Malcolm Staves' Notebook on Lecture Technique and Radios

Malcolm Staves' Notebook on Lecture Technique and Radios

Notes written by Malcolm Staves during his training as a wireless operator.

One notebook with handwritten annotations

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MStavesME203137-160226-24

M.E. Staves Course 32.
[underlined] ME Staves [/underlined]
[underlined] B.C.I.S. [/underlined] FINNINGLEY
[underlined] “GEN” [/underlined]
ROYAL AIR FORCE
Notebook for use in Schools.
[underlined] 1st 2nd [/underlined]
[underlined] 66% 80% 66% 60% [/underlined]
[page break]
[blank page]
[page break]
[underlined] Lecture Technique [/underlined]
[underlined] Instruction [/underlined]
Presentation
Introduction – Links with previous knowledge
Development – Logical Step
Conclusion – Revisional – Survey
Ensuring Comprehension
Interest – Attitude – Manner – Voice
Class Co-op – Q’s & Discussion
Consolidation – B.B. Summary – Diagrams etc – Notes
[underlined] Aim [/underlined]
[page break]
[underlined] Preparation [/underlined]
[underlined] Matter [/underlined] – Aim – Pupil – Time – Amounts
[underlined] Confidence, Allocation of time. Efficient Instruction [/underlined]
[underlined] Method [/underlined]
Orderly Procedure
Use all Aids – Comparisons – Example – Analogies – Points from Personal Exp.
Summaries – Diagrams – Demonstrations
Sequences
Introduction – Arouse desire to learn – Link with previous Knowledge – Factual – Dramatic – [underlined] Statement of Aims [/underlined]
Development – Asume [sic] very little – logical steps. – (Use construction operation) – Consolidate brief incidental Revision
Conclusion – Summaries – Q’s & Discussion – Exercises – Revisional Survey
Guide to amount learnt
Guide to starting point of next lesson
[page break]
[underlined] Written Preparation [/underlined]
[underlined] Notes: [/underlined]
[underlined] Need [/underlined]
Aid to Efficiency – Show up: Inconsistencies x – [indecipherable word] Transitions – Main Q’s – Means of Reference
[underlined] Style [/underlined]
Depends on: - Personal taste. – Subject: Class Matter & Method.
[underlined] Matter [/underlined]
In rough first. – All points: list of apparatus etc. B.B. summary clearly known. Diagrams down
[underlined] Aim [/underlined]
i.e. Statement. Problem. Q
[underlined] Method. [/underlined]
Some Q’s in full – Illustrations – Key words. – Order of copying diagrams etc.
[page break]
[underlined] Construction & Action of a Mechanism [/underlined]
[underlined] Introduction [/underlined]
[underlined] Development [/underlined]
Purpose and Use. (How it has developed).
General Survey of whole apparatus
Main Parts
Details
Discussion of advantages & disadvantages. limitations ranges etc. Uses.
[underlined] Conclusion [/underlined]
Run through construction & action (brief a student)
Deal with Q’s from class
Discuss practical uses.
[page break]
[underlined] Theory Lesson. [/underlined]
[underlined] Introductions [/underlined]
State the problem. See if what the purpose & value of the solution is.
[underlined] Development. [/underlined]
Examine the main factors involved
Reason each step separately, using as far as possible previous Knowledge possessed by class
Illustrate with examples.
[underlined] Conclusion: [/underlined]
Practical exercises.
[page break]
[underlined] Presentation [/underlined]
[underlined] Personality [/underlined]
Attitude
Manner – Bearing
Voice
[underlined] Classroom Conditions [/underlined]
Lighting
Heating
Ventilation
[underlined] Be [/underlined]
Confident
Vital. Patient
Interesting
[underlined] Class Management [/underlined]
Self Discipline. Tact
Punctuality
Equal Temper
[underlined] Instructional Speech [/underlined]
[underlined] Clear Speaking [/underlined]
[underlined] Voice [/underlined]
Good Articulation
Correct Speeds
Pauses
Emphasis
[underlined] Choice of Words [/underlined]
Simplicity
Precision
[page break]
[underlined] Class Co-operation [/underlined]
[underlined] Practical [/underlined]
Use of Apparatus
Experiments. Examples
[underlined] Written [/underlined]
Pupils own notes [underlined] inadvisable [/underlined]
BlB. Summary to be amplified
Duplicate Notes
[underlined] Oral Work [/underlined]
Q’s & Answers
[underlined] Use [/underlined]
Revision
Explanatory
General: to test
Application of Knowledge
[underlined] FORM. [/underlined]
Clean: Simple
No catches
No YES-NO types
Limit [inserted] the [/inserted] Scope
[underlined] CHARACTERISTICS. [/underlined]
Clarity: Simplicity
[deleted] A [/deleted] Limiting
Admitting of [underlined] one [/underlined] answer
To sustain interest & provoke thought.
[underlined] ANSWERS. [/underlined]
Sympathy
Patience & Tact. Use names last.
Allow time
[underlined] NO [/underlined]
Repetitions
Interruptions
Sarcasms
[underlined] Q’s from CLASS [/underlined]
Invite them at proper stage
Deal with them honestly.
Always provide an answer
[page break]
[underlined] Blackboard Work. [/underlined]
Visual Aid
[underlined] Clarity [/underlined]
Position
Writing – Drawing.
Printing
[underlined] Unity [/underlined]
[underlined] Emphasis [/underlined]
[underlined] Simplicity [/underlined]
Choice of words
Layout
[underlined] Summaries [/underlined]
[underlined] Types [/underlined]
Headings
Tree
Tabulated
[underlined] Use [/underlined]
Pegs
Progressive
Revision
[underlined] General Points [/underlined]
Clear at Start
Short Intervals
Avoid Restlessness
Look at Class.
Illustrate No mistakes.
Preparation & Practice
[underlined] Diagrams [/underlined]
[underlined] Types [/underlined]
Temporary
Annotated
Graphs
[underlined] Const. [/underlined]
Visualise
Complete
Main comp’nts first
[underlined] Use [/underlined]
Build up with talk on product ready for use
[underlined] Other teaching Aids (cont) [/underlined]
[underlined] 2 Epidiascope [/underlined]
[underlined] 3. Demonstration Model [/underlined]
[underlined] 4. Actual Apparatus [/underlined]
[underlined] 5. General [/underlined]
(a) Be sure when to use it
(b) Show appreciation of the size.
[underlined] 6 LIBRARIES [/underlined]
(a) Good Cataloguing & clean references.
(b) Fix a period of loan.
(c) Good facilities for occas’il [sic] references
(d) Periodic Checks.
[page break]
[underlined] The Revision Lesson [/underlined]
Mainly through Q’s & examples
Stick to main points.
Q’s & Examples will follow the same general order as in the original lesson.
[underlined] Teaching of a Skill [/underlined]
[underlined] Introduction: [/underlined]
Arouse interest & demonstrate completely
[underlined] Development [/underlined]
[underlined] 1. [/underlined] Demonstrate carefully with full explanations
[underlined] 2. [/underlined] Take first section; demonstrate. Individual practice: errors corrected, further practice.
[underlined] 3. [/underlined] Proceed similarly with each section of the operation.
[underlined] 4. [/underlined] Combine stages to-gether [sic] until whole operation is learned.
[underlined] Conclusion [/underlined]
Illustrate practical use & give opportunity for use.
[underlined] Other Teaching Aids [/underlined]
[underlined 1 Mechanical [/underlined]
[underlined] a [/underlined] Synchrophone: Has definite revision use
[underlined b Films. [/underlined]
[underlined] I [/underlined] Preview – make notes
[underlined] II [/underlined] Normal run with class.
