - directional [/underlined] either [deleted] as [/deleted to [deleted] a [/deleted] transmitting or receiving a signal.
Considering the aerial [deleted] relative [/deleted] radiations as a solid body. Plotting the original radiations at all heights we should get something like this eg [diagram] - If this aerial is bent in the form of a ring [diagram] A B Section through that would give us our polar diagram.
[diagram] This is the characteristic of 2 aerials closely spaced, & is known as loop aerial & has the fundamental of D/F.
[underlined] LOOP AERIAL. [/underlined] Considering the loop as a [deleted] n wide [/deleted] receiver of waves from a transmitter with the loop pointing towards the transmitter - [diagram]
Similar EMF's will be induced into each aerial but as [deleted] one [/deleted] A is nearer to the Tx than B there will be more voltage induced in A than in B, this condition is further helped by the fact that the front aerial screens the back. These 2 E.M.F's being in the

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same loop will oppose each other, & will have a resultant of some definate [sic] PD which will cause current to flow if applied to an external circuit [diagram] Tx A B
[underlined] Introducing the Loop at Right Angles to the Magnetic Field [/underlined]

[diagrams]

EMF. will be induced equally in both aerials, & as [deleted] the [/deleted] A&B comprise the same loop they will oppose each other & cancel out completely. This gives us a very sharp zero position. The minimum is always used for D/F, due to this minimum being much more sharply defined than the maximum, & also to the fact that the ear is more susceptible to decreases of sound than to increases. [deleted] With respect to the [/deleted] The minimum position will occur again if the loop is turned to 180 [symbol] (called the reciprocal) and also if the Tx instead of being situated as shown, was on the opposite side of the loop. So although we have direction we have no indication of [underlined] sense of direction. [/underlined] In other words we cannot tell whether we are facing or have our backs to the Tx. (The effect is just the same if using maximum position).

There are two [deleted word] methods of finding [underlined] sense [/underlined] in the R1155. - One by means of an oral method
1/ (ie) using the phones 2/ by means of a twin pointer visual indicator.

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[diagram]

[underlined] SYNCRONIZED F/A AND METER SWITCHING [/underlined]

[underlined] Using the Visual Indicator. [/underlined] The fixed aerial is switched from one side to the other of the loop. The resultant rectified output from the Rx being switched simultaneously to alternate ends of the visual indicator, which is in effect a twin moving coil instrument with the common centre earthed. With the loop in the minimum position zero E.M.F. will be induced into it & the only E.M.F. applied to the Rx will be that from the fixed aerial. The E.M.F. applied to the meters will be equal, but opposite. Consequently each needle will rise by an equal amount, & will cross on centre line. With the loop offset the F/A voltages will oppose or assist that on the loop. Consequently one meter will receive more N than the other. Consequently one needle will fall & the other rise. The visual result is the needles collapse to the right or the left. (The loop & set D/F Receiver are made to conform to the universal rule.) (the T3 Rs rule). If [symbol] the loop is set [unreadable] ships then by turning the kite to the minimum position the needles will cross on the centre line & by keeping them so crossed the kite can find its way to the Tx [missing word/s] called 'HOMING'.

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[diagram]

[underlined] SIMPLIFIED D/F CIRCUIT R 1155. [/underlined]
[underlined] Operation of the F/A & Meter Switch. [/underlined] These are two triode hexode (VR99) valves to switch the F/A from side to side of the loop at a frequency of (a) 30 c/cs per sec (b) 80 c/cs per sec. A double-triode valve [underlined] VR102 [/underlined] known as a meter switching valve switches the rectified output to the twin meters, both switching operations being synchronised. There is a further valve known as the meter limiter which limits the input to the meter to prevent damage.

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[underlined] R1155 D/F CONTROL. [/underlined]
[underlined] Balancing of Visual Indicator. [/underlined] Before the visual indicator can be used it is necessary to ensure that the [deleted] F/E [/deleted] voltages [deleted] applied [/deleted] delivered to each side of the meter are identical which is accomplished by switching in a dummy loop, giving minimum position without possibility of pick up from an unwanted Tx & by matching the hexode sections of the T/H valves which is accomplished by suitably adjusting the HT applied to the relative screen. - Balance Control This ensures that [deleted] the [/deleted] equal voltages are delivered to the twin meters when the loop is in the minimum position.
[underlined] Meter Amplitude. [/underlined] is a variable resistance or rheostat [deleted words] connected between the common centre point of the twin meters & earth, which varies the current to the two meters causing an alteration in the height that the needles cross on the centre-line.
[underlined] Meter Deflection. [/underlined] The sharpness of the D/F bearing depends on the relative strength of the F/A to that of the loop. When the two are equal then the needles will collapse slowly, maximum deflection occuring [sic] when the loop is offset by 30 [symbol]. This is the point of low sensitivity. On high sensitivity part of the F/A voltages are bypassed & the needles collapse quickly, maximum deflection taking place when the loop is offset by 3 [symbol]. High is used for D/F bearings Low for Homing. - High sensitivity - Switch High.
[underlined] Speed Switch. [/underlined] Determines the speed at which the F/A is switched to the loop. Low being 30 c/s per sec 1.

