Examples of Alan Dower Blumlein's handwriting

1) AD Blumlein to Columbia Graphaphone Company - 13 September 1931: 

From A.D. Blumlein

67 Earls Court Sq.

S.W.5.

13th Sept 1931

J. Gray Esq.

Columbia Graphophone Co. Ltd.

Dear Sir,

I am writing to you to thank the company for the bonus which I have just received in connection with the new recording system. I appreciate that that [sic] the face value of the bonus is considerably enhanced by the depressed times in which it is made, and I am therefore very grateful for it.

May I also thank the Company for having given bonuses to Messrs. Holman and Clark, whose very good work, I was rather afraid was not fully appreciated. My fears on this score I find unfounded.

Thanking you Sir,

Yours faithfully

2) AD Blumlein notes to self - Saturday, 6 June 1942

The example above is actually page three of four pages written by Alan Blumlein on Friday, 5 June, Saturday, 6 June and Sunday, 7 June 1942.

These notes are particularly poignant as it very probably was the last thing that Alan Blumlein ever wrote. Eric White, Felix Trott and Maurice Harker had found accommodation at the Swan Hotel in Tewkesbury, just five or six miles up the road from the airfield at Defford. It was decided that Blumlein, Browne and Blythen would drive from Hayes to Defford in an EMI company car (for which EMI petrol rations had been allocated specifically for such purposes), to join them there, on the Friday morning, 5 June 1942. That Friday evening everybody ate dinner at the Swan Hotel and then all went for a walk as Maurice Harker recalled:

“I was walking with C. O. Browne and F. R. Trott, with Blumlein and White a way off ahead of us. Well, after a while of this, it was a lovely summer’s evening you see and not a bit dark yet, C. O. Browne says ‘I’ve had enough of this’, and he’d been walking with some stick or something, so, he proceeded to tap this stick on the ground to get White and Blumlein’s attention or I think they would have walked another five miles, they were that engrossed in conversation. Anyhow, we returned to the Swan, and turned in for the night, and in the morning, I left to return to Pinner and my parents’ house, while they were setting off to the airfield at Defford, and of course that’s the last time I saw Blumlein.”

During the evening of Saturday, 6 June 1942, V9977 did make one final check flight before the designated full test the next morning. On board were Geoffrey Hensby and Bernard Lovell and both noticed the magnetron system responding to echoes of towns and features at a far greater distance than had previously been reported. With everyone returning quite late in the to the hotel in Tewkesbury. Felix Trott recalled that despite the day’s work, there were still several pre-flight preparatory checks to be completed the following day before the aircraft could take off, but they did not expect these to take long at that time. During Friday, after he had arrived at the airfield and been shown around V9977, Blumlein began to make some sketchy notes (which were probably meant as mere reminders to himself for when he had returned to Hayes), and continued to do so for the rest of the weekend. These hand-written notes concerning the tests to be carried out still survive in the vast EMI archives, and written in pencil on four pages which have been torn out of standard memo pad, and dated 5 June, 6 June and 7 June 1942, they give us a quite unique insight into the thoughts of Alan Blumlein as the EMI team prepared for the tests that lay ahead that weekend. The four pages have been transcribed as follows (The text is often cryptic and the spelling Blumlein’s):

 

(Page One)

O’Kane & Selves, Sq/Ldr Samson. 5th June 1942.

1) Motor Control. a) Motor comes up automatically when H.T. button pressed. b) Two pole switch on power unit to stop scanner. c) Lead to Motor 6B. Scramet. Puis ou rockets // 3 by 3.

2) Marker Control. To be switch not key. Marker is essential if RD confirms control fitted.

3) Control Box Shape. As shallow as possible — e.g. to fit 5” tray. Box for control on R.H. and W. plugs on L.H. Spikes & catches top and bottom. Presets (Height Zero, Range Zero, Brightness) on RH Side above (or below) boss if this can be arranged.

4) Scan & Range Marker Controls. Delete one switch and gaug. Decision on range to follow flights.

5) Indicating Angle Marking. Make as planned with thumb moved drift plate with degrees red against a vumb line at bottom. Plate to have 3 parallel lines plus 10° (920°) lines at either side forward see text opposite. Agreed.

6) Push About. It looks as though large push about not necessary but three ranges required and adjustable centring. This is not a decision but depends on flight trials.

(Page Two)

7) Subject to confirming test at Hayes, we fit transformer instead of lead amplifier.

8) Make up all units on basis of flight trials set as now modified at Hayes.

9) Decide use 2A plugs W196 for destructor.

10) Will decide out of hand at Hayes whether 18 or 12 for A.S.V.

11) Decided tests should be made with test equipment to allow orders to be placed

 

(Page Three)

6th June 1942. Dee, Lovell, O’Kane, Samson & Selves.

1) Scan Rotation. Stayed at 60 or 20, not to be increased to want higher repetition.

2) Want additional display unit. Won’t provide unless amplify incorporated to tee off existing arrangement so makes no difference.

3) N Seeking is a good thing, the line of flight maybe definitely rgd.

4) We will attempt to move plugs from R.H. to L.H.

5) Lovell thinks the meter for crystal circuit is a stupid idea.

6) Marker & Scan rages, Provisionally

Scan Range                     Marker Range associated

10                                          10 on correcting & renn.