[underlined] III [/underlined] Discussion.
[underlined] IV [/underlined] Final Run.
[page break]
[underlined] Learning & Memory [/underlined]
Rapid Learning Permanent Retention Ready Accessibility
[underlined] Psychological Factors [/underlined]
[underlined] Attitude [/underlined]
Confident enthusiastic
Problem solving
Attract Attention
Retain with Interest
Sustain interest with varied activity
[underlined] Motives [/underlined]
Evidence of progress
Self-competition
Praise.
[underlined] INTEREST [/underlined]
[underlined] AIDS [/underlined]
Learn by wholes
Examine by results
Associations
Recapitulate, Rest, Revise
No fatigue
Imaginery [sic] (Vis And Misc).
No distractions
Goal to be seen & be attainable
[underlined] Kinds of Learning [/underlined]
[underlined] Initiative [/underlined]
Attitudes “picked up” in this way
All skills at first
[underlined] Rate [/underlined]
Mechanical skills
Learning by heart
Dispense with [underlined] rate [/underlined] by written recording of facts.
[underlined] Rational [/underlined]
Most important
Meaning. Associations
Psych factors –
[underlined] CONCENTRATION [/underlined]
[page break]
[underlined] Instructional Organisation [/underlined]
[underlined 1. Planning a Course [/underlined]
Bear in mind (Intro: Devt: Consolidation)
[underlined] 2. Time Tables [/underlined]
[underlined (a). [/underlined] Least elastic factor
[underlined] (b) [/underlined] Distribute subjects.
[underlined] (c) [/underlined] Bear in mind learning value of periods.
(d) Allow for breaks
[underlined] 3 Instructor’s Records [/underlined]
(a). Lecture Notes.
(b). Record of Work Done.
(c). Record of Tests.
(d). Charts of Progress Etc.
[underlined] 4. Tests [/underlined]
(a) Aim is to test – sample.
[underlined] 5. Setting of Tests [/underlined]
[underlined] (a). [/underlined] Clarity of Q.
[underlined] (b). [/underlined] Main points. Whole of section to be covered.
(c). Sufficient easy Q’s to enable the average pupil to pass. A few harder ones to bring out the better pupils.
[underlined] (d). [/underlined] Instructions must be clear.
[underlined] 6. Types [/underlined]
(a). Set Q’s which involve factual answers.
(b). “ “ “ require a diagram.
[page break]
[underlined] Instructional Organisation [/underlined] (cont).
[underlined] 7. Questions [/underlined]
(a) Arrange that the answers demand effort proportional to marks allotted.
(b) State which diagram is required.
(c) State what kind of definition.
[underlined] 8. Assessment & Use of Results [/underlined]
(a) Explain the System.
(b) Severity represses. Leniency tends to forfeit respect.
(c). Watch grading (Distribution Course)
[underlined] 9. Orals [/underlined]
(a). Intending Instructors.
(b). Border line cases.
(c). Practical Subjects.
(d) Use cards with Q’s taken from the whole syllabus.
[underlined] 10. Recording [/underlined]
Question – Points expected – Max marks obtainable – Marks Obtained
[page break]
[blank page]
[page break]
[blank page]
[page break]
[underlined] Marconi Fault Finding [/underlined]
[underlined] AMP 180 [underlined] Good Gen Book
[underlined] R1155. Valves [/underlined]
[diagram]
[underlined] Valves U/S. – SYMPTON – REMEDY [/underlined]
[underlined] V3 RFA VMB. TET [/underlined] - No (weak possible Signals Loud 280.5 K/C note – Magic Eye Deflects to this signal only. - [underlined] 1 [/underlined] Short out V3 – learned grid to [underlined] V4 [/underlined] for Sensitivity. (Amplification) [underlined] 2 [/underlined] Replace V3 by V5 & start V5’s cap on to V6 for Selectivity
[underlined] V4. F.C. TRI/HEX – No Signals No 280 K/cs note Magic Eye will not Deflect – Replace by V1 on V2
[underlined] V5. 1st IF VMB TET OR V6 2nd IF. VMB TET [/underlined] – Weak Signals-Weak 280.5 K/CS note-No Magic Eye Deflection – Detect U/S valve (50-6)-Put Serviceable valve in V6’s position & short out V5 stage.
[underlined] V8 D&O. DDT. [/underlined] – No Signals. Magic eye Deflects normally. No 280 K/cs note – Replace with V7. and Remove Screening cans from V5 & V6 Replace V8 with V10 (ME) [indecipherable word]
[page break]
[underlined] Emergency Turning [/underlined] (without M.E) Middle Jones Plug in Rx [symbol] Phones to 2nd pin on left (going up). Time for “Dead Space”.
[underlined] Values U/S. [/underlined]
[underlined] V7 DDT BFD [/underlined]
[underlined] Sympton [/underlined]
No Magic Eye Deflection
Only MCW & R/T Signals received. No 280 K/cs Note.
[underlined] Remedy [/underlined]
Change V8 with V10 & place V8 in V7’s position.
[underlined] T1154 Valves [/underlined]
[diagram]
[underlined] P.A. Valve Emission Test [/underlined]
[underlined] 1. [/underlined] Remove either V2 or V3.
[underlined] 2. [/underlined] Select Yellow Range. Taps selected 17 & 18, Fine Tuning control fully anti-clockwise. M.O. set at 500 K/[underlined]cs[/underlined] Remove M/F Aerial (side of Tx).
[underlined] 3. [/underlined] Press key on Tune.
[underlined] Valves U/S – Sympton – Remedy [/underlined]
[underlined] V1. [/underlined] – Mag Feed above normal No dips on amp range – Replace with V4.
[underlined] V2 and V3 [/underlined] (together) – No Mag Feed reading. – NIL.
[underlined] V2 or V3 [/underlined] – Low Mag Feed – Check valves by/ “Emission Test” and [underlined] remove [/underlined] U/S valve.
[underlined] V4 [/underlined] – No Side-Tone – NIL
[page break]
[underlined] 4. [/underlined] Observe Mag Feed reading – Should be 190 [inserted] or above [/inserted] on S valve.
Will be 120 or below for U/S valve.
Soft P.A. valve reads 300 ma or over (blue lights)
[underlined] Power Supply Shorts to Earth [/underlined]
6.3v – Already Earthed at LTP.U – No change
6.3v + Dead short across 6.3v brushes of LTPU – [underlined] Input/use blows. [/underlined]
220v – On [symbol] and 00 full gain on Rx. No volume control – bias network is shorted out.
[underlined] AVC. Balance Vis. [/underlined] Almost normal, but no 3.6v negative safety bias.
220v + Full H.T. across Biasing network R1. R3. and R4. Burn out.
1200v – to earth – Permanent input in the Mag feed. Meter Key up or key down. (No paralysing Bias).
1200v + to earth – Key up – nothing happens. Key down – 750 ma fuse blows.
[page break]
[underlined] VHF – 5043 [/underlined] T.R.
[underlined] Advantages [/underlined]
[underlined] 1. [/underlined] Above frequency of Natural Static.
[underlined] 2 [/underlined] Short ground wave [symbol] Security.
[underlined] 3 [/underlined] Unaffected by the Heaviside Layer.
[underlined] 4. [/underlined] Accurate D/F up to maximum Range by Day & Night.
[underlined] 5. [/underlined] Large Frequency Coverage allows good station separation.
[underlined] 6. [/underlined] 1/4 wave aerial quite short and easily fitted.
[underlined] Disadvantages [/underlined]

[underlined] Frequency Coverage. [/underlined] 100 TO 156 M/cs
[underlined] Range varies with Height [/underlined] – 30 mls at 1000 ft.