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for R/T. High 80 c/s per sec for C.W.
[underlined] [unreadable] Sense Switch L/R. [/underlined] Disconnect manually the HT supplied to the (screen) S.Gs. of either hexodes, thus on either position of L or R one of the aerial switching valves is cut off, thus the F/A is applied by hand to either side of the loop. An increase of volume is noted when used in conjunction with the R.R.R. rule. Low frequency oscillator is now not in circuit.
[underlined] Type 3 Loop. [/underlined]
Is a loop aerial with 16 turns of wire to give the necessary inductance to cover the required M/F range on which it is used. As the loop in an aircraft is situated some distance from the set the output is fed through matched low loss type [deleted] if re [/deleted] shielded cable called " dulocapmet". The input to the Rx is provided with a small variable condensor for matching purposes. The loop is used with the normall [sic] [underlined] RRR [/underlined] method - Reduce scale readings or turn aircraft to right.
Needles move to the [underlined] R [/underlined] ight
Sense will be [underlined] R [/underlined] ight
The scale dial gives two scales, red & black. The red scale is not now used, black scale only being used with the R1155
The 1155 volume consists of 2 Potentiometers, only 1 of which is in circuit at any time. The first is OMNI which gives [deleted word] manual control of 1st 4 valves.

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[underlined] The R1155 Receiver. [/underlined]

[diagram]

[underlined] The T [deleted] R [/deleted] 1154 [/underlined]
High power G. Purp. transmitter covering 3 ranges of frequencies & with an increased power with that of the 1083. For C.W. M.C.W. & R/T [underlined] Frequency Range [/underlined] (1) Blue 10 to 5.5 m/cs (2) Red 5.5 to 3 M/cs (3) Yellow 500 to 200 K/Cs.
[underlined] Valves [/underlined] M.O. VT 105 I.D.H. Triode MOD VT 105 IDH Triode
P.A. 2 VT 104's in parrelell [sic] D.H. Pentodes.
[underlined] Power Supplies [/underlined] L.T. 6.3 from LT machine H.T. 1200v at 200 milliamps from H.T. machine.
Blocks Schematic Diagram.

[diagram]

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[underlined] [missing letters] ter Balance. [/underlined] A potentiometer connected between the 2 screen grids of the hexode portion of the 2 A/S valves.

[underlined] A Cardioid. [/underlined] Is the resultant diagram of the Fixed & Loop aerial together.

[diagram]

H.F. lower the inductance

The Aerial Plug - Board

[diagram]

[page break]

[blank page]

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[underlined] [missing letter] ransmitter Circuit Details [/underlined]

Hartley Oscillator used on all Ranges. Capacity coupled to two Pentodes in parellel [sic] forming the P.A.
P.A. tuned circuit controlled by variable condensor on red & blue ranges & by iron core on yellow range. On [underlined] Blue [/underlined] range the anode tap is preset and needs no adjustment. On [underlined] Red [/underlined] range two alternate anode taps are available either of which can be preset. On [underlined] yellow [/underlined] range the anode tap is by a tapped inductance (18 to 34) The aerial taps on all 3 ranges have variable taps on the coil marked 1 to 9 on the red blue and [deleted] of [/deleted] 1 to 17 on the yellow range.
[underlined] Modulation. [/underlined] Suppressor grid modulation is affected on the PA Stage by a VT 105 modulator for R/T. For MCW the modulator valve becomes an oscillator at 1200 c/s per sec.
[underlined] Keying. [/underlined] is affected in the normal way paralising [sic] bias being imposed on the valves M.O. & PA when key is lifted.
[underlined] Side tone [/underlined] is available for C.W. M.C.W. and R/T. On CW & MCW it is provided by the modulator valve giving A.F note. On R/T is provided by (a) modulator valve when using carbon mike (b) A1134 when using E.M. mike.
[underlined] Listening Through. [/underlined] is affected by key relay giving 2 positions, send & receive.
[underlined] Master Switch & Key Relay [/underlined] [deleted] on [/deleted] [circled 1] off [circled 2] Standby
[underlined] L.T. machine started [/underlined] giving 6.3 to heaters of all valves Tx and Rx. & 220 volts to Rx. [underlined] Key Relay [/underlined] energised in receive position which connects H.F. & M.F. aerials and phones to Rx. [circled 3] Tune. H.T. machine & tested giving 1200V to Tx. With [underlined] key up [/underlined] relay in receive positions & paralising [sic] bias applied to MO. & PA. With [underlined] Key Pressed [/underlined] relay in send
control grids

[page break]

position the MF & H.F. aerials connected to Tx; Phones connected to side-tone; Paralising [sic] bias shorted.
Suppressor Grid negative 50 volt giving half power output when setting up. [circled 4] C.W. [underlined] Key Up [/underlined] (same as tuned) [deleted word] [underlined] Key pressed [/underlined] as tuned but now positive 50v on suppressor grids of PA's giving full power. [circled 5] M.C.W. [underlined] Key up [/underlined] (same as tuned) [underlined] Key pressed [/underlined] same as tuned including negative 50v bias. The P.A. is now modulated at 1200 c/s per sec. [circled 6] R/T Key must be strapped down exactly as tuned, but P.A. now modulated at special frequencies.
Fuse in front of set fitted in HT positive line, rated at 750 milliamps.
Input meter called mag feed & MF aerial current meter fitted in the set. H.F. aerial meter fitted externally.

