* Here  it  is !

the   NEW RECEIVER   


Here after many rumours and much waiting

As the early years of the war progressed the shortage of radio receivers in Britain began to take its toll. Government communications to the public were vital to the national war effort and keeping up morale. With an estimated up to one million receivers out of service due to the lack of parts or service personnel to repair them, something clearly needed to be done. With British manufacturers now concentrating all their efforts on producing military equipment, the domestic market needed to be helped. The initial measure was for the importation of foreign sets, with some hundred thousand small to medium sized radio receivers coming from American manufacturers, being ordered by the Board of Trade. However, the Government soon realised that this situation could not continue with the problems of Atlantic convoys being increasingly under threat, so looked for other ways to increase supply. So in 1943, the Government was to authorise, via the Board of Trade, the Radio Manufacturers Association (R.M.A) to set up a technical committee to design a standard receiver – that was simple in design; requiring the minimum of components used but still would retain a satisfactory performance and a high standard of reliability. The result was the announcement in 1944 of the “Civilian Wartime Receiver”, with two versions being manufactured, an AC mains version and a battery one being powered by large glass accumulators. Being produced by 44 participating UK manufacturers, although research and my own collection would suggest not all of the participating manufacturers did finally make them. As this was a joint manufacturing adventure, no manufacturing names were placed on the receiver, but each was allocated a code number commencing with the letter U. The U numbers were known only to the wireless trade, to aid warranty repairs and claims. An example being – U7, which was the code for the Murphy company and U1, being for Bush. Full manufacturer’s codes are listed later.


Civilian Wartime Receiver – Specification and Design

The technical design committee of the R.M.A were to come up with what was an almost standard four valve “superhet” for the battery receiver and a three valve (+ HT rectifier) AC mains version. The circuit of the AC mains version was to be quite different to most of the thinking at that time – with the use of a “Westector” metal rectifier for detection. Wartime valve production restrictions at that time also meant that there were no suitable comparable detection valves being produced for military purposes and the Board of Trade would not permit the manufacturer of one purely for the wartime receiver. The design was to be a Medium Wave only receiver with no additional Short Wave or Long Wave circuitry added. The reduction of such items as wave change switches, additional coils etc; aiding the reliability and reduction of unnecessary components. Also, with the BBC at the outset of the war, closing down single use transmitters, such as Droitwich, in an attempt to stop the BBC transmitters being used as direction finding aids by enemy planes, the addition of Long Wave was unnecessary. Further economy and reliability being achieved by the mains set using a resistance / capacity filter for smoothing and a permanent magnet speaker for its output.                                      

The AC Mains Set and its performance specification

 (i) Sensitivity – this should be no less than 325 µV at 220 metres and 625 µV at 500 metres - where output is measured at the speech coil terminals, 50mW.

(ii) Selectivity – the band width should not exceed 11 kc/s (11 khz) at 50% response & 21 kc/s (21 khz) at 10% response.

(iii) Overall Response – this should not be more than 7 decibels down at 100 cycles (100 Hz) or 9 decibels down at 4,000 cycles (4 khz). These cycles are with respect to the level at 400 cycles (400 hz) this response is measured on a resistive output load, and using an R.F input of 10mV, with the aerial terminal A1 modulation applied at 30% and the volume control adjusted to an output of 50 mW at 400 cycles (400 hz).

(iv) A.V.C Threshold – This should be delayed so that it commences to operate when the output is approximately 1 watt on a signal with a modulation depth of 50%

(v) I.F Rejection Ratio – This ratio at no point should be worse than 5 to 1.

The AC Mains set’s specification performance differs to that of the Battery Set in a number of ways. The main differences are listed here below.

The Battery Set and its performance specification

 (i) Sensitivity - this should be no less than 300 µV at 220 metres and 600 µV at 500 metres - where output is measured at the speech coil terminals, 50mW (H.T 120 volts).

(ii) Overall Response – this should not be more than 10 decibels down at 100 cycles (100 hz) or 14 decibels down at 3,000 (3 khz) cycles. These cycles are with respect to the level at 400 cycles (400 hz) this response is measured on a resistive output load, and using an R.F. input of 10mV, with the aerial terminal A1 modulation and the volume control adjusted to an output of 50 mW at 400 cycles (400 hz).

(iii) The oscillator Section of the frequency charger must continue to operate when the set is fed from a 60 volt H.T battery with 2,200 ohms in series.

Circuit of the AC Mains Receiver 

Circuit of the Battery Receiver

The Appearance of the Receiver

The appearance of the receivers, to be made by all 44 manufacturers, had to be as much as possible the same. This included a standard metal chassis, with pre drilled cut outs, for use by both the mains and battery versions and a simple string driven slow motion tuning scale comprising of two metal plates, one fixed and one moving, fitted flush against the cabinet to avoid the necessity of a glass dial.

 A ‘blueprint’ of the cabinet’s appearance was drawn and prepared by the British Radio Cabinet Makers’ Association (Eden Minns the designer) and a subsequent sample cabinet was kept at the R.M.A offices for reference.


The AC Mains Receiver

Pictures taken from the “Murphy News” magazine press release of June 1944

The Battery Receiver

Pictures taken from the “Murphy News” magazine press release of June 1944

Valves and their Manufacturer

Similarly to the U numbers used to identify the manufacturer of a set, the British Valve Association (BVA) allotted codes to the valves which hid the particular manufacturer to the general public. A typical set of valves in an AC mains receiver would be something like BVA274 (f/changer), BVA243 (if amp), BVA264 (output) and BVA211 (rectifier). The last digit of these codes indicates the valve manufacturer e.g.1 being Cossor. It is also worth noting that as far as I have found, not all the valves listed on some Civilian Wartime receiver documentation were actually produced, BVA273 & 277 listed for V1 being two such valves but I may stand corrected!

 BVA Number                                                         Common Equivalent

Ac Model

V1        274 / 275 / 276                                       ECH35

V2        243 / 246 / 247                                       EF39

V3        264 / 265 / 266 / 267                          EL33

V4        211 / 214 /215 / 216                           UU5

Battery Model

 V1       172                                                                 TP25

 V2       142                                                                 VP23

 V3       132                                                                 HL23DD

 V4       162                                                                 PEN25  

 

BVA Valve Code – Final Code Figure Indicates Manufacturer

1:  Cossor   2: Ediswan (Mazda)  3: Ferranti   4: GEC   5: Marconiphone   6: Mullard   7: Standard Telephone (Brimar)

General Quality

As previously stated, one of the main objectives of the original design was reliability and with so many manufacturers producing sets, quality of workmanship etc, could not be guaranteed but the R.M.A were at pains to draw the attention of the manufacturers to the fact that defective apparatus could be traced back to its source, and therefore urged them to adhere to the “spirit” of the specification. Both pricing and condition of supply were also rigidly set by the Wireless Receiving Sets (Control of Supply) order, which came into effect on 1st July 1944. This order was not revoked until July 1947, so one would presume that the civilian wartime receiver was still in production until that time. The retail cost of the A.C. mains model was £12-3-4 (inc. purchase tax) and the battery model was £10-19-0 (inc. purchase tax, but excluding the batteries). Each of the receivers was given a three month manufacturer’s warranty from time of purchase.

Civilian Wartime Receiver Manufacturers Codes used

 

The Peoples Thoughts

I think it must be fair to say that the Civilian Wartime receiver was not that well received, particularly from its timing and partially from it being viewed by many (including some dealers as well) as another piece of “Utility” furniture and basic in its features. Being launched very shortly after D-Day must have had a serious impact on sales with many people thinking that the war in Europe was nearly over and better times (and things!) lay ahead.

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