- 180 mls at 20000 ft
(approx. max.)
[underlined] Txmitter Output [/underlined] 8 to 9 Watts.
[underlined] 4 Preset Frequencies [/underlined]
[page break]
[blank page]
[page break]
[blank page]
[page break]
[underlined] TR. 1196 (VHF in Bomber C) [/underlined]
[underlined] Intro. [/underlined] Took the place of the TR9 & was designed for the F.A.A. as an R/T & MCW. Tx Rx. Later it was adapted for use in multi-seater A/C. in conjunction with the A1134A. Advantages over TR9. – Superhet. Better Ranges. Has 4 Freq [deleted] Ranges [/deleted] [inserted] Channels [/inserted]
[underlined] DEV [/underlined]
Self contained unit Tx & Rx.
[underlined] Freq coverage. [/underlined] 4.3 to 6.7 M/cs
[underlined] Ranges [/underlined] Air to Air 30 mls
Air to Ground 50 mls
[brackets] At 2000 ft (“c” & “D”. 8 to 10 miles) [brackets]
[underlined] Power Supplies [/underlined]
LT 6.3v 1.3 amp HT 250v 65.ma FROM Motor Generator which is driven from the A/C G. electric (Input 24v) 2.6amp ([underlined] System [/underlined]
[underlined] General [/underlined] 4 X stal controlled frequencies – selected one at a time by Push Buttons on Controller Electric. Marked A.B.C.D.
[underlined] Tx BLOCK DIAGRAM [/underlined]
[underlined] (AB – 1-8 watts CD - .8 watts) [/underlined]
[underlined] M.O. Stage [/underlined] – VR9L PENTODE.
Circuit is a Pearce Ose CCt and is Quartz X stal Controlled. One of 4 X stals is selected by the Step by step motor in the chassis assembly (Grid Leak & condensor [sic] Bias)
[underlined] Advantage [/underlined] & [underlined] Freq Stability [/underlined] of 1 part in million can be maintained over long periods in good conditions with temperature control. (In T1154 freq could drift owing to “mechanical vibration”.
[page break]
MO. coupled to PA. via a condenser (as in T1154)
[underlined] 2 PA Stage VT501 TETRODE [/underlined]
Amplifies oscillations produced in M.O. Consists of timed cct & valve. 4 Tuned ccts each a “Continuously Variable Inductance” with “Aerial & Earth” as [inserted] the [/inserted] “Capacity”. One of these ccts is selected at each position of the step by step motor.
(([underlined] High Power Output [/underlined] is obtained by operating the valve as a [underlined] Class “C” [/underlined] Amplifier))
[underlined] Resonance [/underlined] while [underlined] tuning [/underlined] the P.A. stage is indicated by a low power lamp in the Aerial circuit, which is normally shorted out by a spring plunger.
[underlined] “C” Range “D” [/underlined] The power of the Tx is reduced on these ranges, to give the necessary [indecipherable word] range of 10 mls. Done by inserting an 1800 ohms resistor in the AE cct of this range.
[underlined] MODULATOR STAGE VT52 PENTODE [/underlined]
Acts as an A/F Amplifier whose [inserted] A/F [/inserted] output is passed on to the P.A. valve. ((Anode Choke Modulation explained later))
[underlined] COMMON AE CCTS [/underlined]
Before going any further we have to feed the signals from our P.A. on to an aerial, and in this case we use a “Common Aerial [indecipherable word] for Tx & Rx [/underlined]
[page break]
[underlined] 3 [/underlined]
The [underlined] PA tuned [/underlined] cct forms the [underlined] Grid [/underlined] cct of the [underlined] R.F. Amplifier [/underlined] in the Rx [symbol] it is necessary to tune the Tx [underlined] before [/underlined] tuning the Rx.
[underlined] So much for Tx valves [/underlined] But in 1196 we use A.F. stages of our Rx as a sub-modulation for Tx. They are [underlined] V5. [/underlined] & [underlined] TRIODE [/underlined] Portion of [underlined] V6. Put in ON BB. [/underlined]
[underlined] ANODE – CHOKE MOD. [/underlined]
[underlined] Andio Freq [/underlined] input from mikes after Amplification in the AF Stages of the Rx is applied, to the [underlined] control grid of [/underlined] the [underlined] Modulation.V. [/underlined] The Anode load of our Modulator valve is in this case a [underlined] TAPPED CHOKE [/underlined]
VOLTAGE VARIATIONS [inserted] FED [/inserted] ACCROSS [sic] [deleted] [underlined] A.S.C. [/underlined] [/inserted] B.C. ARE AMPLIFIED ACCROSS [sic] A [deleted] [underlined] B.S. [/underlined] [/deleted] C. DUE TO [underlined] AUTO-TRANS ACTION. IN THE CHOKE [/underlined]
((REVISE)) [diagram] 50v [underlined] Input 25v Output 50v [/underlined]
THE AUDIO SIGNAL WHICH IS THEN PASSED INTO OUR P.A. ANODE CCT. IS AN ALTERNATING VOLTAGE WHICH PERIODICALLY [underlined] ADDS [/underlined] OR [underlined] SUBTRACTS [/underlined] FROM THE FIXED H.T. VOLTAGE. THE VARIATIONS IN ANODE POTENTIAL THUS RESULTS IN THE PRODUCTION OF A MODULATED AE CURRENT.
((VARY THE ANODE & SCREEN VOLTAGES OF OUR P.A. VALVE AT MODULATION FREQ))
[page break]
[underlined] IF TIME RUN OVER N/E. SWITCH [/underlined]
[underlined] Conclusion [/underlined]
Q’S ON ALL LESSON. & FILL IN SPACES ON BOARD.
([underlined] ON NORMAL [/underlined] (For Reception.)
A1134A amplifies the output from the Detector of V6 to the Phones. Amp. portions of V5 & V6 not used.)
[underlined] On Emergency [/underlined]
When A1134A fails. Output of V6 TRIODE is [deleted] at [/deleted] connected to PHONES & with mike input fed to Transformer makes V5 & V6 act as if comp. [underlined] ON N [/underlined]
[underlined] NB [/underlined] THE A1134A [underlined] Does NOT [/underlined] AMPLIFY THE MIC INPUT TO. TR1196.
[diagram]
[page break]
Class “C” Amplification
[diagram]
[underlined] TUNING [/underlined]
[diagram]
[page break]
[blank page]
[page break]
[underlined] Lancaster Electrical Layout [/underlined]
[underlined] 2. Generators S.I. & P.I. [/underlined]
[diagram]
[page break]
[underlined] SCR 578 “GIBSON GIRL”. [/underlined]
[underlined] General Details. [/underlined]
Automatic Code Tx (500 K/cs)
Signal lamp incorporated.
[underlined] Power Supplies [/underlined]
300v HT. 28v LT. Hand driven Generator.
[underlined] Valves [/underlined]
Audio Oscillator & Amp 12 SC
RF Amplifier 12A6
[underlined] Tuning Control (PA).
Radio/Light Switch
Key
[underlined] Aerial [/underlined] 300 ft long
[underlined] Range [/underlined] 250 to 500 miles
[underlined] Dessicant Silica Gel [/underlined] (Dampness)
[page break]
[underlined] “Walter” Tx3180 [/underlined]
Freq. 176 Megs
Mast Aerial 7 ft 6 ins (Current consumption 120 ma.)
Power Supplies 90v HT. 1.5v LT. (2 1.5v in Parallel) (3.30v in Series)
Weight 2lbs 10ozs.