30                                          50 linear

50-100                                100 rule (got by above x 2)

7) Agreed no push about but centring useless.

8) Screen as 5) of 5th June. Note ground speed lines unpredictable due to slant range distortion and errors of scan amplitude.

9) TRE to let us know experience on blowing & mounting

10) Destructors small straight two pin

11) (Originally written: “TRE want 1st I.F. must be in T2R not on because Mk. VIII has got it & designs have been based to get Gram Co...”, there Blumlein must have changed his mind as the entire passage is heavily crossed out and he re-wrote the following) T.R.E. will discuss advisability of having 1st I.F. in T2R.

12) Discussed use of new power Klystron, decided to carry on with existing modulator.

 

(Page Four)

Note. Warn Oura jack may be required on T2R.

13) Interrogator. Conference to be arranged to re-hash.

14) Motor on 6 pin shoe & stop switch

15) 12 & 18 way decision out of hand at Hayes

16) Go ahead to make prototypes.

17) EMI to provide mock ups of all units mid T2R & M

7th June 1942.

We Form Monitor. Mk. VIII type or Test set 31. (TRE to produce Mk. VIII type for discussion)

I.F. Signal Generator. (To be produced by us for 1st Tests only)

Wavemeter

Signal Generator R.F.

Field Strength Measurer.

 

There the notes end.

The notes for the 7 June were most probably made during the morning at Defford, and therefore the last writing he ever made.

Here is a breakdown of what each item on each page probably meant: 

Technical Summary – Radar Development Meeting

Dates:6–7 June 1942
Attendees:Dee, Lovell, O’Kane, Samson, Selves
Location:Hayes / TRE

1. Motor Control

• Motor to start automatically when H.T. (high tension) button is pressed.

• Two-pole switch provided on power unit to stop scanner.

• Motor lead to be wired to terminal 6B.

2. Marker Control

• Marker to be controlled by a switch, not a key.

• Marker is essential if Radio Direction (RD) confirms control fitted.

3. Control Box Design

• Box to be as shallow as possible (e.g., to fit into 5-inch tray).

• Control knobs on right-hand side, wiring plugs on left-hand side.

• Spikes and catches on both top and bottom of the unit.

• Preset controls (Height Zero, Range Zero, Brightness) to be positioned on the right-hand side above (or below) boss if possible.

4. Scan & Range Marker Controls

• One switch and one gauge to be deleted.

• Final decision on range settings to follow results from flight trials.

5. Angle Indication

• Angle marking to use thumb-operated drift plate with degree scale in red against a fixed line at the bottom.

• Plate to include three parallel lines plus ±10° reference lines.

• Design agreed.

6. “Push About” Controls

• Large push-about control not required.

• However, three ranges must be provided with adjustable centering.

• Final decision pending flight trial results.

7. Amplifier vs Transformer

• Subject to test at Hayes: replace lead amplifier with transformer.

8. Basis for Construction

• All units to be constructed according to the configuration established during flight trials at Hayes.

9. Connectors

• Use of 2A plugs (W196 type) for destructor circuits under consideration.

10. ASV Connector Decision

• Hayes to determine whether 12-way or 18-way connector is most suitable for ASV equipment.

11. Test Equipment

• Dedicated test equipment to be built in order to permit firm orders to be placed.

12. Scan Rotation

• Maintain at 60 or 20 (do not increase). This provides adequate repetition.

13. Display Unit

• Additional display unit requested.

• Only feasible if amplifier is added to tap existing signal without degradation.

14. N-Seeking

• North-seeking facility considered useful.

15. Plug Rearrangement

• Move plugs from right-hand side to left-hand side where possible.

16. Crystal Circuit

• Lovell strongly opposed to fitting a meter for the crystal circuit.

17. Range/Marker Settings (Provisional) Scan RangeMarker Range10/10 (correcting) 30/50 (linear) 50–100/100 (scaled by ×2)

18. Screen

• Screen to follow 5th June design.

• Ground speed lines unreliable due to slant range distortion and scan amplitude errors.

19. TRE Experience

• TRE to provide feedback on blowing and mounting issues (cooling/structural).

20. Destructors

• Use small straight 2-pin connectors.

21. IF Stage (T2R Unit)

• Original proposal to place 1st I.F. inside T2R crossed out.

• Revised decision: TRE to discuss advisability of placing 1st I.F. in T2R.

22. Klystron

• Decision taken to continue with existing modulator.

• Do not adopt new power klystron at present.

23. Interrogator

• Separate conference to be arranged to review interrogator requirements.

24. Motor Connections

• Motor to use 6-pin shoe with stop switch.

25. Prototype Production

• Go ahead authorised for prototype builds.

• EMI to provide mock-ups of all units (mid-T2R and “M”).

26. Test Equipment (7th June 1942)

• Monitor set (Mk. VIII type or Test Set 31 – TRE to supply Mk. VIII version).

• I.F. Signal Generator (for initial tests only).

• Wavemeter.

• R.F. Signal Generator.

• Field Strength Meter.

Summary

The June 6–7 1942 meetings finalised design directions for the ASV radar and T2R unit, covering motor controls, range/marker settings, connector standards, and control box layout. Hayes trials remain the reference point for practical decisions. Prototypes are to proceed immediately, with EMI providing mock-ups and TRE supplying test equipment.