Wartime Civilian Receiver - Part 4: Bringing it back to life

With the chassis work completed, the time had finally come to see if  my WCR would work.

We can bring it back to life!

The restoration had included replacement of all potentially faulty capacitors and wiring, so the possibility of anything going bang when the power was applied was minimal. Some safety checks were still necessary though before power was applied.

I used my Robin 3111 tester to check the continuity between the earth pin of the plug and the chassis, and the isolation between chassis and the mains. This showed a fraction of an Ohm for the earth continuity, and infinite resistance between both sides of the mains and earth (after checking that the set's mains switch was on!)

A multimeter could be used for this, but a proper insulation tester or Megger is preferable as it applies a higher voltage for the insulation test.

Robin Model 3111 tester

A WCR is unlikely to receive anything without an aerial, so I connected a couple of metres of wire to the A1 socket, more than enough to pick up the local AM Gold transmitter around 5 miles away.

I use a lamp limiter when powering unknown sets for the first time. A 100W 240V lamp connected in series with the live supply wire has negligible effect if the radio is working correctly; the current drawn is insufficient to heat the filament and it's resistance is very low. However,  if a fault causes the radio to draw a lot of current the lamp lights, the filament resistance increases and the fault current is safely limited...well that's the theory anyway!

Chassis re-fitted ready for testing

Power was applied, valves began to glow and the lamp limiter didn't...and after 30 seconds or so I could hear noise from the loudspeaker.

It lived!

After removing the lamp limiter I tried again. Tuning around I was pleased to hear three or four stations, but something wasn't right. There was a loud whistle that decreased in frequency as a station was tuned in, dropping to almost zero, but then rising in frequency again as I carried on tuning past the station.

If you read my earlier post you might remember that I had been a bit clumsy in removing the BVA246 IF amplifier valve early in the restoration. It turned out that I had broken the earth connection to the red metalised paint on the glass envelope, and in this receiver this can cause IF instability.

Original BVA246 (EF39) with damaged screening

Fitting a good EF39 borrowed from another radio confirmed that this was indeed happening, and a New Old Stock CV1053 (a military equivalent) was duly bought and installed.

It was great to hear the set working again!

All that remained now was to sort out the rear panel and cabinet labels, and take some pictures of the finished radio. I'll put this all in the final part, coming soon.

Keep Listening!