[underlined] Ranges [/underlined]
4 mls A/c flying at 50 ft
10 mls “ “ “ 250 ft
14 mls “ “ “ 500 ft
18 mls “ “ “ 1000 ft
20 mls “ “ “ 1500 ft
[underlined] 25 [/underlined] mls “ “ “ 5000 ft
[underlined] Operation [/underlined]
[underlined] 1 [/underlined] Fix Weather Apron [underlined] 2 [/underlined] Tear off wrapper.
[underlined] 3 [/underlined] Pull out guy lines & fix to dinghy rings
[underlined] 4 [/underlined] Erect AE mast ensuring that each section clicks home.
[underlined] 5 [/underlined] tighten guy lines. [underlined] 6 [/underlined] Switch On
[inserted] Normal conditions [/inserted]
Life of Battery [underlined] 20 [/underlined] hrs. In Tropical & Arctic conditions [underlined 8 hrs [/underlined]
Valve used is a TRIODE CV 91
[underlined] SQUEG FREQ [/underlined]
35 to 60 K.cs
[page break]
[deleted] M.O.
To generate signal into Tx
Variable condenser
3 tuned circuits for 3 diff ranges
Hartley Oscillator
{symbol] [/deleted]
[page break]
[underlined] DELAYED AVC. [/underlined]
[diagram]
[underlined] Straight Rx Disadvantages [/underlined]
[underlined] 1. [/underlined] Poor Sensitivity.
[underlined] 2. [/underlined] Poor Selectivity.
[underlined] 3. [/underlined] Poor Stability (Liable to go off into self-oscillation).
[underlined] 4. [/underlined] Complex tuning (More tuned circuits).
[underlined] Supersonic Heterodyne Rx [/underlined]
[diagram]
SUPERHET
SENSITIVITY
SELECTIVITY
STABILITY
SIMPLICITY
[page break]
[underlined] Basic Receivers [/underlined]
[diagram]
[underlined] Rx for R/T & MCW [/underlined]
[underlined] AVC. [/underlined]
[underlined] Simple [/underlined]
[diagram]
[underlined] Delayed AVC. [/underlined]
[underlined] (See over) [/underlined]
[page break]
[underlined] Valves [/underlined]
[diagram]
[flowchart]
[diagram]
[flowchart]
“Alligned Grid Tetrode”
“Beamed Aligned Grid Tetrode” [diagram]
[underlined] Vari – Mu Valve [/underlined] (Variable Amplification).
[underlined] 1 [/underlined] Open & closed wound control grid
(Put large – potential on grid to stop valve working)
(Smooth volume). Long Grid Base
[flowchart]
[page break]
[underlined] Simple Tx Disadvantages. [/underlined]
[underlined] Frequency Drift [/underlined]
[symbol]
[underlined] Covercone [/underlined] by [circled 1] Use of [underlined] MO/PA [/underlined] Tx.
[circled 2] Screening MO. [circled 3] Low power on M.O.
[circled 4] I.D.H. MO. Valve.
[circled 5] Parts of Low co-efficient of expansion.
[circled 6] Smooth Power Supplies.
[diagram]
[underlined] KEYING BIAS. [/underlined]
[diagram]
[underlined] Cathode Bias. [/underlined]
[diagram]
[page break]
Class “C” Amplification twice the voltage from cut off point.
[diagram]
[underlined] Triode as an Oscillator [/underlined]
Messner Oscillator
[diagram]
Automatic Bias – Grid leak [symbol] condensor [sic]
[underlined] Simple Tx [/underlined]
[diagram]
[page break]
[underlined] Open Oscillatory Circuit [/underlined]
[equation]
[diagram]
[underlined] Increase [/underlined] Inductance on Capacity. Frequency [underlined] Decrease. [/underlined]
[underlined] Decrease [/underlined] “ “ “ “ [underlined] Increase. [/underlined]
[underlined] Valves [/underlined]
[diagram]
[underlined] Thermionic Valve [/underlined]
[flowchart] [diagram]
[flowchart] [diagram]
[flowchart]
[underlined] Class A. [/underlined] Amp.
Halfway between Ovals & cut off point.
[underlined] Class “B” [/underlined] around cut off point.
[page break]
[underlined] Formula. [/underlined]
K = Dielectric (ie. Air = 1) (Mica = 6) (Sulpher = 4)
A = Area of overlap of the plates in [symbol] cms.
N = Number of Dielectrics.
D = Thickness of Dielectric. (cms)
Affect in D.C. current = Blocking condensor [sic] (Blocks D.C.).
“ “ A.C. current = [underlined] Appears [/underlined] to pass A.C.
[underlined] Condensors [sic] in Parallel. [diagram] [formula]
[underlined] Condensors [sicv] in Series [diagram] [formula]
[diagrams]
[flowchart]
[page break]
[underlined] Lenz’s Law [/underlined] = Induced EMF.’s act in such a direction as to oppose the direction to which they are due
[diagrams]
An [underlined] Inductance [/underlined] opposes a change in direction of current flow.
[underlined] Unit of Inductance is HENRY. [/underlined]
1 Henry = When the current changes at the rate of [underlined] 1 amp per sec [/underlined] the self induced E.M.F. is [underlined] 1 volt. [/underlined]
[underlined] The Condenser [/underlined]
[underlined] Unlike [/underlined] Poles Attract
[diagram]
[underlined] Like [/underlined] Poles Repel.
[diagram]
[underlined] Capacity of Condenser [/underlined] – [underlined] FARADS. [/underlined] – A charged body has a capacity of [underlined] 1 Farad [/underlined] if it raised to a potential of [underlined] 1 volt [/underlined], when given a charge of [underlined] 1 Ampere. [/underlined]
[underlined] Formula. [/underlined] [formula]
[page break]
[underlined] Resistors [/underlined] – [underlined] Series [/underlined] [diagram]
[equation]
[diagram]
[underlined] Parallel [/underlined]
[formulae]
[underlined] Total Resistance [/underlined] is lower than the least resistance in parallel.
[underlined] Coils and Inductances [/underlined]
1. Magnetic Effect. When current passes through a piece of wire [diagram]
[underlined] Faradays Law. [/underlined] says whenever the magnetic flux in a circuit changes an EMF is produced. This E.M.F. directly proportional to the rate of change of the flux.
[diagrams]
[page break]
[underlined] Simple Electrical Units. [/underlined]
[underlined] Water – Type – Electrical [/underlined]
Gallons – Quantity – Coulombs. (10’9 Electrons)
Gallons per minute – Current. – Amperes. (1 coulomb past a point in 1 sec)
Lbs. – Resistance – Ohm (the resistance offered to an electrical current by a standard column of mercury)
Lbs per square inch. – Pressure – Volts (Amount of [inserted] potential [/inserted] pressure needed to maintain 1 amp through 1 Ohm.
[underlined] Sub Multiples. [/underlined]
MICRO – 1/1,000,000
MILLI – 1/1,000
[underlined] Multiples [/underlined] – KILO 1,000
MEG 1,000,000
OHMS LAW.
[underlined] Pressure Increase [/underlined] will equal proportionate current [underlined] increase [/underlined]
[underlined] Resistance Increase [/underlined] will equal proportionate current [underlined] Decrease [/underlined]
[diagram] Voltage is directly proportional to I & R.
[page break]
[underlined] Basic Electricity [/underlined]
[underlined] Matter [/underlined] – Anything that has weight. (ie. Liquids or Gasses.)
[underlined] Molecules [/underlined] – smallest particle of a compound that can exist, and still retain the properties of that compound.
[underlined] Atoms [/underlined] – sub-division of a molecule. [underlined] 92 [/underlined] Atoms known to be in existence – Element.
