The venerable 19 set is well known to most radio hams of a certain age, I guess that includes me! The 19 set is a  British WW2 HF and VHF transceiver that was used in tanks during the war. Many of these units appeared on the surplus market during the 50’s and 60’s and were often snapped up by Ham radio operators as a quick and easy way to get on the air. The 19 set covered  2-8 Mhz on HF and also had a VHF  radio on 235 MHz. The VHF radio was used for short range comms while the HF radio could be used to cover 100 or more miles. The radio was good for AM, CW and MCW, but despite having an 807 in the PA could only manage at best 5 or 6 watts. Generally speaking, many of these units were modified by removing the VHF section (the B set)  and only using the A (HF) set for AM and CW.

I first owned a 19 set shortly after acquiring my RAE back in the early 80’s. Some of the components for the PA had been removed and after building up a power supply I managed to get it to work.

This particular unit came from an SK sale from the shack of Brian, GW4KYT. It is in very good condition but has had some modifications including removal of the B set and many of the capacitors have been replaced.When I tried to test it the receiver worked OK but it was transmitting on a different frequency. Further inspection revealed it was missing the BFO. The transmitter section works by using a 6K8G mixer before the driver (EF50) taking the signal from the receiver local oscillator and the BFO and producing a  differential output corresponding to the transmitted frequency.

After looking at this in more detail it appeared that the BFO coil had been removed. Fortunately I had a box full of 19 set spares which included a couple of coil units in reasonable condition. It was also helpful that I just happen to have a couple of working 19 sets in the shack to compare the components and wiring with….

I managed to use this 19 set as to work out the wiring as the circuit diagram I had did not appear to be exactly the same as my radio, this may be due to the fact that there are a number of variations of the 19 set.

The circuit diagram above was the one I used to trouble shoot this 19 set. There is a lot of info available for these sets on the VMARS site if anyone is interested.To cut a long story short I managed to successfully re-install the missing coil and it does actually work although I appear to have some hum on the audio which I guess is from the power supply. I’m not planning to use this radio ona regular basis as the performance is pretty poor but it was a good proof of concept to try and repair and get it to work again.