[diagrams]

[underlined] TYPE "J" SWITCH [/underlined]

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[underlined] Aerial Plug Board [/underlined] gives convenient method of connecting the output from the set to the aerial system or artificial aerial required. [deleted word]
[underlined] Type "J" Switch 5 Positions & 4 Uses. [/underlined]
[underlined] Normal [/underlined] A/. MF to trailing aerial.
B/ H.F. to short fixed aerial.
[underlined] Emergency [/underlined] MF on fixed or HF on trailing
[underlined] D/F[/underlined] Correct (Fixed) aerial connected to aerial switching valve. The HT machine is cut off & [symbol] the Tx will not work.
[underlined] Electrical Storms [/underlined] All aerials earthed.

[underlined] Click Stop Tuning Red & Blue Range [/underlined]
[underlined] M.O. [/underlined] 1/ Set vernier adjustment to 2nd division from the bottom. 2./ Slacken screw opposite letter in use. 3/ Find appropriate ring at back of control & engage its projection into the click stop. Rotate M.O. control to frequency desired. Tighten screw.
[underlined] P.A. [/underlined] 1/ Slacken screw opposite same letter as was used on M.O. Without click stop mechanism tune P.A. in normal manner. Mark the ivory scale to give correct P.A. setting. Engage click stops & rotate appropriate projection until it engages in the mechanism. Rotate PA. control to pencil line setting, press the key & check that this is correct. Tighten screw opposite letter in use. Fill in chart on front panel giving frequency & aerial tap number.
[underlined] Yellow. Range. [/underlined] Set up M.O. as for red & blue range. Tune P.A. in normal manner & mark the ivory scale to give the setting,

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remember to put the letter in use on the M.O. opposite the mark. [underlined] N.B. [/underlined] Both aerial and anode tap numbers must be put on the chart.

[underlined] Marconi G.P. Equipment T.1154/R1155. [/underlined]

[diagram]

[underlined] L.T. [/underlined] INPUT 18v 13 amps OUTPUT 7v 13 amps 220v 110 [unreadable]
[underlined] HT. [/underlined] INPUT 24v 16amps OUTPUT 1200v 200 AV amps
[underlined] M.G. [/underlined] HT 220V LT 6.3V. Type 34 input 12v Type 35 input 24v

[underlined] Tuning on Blue & Red ranges [/underlined] set M.O. to correct frequency wave change switch in correct position, turn P.A. variable condensor fully anti-clockwise, aerial tap switch on no. 1 position. Press key rotate P.A. condensor in clockwise direction for minimum input (1st clip). Release key and switch to tap no. 2 retune for minimum. Continue doing this until minimum input comes up to, but not exceeding the green line. Switch to C.W. position press key and make sure the input needle is [underlined] not [/underlined] on the red portion of the scale. If needle is on red, reduce by going back one tap. When on CW if aerial current meter reads over 4 amps switch out of [missing word]

[page break]

[underlined] Tuning on Yellow Range. [/underlined] Set M.O [deleted] O [/deleted] variable condensor to correct frequency. Permeability tuning in the centre and taps showing letter V position. Press key & notice reading in input meter. Then reduce aerial tap switch tap by tap to get minimum input, each time testing with the permeability tuning to see if you have the dip. (Like the TR9) Having found the minimum position then bring up the (lowest possible) minimum up to the green line by using the anode tap on the tune position. Over to CW. and check as before.

[underlined] TR 1196. [/underlined] (see notes)

[diagram]

[page break]

[underlined] Motor Generators [/underlined]

(a) Type (b) INPUT (c) CURRENT (d) OUTPUT (e) CURR [missing letters]
(a) 34 (b) 10.5v (c) 24A (d) 220 v (e)110 ma [missing letters]
(a) 35 (b) 18v (c) 12A (d) 6.3v (e) 13 amps
(a) 32 (b) 12v (c) 32A (d) 1200v (e) 200 mamps
(a) 33 (b) 24v (c) 16A

[diagram]

[underlined] VR 57 OCTODE [/underlined]

Collection

Citation

Malcolm Staves, “Malcolm Staves' Notebook for Wireless,” IBCC Digital Archive, accessed April 13, 2024, https://ibccdigitalarchive.lincoln.ac.uk/omeka/collections/document/11382.

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