The Wartime Civilian Receiver

The Wartime Civilian Receiver, popularly known as the ``utility'' set (in keeping with the name other wartime lines of utility goods such as furniture and clothes), was intended to be produced as a functional item, with few frills. As a result it was hoped to maximise production efficiency and avoid detracting from the war effort. Radio equipment for military use had already played a prominent role in the armed forces and manufacturers of domestic radios had in the main turned their production focus to equipment for these armed forces users (such as aircraft radios). The combination of an understanding of the importance of keeping the public informed of the latest news (in contrast with cinema newsreels) and a shortage of domestic receivers persuaded the Radio Manufacturers' Association (RMA) to come up with a standardised Government Approved design. The design was the work of Dr. R. G. Reynolds of Murphy Radio. All manufacturers were to produce a set which was functionally the same (to avoid competition on account of features, and to allow for economy through parts reuse).

The set was produced in two versions, for Mains or Battery power. Fortunately the example at the Museum is a mains version. The Battery version would have used a large glass LT accumulator and HT batteries, with limited life, and which became unavailable after about 1950.

It does the designer tribute that such sets are still around and working today fifty years later. The solid utilitarian design certainly helped, many of them moving out of the house to barns and childrens' bedrooms in the post-war years. An example recently turned up, thickly coated in white paint! Plant pot rings on the top of the case are apparently the most common damage.

Looking at the set it is easy to imagine the primitiveness of pre-war radio sets, that is in fact not the case as some of the early Pye examples at the museum show. Features which the buyer had come to expect in receivers from the pre-war era had to be left out to conserve materials. One such feature was the band change switch; early band change switches made up of multiple paxolin wafers with silver plated contacts, and were both expensive and unavailable since they were required for other war effort applications, so the decision was taken to make the set cover a single band, the Medium Wave Band (MW) where the BBC's programmes could be received at that time. An interesting fact which also may have affected this decision is that at the time, the BBC were doubling up its transmissions onto the same frequencies in geographically separated areas to try and make Direction Finding (and hence bombing) based on using the BBC's transmitters as beacons difficult). As a result some services which were served by a single transmitter, such as the precursor to the Long Wave Radio 4 service on from Droitwich were closed down for the duration, and thus so this single band restriction was not as severe as it may seem now.

Although these sets were produced by over forty manufacturers, the particular manufacturer of a given set was not revealed to the purchaser, who might presumably have had a preference for a certain manufacturer. It was in fact encoded in the serial number plate to help repairmen (who needed to know from whom to claim warranty replacements), but the table which related these codes to manufacturer was considered "confidential to the trade". Similarly Valves in these sets were given special BVA (British Valve Association) codes which hid the manufacturer, a typical line up would be BVA273, BVA243, BVA 264, BVA211. These might more conventionally be called ECH35 (changer), EF39 (IF amplifier), EL33 (output) and DW4/350 (rectifier). The valves in the Museum's set are all original BVA numbered types and still work! The loudspeaker, unusually the for the time is a permanent magnet design to save wire. It was usual in sets of this era to have an electromagnet field coil which doubled up up as a power supply smoothing choke removing hum from the output sound. The tone control was dispensed with as an unnecessary luxury! The tuning dial dispenses with the complex glass and string reduction gearing commonly used and replaces this with an austere metal plate with an index painted on a disc behind attached to the tuning capacitor.

Manufacturers were allowed to adapt the design specifically with the aim of using up old stock of components which they had on hand which were not required for the war effort as a result numerous small variations appeared, especially as regards the coils. The detector was a rather unusual and unreliable device called a Wesector, a metal rectifier, which was an early form of solid state diode. In fact they were so unreliable that I found the one in the Museum's radio had been removed and replaced with a Germanium Diode in an earlier repair.

The Restoration

I'm often asked what sort of things a restoration of an old radio like this involves, so I'll try and give a brief description. The first decision was how thoroughly to restore it. As so much was dirty and damaged, I decided to aim to restore it so that it looked like it might have done when it was in use, since there are far too many old radios sitting in corners of museums looking so decrepid that I have overhead children looking at such sets, and wondering with horror how their grandparents could possibly have owned such a thing. The finish on the case was so badly damaged there was nothing to be gained in trying to preserve it. The first stage was to separate the two jobs, the case and the chassis. The case was cleaned, sanded, treated with woodworm erradicator and then varnished; the goal being to present the radio as it might have looked when it was in use.

The chassis needed more work; a cursory inspection showed that the wiring was not how it should have been according to the circuit diagram (this simple check was made more difficult by all of the manufacturers' variants). However all of the parts other than the Wesector seemed present. I therefore stripped all parts off the chassis and cleaned everything in solvent cleaners. Components removed were tested individually. This showed that most of them were fine, but the electrolytic smoothing capacitors were faulty (leaky). These were large aluminum cans, three inches long, and modern equivalents were about half an inch long. So that the underchassis looked as close as possible to what it should, I removed the old contents and fitted the new capacitors inside, which was a time consuming and smelly process!

The first assembly I started work on was the rectifier, which thanks to the existence of the two versions (battery and mains) is a separate unit sitting on top of the mains transformer. This arced when switched on and it turned out that the valve holder was no use as the paxolin had carbonized. Asking round a number of friends produced one new in bag from the contents of his voluminous garage. Unfortunately this didn't fit as was and I had to turn special spacers on the lathe in the museum's workshop to correct for its positioning. With this unit working and tested for insulation resistance I was able to turn to the main chassis.

One of the oscillator coils was open circuit, so by carefully melting out the wax in the oven I was able to remove the old wire and rewind the coil using litz wire.

After checking all the parts I commenced the slow reassembly working from a handmade drawing of the underchassis and the original circuit diagram. I had made the decision as a safety precaution to rewire using modern PVC coated wire as 50 year old cloth insulated wire can present a fire hazard.

One of the difficulties which would have been presented when working with a radio like this fifty years ago is that being a superhetrodyne design, unless it is correctly aligned then it won't work at all. Alignment could be a fiddly procedure with early test equipment -- the most a radio repair shop might have possessed would be an AVOmeter and signal generator. The now ubiquitous oscilloscope was only to be found in the larger shops, and its use even there was uncertain, one handbook of the time (it may be coincidental but I found this volume for a dollar in a second hand bookstore in Hollywood!) encouraged the shop owner to put it into the shop window and have someone pretend to be using it all the time to attract customers to bring in the sets for a ``tune-up''. While I have a 1940s signal generator (AVO Allwave Oscillator) to hand, there seemed no need to take the difficult route, so I aligned the set using a spectrum analyser!

On bringing up power to the stages individually (using an isolating transformer!), the oscillator wouldn't oscillate, but that was rapidly rectified by switching the connections on the coil (to correct the phase) and the set was working receiving stations. Sadly not the stations of yesterday though the sound has a similar mellowness due to the poor frequency response of the set!

Alan Bain