[diagram]
Atom with no [deleted] [indecipherable word] [/deleted] [inserted] electrons [/inserted] is [underlined] pos. ionised [/underlined]
Atom with 2 electrons is [underlined] neg ionised [/underlined]
[underlined] Free Electrons [/underlined] – Electrons which are free to move from one atom to the other [circled +] [circled +] [circled +]
[underlined] Conductor [/underlined] – A substance with a large number of free electrons.
[underlined] Insulator [/underlined] – Opposite of a conductor.
[underlined] Conduction Current [/underlined] – takes place inside a Conductor.
[underlined] Insulator [/underlined] – [underlined] Displacement current. [/underlined] when potential is applied.
[page break]
[underlined] Basic Theory. [/underlined]
[underlined] Waves [/underlined]
Kinds [underlined] 1. [/underlined] Transverse Waves. [symbols] (ie. Water, Radio).
[underlined] 2. [/underlined] Longitudinal Wave [symbol] (side. View). [symbol]
[underlined] 1. Length. [/underlined] [diagram]
[underlined] 2. Amplitude [/underlined]
[underlined] 3. Speed. [/underlined] 186,000 miles per sec. (Radio).
[underlined] 4. Frequency [/underlined] Greater wave length – Smaller freq.
Smaller “ “ = higher freq.
[formula]
Damped Oscillations. ((i.e. piano string.)
Un-damped “ (i.e. organ note.).
[page break]
Electrical & Radio Pubs.
AP1970 – Standard Notes for W/ops.
AP1186 – All Marconi Fen. (PT 4.) & Everything
AP2548A [symbol] – Gen on TM54 & R1155. complete.
AP.1186A. VHF Equipment
1186B. Radio Aids to Navigation
1186D. Airborne Electrical Equipment.
1186E. Ground “ “
AP2528 TR1143. V.H.F.
AP2535C [symbol] TR1196 complete.
CD0769A Radar principles.
AP2554A Tx “Walter” dinghy effort “Tx3180”
[symbol] Ratcliffe – the Adult Class.
Woodworth – Psychology.
Hughes & Hughes – Learning & Teaching
[page break]
Publications.
SD. Secret Docs. C.D. Confidential Docs. AP. – Air Pubs.
A.M.P. Air Ministry Publications Pamphlets.
A.P. 113 – List of all AP. Air diagram, forms etc.
S.D. 0500A. – Index to signals & radar publications.
C.D. 0500C. Index to American radio & radar publications.
A[deleted]C[/deleted]R1083. RAF sigs manual PT. I.
Outlines the R.A.F. signal organisations & method [underlined] organisations [/underlined] of signalling.
AP3032 [symbol] RAF sigs manual PT. III. Signalling procedures (W/T R/T & visual)
B.C.S.S.I. 1. General 2. Operations 3. Aircraft. 4. Groundstation 5. Tele-communications 6. SD’s & CD’s. 7. Radar
C.C.B.P. 1-5 Combined Communications Board Procedure.
PTS. [underlined] 1. [/underlined] W/T procedure
[underlined 2. [/underlined] Operating signals [deleted] PT.2 [/deleted]
[underlined] 3. [/underlined] R/T procedure
[underlined] 4. [/underlined] Visual procedure.
[underlined] 5. [/underlined] Teleprinter “
CCBP. 0127. Air to Ground Authentication Sigs.
AP3026. – “Q” Code
3 GP SSI’s – Group Standing Signal Instructions.
AMO’s Sect A. Standing Orders.
N Temporary Orders
AP.1762. – Electrical & Radio Notes for W/ops.
AP3023. Theory Notes for Radio Mechs.
AP1093. RAF Sigs Manual PT. 2. (Highly Technical Theory).
[page break]
[blank page]
[page break]
[underlined] T1154. MO. [/underlined]
[underlined] C5 [/underlined] Gives grid bias to grid
[underlined R11 [/underlined] Electrons leak away from grid
[underlined] R3 [/underlined] Cuts down HT input on to anode to 23 ov
[diagram]
[page break]
[underlined] TR1196 Tx PORTION [/underlined]
[underlined] SHOWING LINK UP WITH VALVEs 5 & 6 in THE Rx [/underlined]
[diagram]
[page break]
[underlined] 1. Crystal Oscillator. [/underlined] Valve [underlined] 1 [/underlined] VR 91 PENTODE
One of 4 crystals is selected by the step by step motor in the chassis assembly. The P.A. is fed from this stage via an RF transformer giving a flat response to the whole 4-3 to 6.7 mc/s frequency band.
[underlined 2 Power Amplifier [/underlined] V2. VT50I TETRODE
Four identical tuned circuits, each a continuously variable inductance, with Aerial & Earth as the capacity of the circuit, are the [deleted] output of the [/deleted] output of the set. One of these ccts is selected at each position of the step by step motor.
Resonance while tuning is indicated by a low power lamp in the aerial circuit, which is normally shorted out by a spring plunger.
Since the P.A. tuned circuit also forms the grid circuit of the Rx RF. Amplifier
[page break]
[underlined 2 [/underlined]
it is necessary to tune the Tx before tuning the Rx.
[underlined] Range ‘D’ [/underlined]
The power of the Tx is reduced on this range, to give the necessary Danky range of 10 mls. This is done by inserting an 1800 ohms resistor in the AE circuit of this range.
[underlined] 3 MODULATOR V3 [/underlined] VT52. PENTODE
The Rx output stages V5 & V6 act as Sub-Modulator, and feed modulation frequencies to V3. whose anode load is a [underlined] tapped choke [/underlined]. Voltage variations accross [sic] a.c. due to Auto Transformer action in the choke, and varies the anode & screen voltages of the P.A. valve at modulation frequency.
[page break]
Modulation is the compression of Audio freq waves or radiation waves of radio frequency
[diagram]
[page break]
[deleted] The Tx output ccts are used as input [inserted] H tuned [/inserted] ccts for the Rx.
Power input input in A/C general electrical system
“D” 18 ohm res. [/deleted]
Anode Mod – mod voltages are introduced into the anode cct of the amplifier. Causes the anode voltage on the amplifier to fluctuate at modulation frequency. The audio signal introduced in the anode cct is an alternating voltage which periodically adds & subtracts from the fixed HT voltage. The variation in anode potential thus result in the production of a mod aerial current.
[page break]
A given RF output power is obtainable for less DC. input if the PA values are biased beyond cut off, so that the drive is in the form of sharp “flicks” at positive peaks of the oscillator output [underlined] CLASS “C” Amplification. [/underlined] this also has the merit that when the oscillator is [deleted] working [/deleted] not oscillating the PA draws no anode current.
[page break]
[deleted] Airborne Equip designed primarily for the FAA. R/F & MCW.
Quantity Xstal controlled.
Class C. amp in Tx output stage anode modulated.
The T1134 tuned cct with valve osc. [/deleted]
[underlined] ANODE CHOKE MODULATION [/underlined]
[deleted] (BC.) [/deleted]
[underlined] AF CHOKE [/underlined]
[diagram]
[underlined] Auto-Transformer Action [/underlined]
[diagram]
[page break]
6
[inserted] from [/inserted]
minimised by the use of the Master Oscillator. The M.O. is a low power screened oscillator working into a Power Amplifier, which is the real transmitter.
[diagram]
Crystal Control. – Frequency control may also be obtained by using a quartz crystal. The crystal controlled oscillator has a very stable frequency.
Bearings. – Circular Measure:-
One revolution is equal to 360o
North is regarded as 000o
East = 090o, South = 180o
West = 270o, N.E. = 045o
N.W. = 315o and so on.
[diagram]
A bearing is the direction of one place from another measured in degrees (clockwise) from 000o at N.
(i) Forward Bearing is the angle which the direction A to B makes with the N at A. (Angle [symbol]o in Fig.)
(ii) Back or Reverse Bearing is the angle which the direction B to A makes with the N at B. (Angle [symbol]o in Fig.)
To convert from forward bearing to back bearing, and vice versa, if the bearing is less than 180o ADD 180o. If the bearing is greater than 180o SUBTRACT 180o.
Note:- The direction finding bearing obtained by an aircraft will be a forward bearing.
The Loop Aerial used for direction finding on account of its directional properties. It receives or transmits maximum signal in the direction in which the loop is pointing, and zero signal at right angles to the loop. For aircraft fitted with rotatable loop, tune in and identify a ground station transmitter of good signal strength. Rotate loop until signal is at minimum strength. Read off from the 360o scale attached to loop, the bearing of transmitter relative to the direction of the aircraft. The “sense” of the station can be found by taking a second bearing of the transmitter after a short interval.
[page break]
[inserted] ME Staves. [/inserted]
[underlined] FOR OFFICE USE ONLY. A.M. Pamphlet 115. [/underlined]
ELECTRICAL AND WIRELESS NOTES
Electron is the smallest amount of negative electricity which exists.
Electrical Current is the flow of free electrons in one direction. The symbol for electric current is I. Must have (i) a continuous path, i.e., a complete circuit; (ii) an electric pressure difference (POTENTIAL DIFFERENCE) to force the electrons in one direction.
Conductor. – A substance through which a current can be passed.
Insulator. – A substance which does not conduct a current of electricity.
Quantity of Electricity. – The practical unit is the Coulomb. It is a very large number of electrons.
Unit of Current. – The Ampere which is one Coulomb of electricity passing a given point in one second.
Voltage. – The electric pressure necessary for a current. Is usually called Electromotive Force, or P.D.
Unit of E.M.F. or P.D. is the Volt: Symbol V.
Production of E.M.F. –
(i) Electro-magnetic, e.g., dynamo or generator.
(ii) Chemical, e.g., cell or batteries.
(iii) Thermal – heating a thermo junction.
Resistance is the opposition to the flow of electricity: Symbol R.
Unit of Resistance is the Ohm. Symbol [symbol]
Ohm’s Law. – This law means that if the voltage is changed then the current changes in a like manner, i.e., double the P.D. – double the current; and if the resistance is altered then the current alters inversely; i.e., if resistance is doubled, current is halved.
Shorthand method of writing Ohm’s Law:-
[formula]
Resistances. – (i) In Series. – Combined resistance (R) is sum of separate resistances.
[formula]
(ii) In parallel. – Combined resistance (R) is less than the least resistance of the group.
[formula]
Multiple and Sub Multiple Unit. –
MEG – M =, 1,000,000 times the standard unit: e.g.,
[formula]
KILO – K = 1,000 times the standard unit, e.g.,
[formula]
MILLI – m = 1/1,000 part of the standard unit: e.g.,
[formula]
MICRO – u = 1/1,000,000 part of the standard unit: e.g.,
[formula]
[page break]
2
Instruments. –
(i) Ammeter -
(a) measures size of current.
(b) connected in series in circuit.
(c) has low resistance.
(ii) Voltmeter –
(a) measures size of voltage.
(b) connected in parallel across circuit.
(c) has high resistance.
Uses of Current. –
(1) Heating effect – fuses, electron emission in valves, etc.
(2) Chemical effect – accumulator charging, electro plating, etc.
(3) Magnetic effect – electro magnets, electro magnetic induction, etc.
Cells. –
(1) Primary -
(a) Wet Type – Leclanche cell – liquid electrolyte.
(b) Dry Type – electrolyte – moist paste.
(c) Inert type – electrolyte in form of crystals – needs activating before use.
(2) Secondary or Accumulator –
(a) Lead acid type. – Can be recharged by sending a current through it. Chemical effect of current restores original components and energy is thus stored in accumulator.
Charged State –
Voltage about 2.2 volts in open circuit.
S.G. of electrolyte (sulphuric acid) 1.270.
+ ve plate – brown lead peroxide.
- ve plate – grey spongy lead.
Discharged state –
Voltage falls to 1.8 volts on load.
S.G. of electrolyte falls to 1.15.
Both plates change colour due to formation of lead sulphate.
Capacity of Accumulator – described as Ampere Hours usually based on 10 hr. rate; 90 A.H. at 10 hr. rate means cell ought to give 9 amps. for 10 hrs.
(3) Alkaline Cell – Electrolyte alkaline. Voltage about 1.4 volts when charged, and about 1.1 volts when discharged. S.G. of electrolyte does not vary.
Milne H.T. unit consists of 96 of these cells and can be used to give 120 volts for H.T. purposes.
Magnetic Fields. – The region around a magnet in which magnetic forces act or can be detected is called the Magnetic Field. Conductors in which currents are maintained behave like magnets, and possess a magnetic field. The magnetic field due to a coil or Solenoid carrying a current is similar to that of a bar magnet. Lines of Force indicate the directions in which these magnetic forces act. An iron core inserted in a solenoid causes the magnetic forces to become much stronger: e.g., an electro magnet.
[page break]
3
D.C. Motor. – Changes electrical energy into mechanical energy. A coil of wire, mounted on a shaft, and carrying a current of electricity, is placed in a magnetic field. The result of superimposing these two magnetic fields (i.e. a magnetic field of coil and the one supplied) is the development of a force which tends to rotate the coil. In an electric motor a number of coils are used. As these rotate the current is sent through each coil by means of a commutator, which is connected to the external supply by means of brushes.
Induced E.M.F. – Whenever the Magnetic Flux threading a circuit changes an E.M.F. is induced in the circuit. The size of this induced E.M.F. depends upon the speed at which the flux changes i.e., the greater the speed of changing flux, the greater is the induced E.M.F. (Faradays Law).
D.C. Generator. – changes mechanical energy into electrical energy. A continual change of flux is produced by rotating a coil of wire in a magnetic field, so inducing and maintaining an induced E.M.F. in the coil. An alteration in the speed of rotation or the flux, or both, produces an alteration in the maximum value of the E.M.F. induced. This E.M.F. so produced is an alternating E.M.F., and to obtain a direct E.M.F. a commutator must be used.
Back E.M.F. – The E.M.F. induced in the coils as they rotate in the magnetic field. It acts in opposition to the applied voltage in the case of the electric motor.
The Motor Generator (M.G.). – this is an electrical motor driving a generator. The armature windings for each machine are wound on the same armature, but are insulated from each other. Type E Motor Generator is employed in the aircraft for the H.T. supply to the radio transmitter. Each armature winding has its own commutator and brush gear.
Type 49 Switch. – Tumbler switch and resistance for starting the M.G. – has three positions OFF – START – RUN.
Type “A” Starter. – For remote control in starting the M.G. and automatically cuts out starting resistance when motor has gained speed.
Radio Communication. – Requirements – Transmitter to transmit a signal; a Medium to convey the signal; a Receiver to receive the transmitted signal.
Alternating Voltage or Current, is one which continually varies in size and direction.
Cycle is one complete sequence of variations.
Amplitude is the maximum value of the alternating quantity in a cycle.
Frequency is the number of cycles per second. Symbol (f).
Frequency Ranges. –
(i) Audio Frequencies (a.f.) between 50 cycles per second and 10,000 c/s.
(ii) Radio Frequencies (r.f.) between 10,000 c/s and 50,000,000 c/s.
Wavelength is the distance traversed by 1 cycle. Symbol [symbol]
Inductance. – the property of a coil of wire to oppose current changes. Symbol L. Unit of Inductance is the Henry. Smaller unit is the micro-henry ([symbol]H). A larger number of turns of wire and a soft iron core increases the inductance.
Condenser. – Consists of two conductors, very often metal plates, separated by an insulating medium such as air, mica, waxed paper oil, etc.
[page break]
4
Capacity. – The ability of a condenser to acquire a charge of electricity. Symbol C. Unit of Capacity is the Farad. Smaller unit is the microfarad ([symbol]F).
Simple Oscillatory Circuit consists of essentially of a condenser (to give capacity) connected across an inductive coil. When the condenser is discharged through the coil, an alternating current of numerous cycles per second is set up, provided the resistance is not too high. Such a current which surges to and fro many times a second is called an Oscillatory Current and the circuit an Oscillatory Circuit.
Frequency of Oscillations is given by [formula]
Note that if L or C is increased f is decreased, and vice versa.
Damping. Is the “dying away” of these oscillations, due to resistance.
Open Oscillatory Circuit is simple oscillatory circuit “opened out” i.e., aerial and earth acting as the plates of the condenser. The circuit then emits wireless waves and is the basis of the simple transmitter.
Tuning means the alteration of L or C (by adjusting the inductance or condenser) so that the natural frequency of the tuned circuit is that of the incoming signal. The circuit is then said to be in Resonance.
Selectivity. – The ability to respond to a selected signal and reject unwanted signals.
The Thermionic Valve. –
(i) Diode consists of Filament and a plate or Anode in evacuated glass bulb. The filament is heated by L.T. battery and emits electrons which are attracted to the Anode when it is made positive with respect to the filament, by connecting it to the H.T. supply. This is called the anode current.
(ii) Triode. – Similar to Diode but has a mesh of wire or spiral called the Grid between the filament and anode. By varying the grid potential with respect to the filament, the anode current can be controlled and varied.
Uses of Valve. –
(1) As a Sustainer of Oscillations. – By means of “feeding back” energy from the output of the anode circuit to the grid circuit, the oscillations will be maintained at a steady amplitude and will not be damped. The valve is then acting as an oscillator.
(2) As a Detector or Rectifier. – When an alternating voltage is applied, the valve allows impulses to flow in one direction. This means of obtaining a direct current from an alternating current is called Rectification.
(3) As an Amplifier. – Enables a magnified alternating voltage to be passed on to the next stage. This is done by passing the fluctuating anode current through a load (a resistance, choke, etc.) which sets up an amplified voltage across it. (V = I x R).
Types of R.F. Signals.
(i) Continuous Wave (C.W.). – Continuous train of waves of constant frequency and amplitude, used for Morse signals, and received by use of heterodyne method.
[page break]
5
(ii) Interrupted Continuous Wave (I.C.W.). – Interrupted train of waves of constant frequency, by means of “tone” wheel, used for Morse signals and can be received by ordinary receiver.
(iii) Modulated Wave (R.T.) is a signal of constant frequency but the amplitude varies at audio frequency.
Modulation. – the impression of audio frequency variations (e.g., speech) on radiation waves of radio frequency.
The Carbon Microphone consists essentially of thin metal plate which lightly rests on carbon granules. Sound waves cause diaphragm to vibrate, thus carrying the packing of the carbon granules and so altering the resistance of the circuit. The current in the circuit will fluctuate at A.F.
The Telephone Receiver. – This is really an electromagnet together with a thin iron diaphragm, which can only respond to A.F. When A.F. currents pass through the windings of the electromagnets, the fluctuations in current cause the diaphragm to vibrate, and so reproduce the sounds which were originally made at the microphone.
Rectification or Detection. – The separation of the A.F. from the R.F. of the signal at the receiver end, in order that the telephone may respond to the A.F. current. The valve does this unravelling when used as a detector.
Heterodyne. – C.W. Reception. –The incoming signal is combined with an alternating voltage the frequency of which is slightly different from that of the incoming signal, and which is supplied by a local oscillator in the receiver. These two voltages will alternately get in and out of step. The amplitude of the combined voltage will thus vary at BEAT, or DIFFERENCE, FREQUENCY, and when detected the pulses will operate telephones in the anode circuit.
Screen Grid Valve. – An extra wire mesh is placed between the anode and grid in such a way that it prevents undesirable oscillations due to the internal anode-grid capacity of the valve.
Block Schematic Diagram of Straight Receiver.
[diagram]
T.C. – Tuned circuit used to “tune to” or “select” the required signal.
R.F. Amplifier Stage is valve circuit to magnify the incoming signal voltage.
Detector Stage is valve circuit to obtain the a.f. voltage from the R.F. signal.
A.F. Amplifier Stage is valve circuit to increase the A.F. voltage from detector circuit in order to operate telephone.
The Master Oscillator (M.O.). – Swaying aerials, mechanical vibration, temperature changes, etc., may cause variations in the frequency of a signal radiated from a simple transmitter. These frequency variations are
[page break]
6
[inserted] from [/inserted]
minimised by the use of the Master Oscillator. This M.O. is a low power screened oscillator working into a Power Amplifier, which is the real transmitter.
[diagram]
Crystal Control. – Frequency control may also be obtained by using a quartz crystal. The crystal controlled oscillator has a very stable frequency.
Bearings. – Circular Measure:-
One revolution is equal to 360o
North is regarded as 000o.
East = 090o, South = 180o.
West = 270o, N.E. = 045o.
N.W. = 315o and so on.
[diagram]
A bearing is the direction of one place from another measured in degrees (clockwise) from 000o at N.
(i) Forward Bearing is the angle which the direction A to B makes with the N at A (Angle 0o in Fig.)
(ii) Back or Reverse Bearing is the angle which the direction B to A makes with the N at B. (Angle [symbol]o in Fig.)
To convert from forward bearing to back bearing, and vice versa, if the bearing is less than 180o ADD 180o. If the bearing is greater than 180o SUBTRACT 180O.
Note. – The direction finding bearing obtained by an aircraft will be a forward bearing.
The Loop Aerial used for direction finding on account of its directional properties. It receives or transmits maximum signal in the direction in which the loop is pointing, and zero signal at right angles to the loop. For aircraft fitted with rotatable loop, tune in and identify a ground station transmitter of good signal strength. Rotate loop until signal is at minimum strength. Read off from the 360o scale attached to loop, the bearing of transmitter relative to the direction of the aircraft. The “sense” of the station can be found by taking a second bearing of the transmitter after a short interval.
[page break]
[underlined] 2 [/underlined]
[underlined] A1134A [/underlined]
[deleted] Howe [/deleted] How [underlined] used [/underlined]
[deleted] [underlined] USES a [/deleted] [inserted] as [/inserted] [underlined] AS i/c Amplifier. [/underlined]
[underlined] 1 [/underlined] Crews mikes are always connected to [underlined] INPUT [/underlined] & phones to [underlined] OUTPUT [/underlined]
[underlined] 2 [/underlined] W/ops phones & mike connected to to [sic] i/c system on [underlined] B [/underlined] & [underlined] C [/underlined] pos [underlined] only. [/underlined]
[underlined] AS. OUTPUT AMPLIFIER [/underlined]
[underlined 1 Amplifiers TR1196 Rx output [/underlined] in [underlined] all [/underlined] pos of ABC switch
[underlined] 2 [/underlined] Amplifiers R1155 output for [underlined] whole [/underlined] crew on “C” pos. of ABC switch.
[underlined] NB [/underlined] [deleted] 3 [/deleted] [underlined] NO [/underlined] amplification of R1155 for Wop in A & B pos.
[underlined] AS SUB-MODULATOR [/underlined]
Works [underlined] ONLY [/underlined] on [underlined] “C” [/underlined] position & all [deleted] [indecipherable word] [/deleted] mikes can modulate [underlined] T1154. [/underlined]
[page break]
[circled 4]
[underlined] Conclusion [/underlined]
Questions Etc
[deleted] Q.P.P. [/deleted]
(Input circuits designed to [inserted] give [/inserted] low magnification at freq below 500 cps cut down engine noise)
(Sub-mod.) due to much smaller output obtained from EM. mikes than from C. Output of A1134A is fed to Mod valve of [underlined] T1154. [/underlined]
[page break]
[underlined] 1 [/underlined]
[underlined] A1134A [/underlined]
[underlined] INTRODUCTION [/underlined] A most important piece of Equipment in an A/C. [inserted] provides i/c in A/C. [/inserted] (conversant). (over the [underlined] [deleted] Aerial [/deleted] Details [/underlined], its [underlined] uses [/underlined] and the [underlined] I/C Faults. [/underlined] A detailed description of the circuit will be given you in a later lecture.
A battery operated 2 Stage [underlined] AF Amplifier [/underlined] & is used with Electro-Magnetic mikes. There are 2 Valves in the set – 1 is ([underlined] Q to class [/underlined]). [underlined] VR21 TRIODE [/underlined] [inserted] (voltage amp.) [/inserted] and the other (Q to class). [underlined] VR 35 DOUBLE PENTODE [/underlined] Q.P.P. which gives [underlined] High Power Amplification. [/underlined] (no H.T. current until speech freq are [indecipherable word] economy to HT)
[underlined] POWER SUPPLIES: [/underlined] – 2v ACC. 120V HT BATT
6V GRID BIAS (6v to 35. 3v to 21)
[underlined] Weight 4 1/2 lbs. [/underlined] without Batteries.
[underlined] FUNCTIONS 1. “Q” I/C AMPLIFIER
2 “Q” OUTPUT AMPLIFIER [/underlined] FOR THE 1196 Rx [/underlined] & [underlined] R1155 [/underlined] ON “C” position of ABC [underlined] switch [/underlined]
[underlined] 3 “Q” SUB-MODULATOR [/underlined] FOR [underlined] T1154 [/underlined] on [underlined] “C” [/underlined] pos of ABC switch/.
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[underlined] 3 [/underlined]
[underlined] A.B.C. SWITCH. [/underlined]
W/OP
I/C – TR1196 – T1154/55
[underlined] A.[/underlined] YES – - – -
[underlined] B. [/underlined] YES – YES – YES
[underlined] C. [/underlined] YES – YES – YES
CREW.
I/C – TR1196 – T1154/55
[underlined] A. [/underlined] YES – YES – -
[underlined] B. [/underlined] YES – YES – -
[underlined] C. [/underlined] YES – YES – YES
[underlined] FAULTS. FAULT CAUSE REMEDY [/underlined]
[inserted] [underlined] Q.’s [/underlined] [/inserted]
(Feed back between phones & mikes circuits)
[inserted] [underlined] LOW H. [/underlined] [/inserted] [underlined] 1. [/underlined] Dampness in i/c sockets or in headset.
[inserted] [underlined] LOW H. [/underlined] [/inserted] [underlined] 2. [/underlined] Defective screening & bonding in headset on A/C wiring. (ie broken mike lead)
[deleted] [indecipherable word] [/deleted]
[inserted] [underlined] LH [/underlined] [/inserted] [underlined] 3. [/underlined] Run down Power Supplies.
[underlined] 4. [/underlined] Defective valves. ([underlined] High Prowl [/underlined])
[underlined] 5. [/underlined] Intermittent i/c – Loose plugs, (1.3.5.7. slip rings on M/V turret.).
[underlined] NO Joy [/underlined] Clean A/CC spade leads.
[underlined] IF U/S. [/underlined] N/E switch on [underlined] 192 [/underlined] panel. Switch off A1134A. Using the AF stages of the 1196 Rx as i/c amplifier.
(3 to 5 pairs of phones)
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IDH [inserted] [underlined] valve [/underlined] [/inserted] can have a fluctuating supply to the heater but it will not affect the cathode
[diagram]
[deleted] Series feed because current to the anode from the HT supply passes through the osc. Circuit. [/deleted]
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[underlined] Keying [/underlined]
Key up. [inserted] large [/inserted] neg v to grids of MO. PAs)
Value of RG. 5000 [symbol]
45 m/a. passing through R9.
[underlined] 225v [/underlined] dropped accross [sic] R9.
[deleted] Supp Grids control output power of Tx vary output power vary I through PA’S (40v – [inserted] [deleted] [circled R10] [/inserted] [/deleted] [inserted] [circled R10] [/inserted] on Supp Grids when key is pressed on Tone)
CW S Grids [inserted] 30v [/inserted] + from R8 [/deleted]
[deleted] [underlined] C5 [/underlined] Grid Bias to Grid
[underlined] R11 [/underlined] E leak away from Grid
[underlined] R3 [/underlined] cuts down v to 230v to anode [drawing] [/deleted]
[deleted] Preset Anode Tempo [underlined] Red Range only [/underlined] do diagram [/deleted]
[deleted] R4 20000 [symbol]
R7 12,000 [symbol]
R10 350 [symbol]
R8 2000 [symbol]
R9 5000 [symbol]
R12 20000 [symbol] [/deleted]
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[underlined] 1 [/underlined]
[underlined] T1154. MO. [/underlined]
[underlined] INTROD. [/underlined] WE HAVE ALREADY GONE THROUGH THE VARIOUS STAGES OF THE Tx SO NO I INTEND TO HAVE A REVISION OF THE MO STAGE.
IN THE BUILDING UP OF OUR Tx WE FOUND THAT TO DETERMINE THE FREQ OF OUR MO CCT. WE MUST [underlined] HAVE A Q [/underlined] TUNED CIRCUIT [diagram] WE WANT TO MAKE THIS CCT SO THAT WE CAN TxMIT ON ANY FREQ SO [underlined] Q HOW CaN WE VARY THE FREQ IN THIS CCT? [underlined] ANS [/underlined] By [underlined] VARYING [/underlined] THE [underlined] L OR CAPACITY. [/underlined] IN THIS CASE WE USE A [underlined] ‘VARIABLE CONDENSER’ [/underlined] SUPPOSING THE CONDENSER IS ALREADY CHARGED WE CAN NOW GET I FLOWING ROUND THE CCT & CAUSING IT TO OSCILLATE. BUT DUE TO RES ETC. IN THE CCT THESE OSC DIE AWAY AND
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The MO valve has its tuned cct connected between [underlined] grid & anode [/underlined] & the HT supply is fed through a tapping point on the coil. [deleted] Condensor [sic] [/deleted] Connection to Earth via condenser. “Series fed H. use cct.”
[underlined] 1. [/underlined] When the Tx is osc. the MO valve receives automatic bias from the grid leak & condenser combination C5 R11 the res R9 being short cctd & the grid leak keyed to earth via the keying relay contacts
[underlined] 2 [/underlined] When the Tx master switch is on Tune & Key Up & [inserted] the keying contacts are open. [/inserted] the flow of HT current through R9. renders the control grid of the MO PA. valves negative with respect to their cathodes & no osc takes place. When the key is down the relay contacts close short cctg R9 so that leak is removed from the control grids & the cct oscillates.
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[underlined] 3 [/underlined] Grid leak & Condensor [sic] put into cct
[diagram]
[underlined] Disadvantage of others [/underlined] gives a large anode current & [symbol] we want to cut it down.
[underlined] ie [/underlined]
[diagram]
[underlined] Q [/underlined] How do we cut Anode current down?
[underlined] A [/underlined] By using grid Bias. & the means we use is by putting a condensor [sic] and a grid leak between the [underlined] grid [/underlined] & [underlined] filament [/underlined].
We employ a – bias on the grid so that the grid just
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