Partial Success!

After working out what I was doing wrong in the test set-up, and also discovering the very small note in the service manual that explained that the AUX channel receives regardless of the state of the 'receive' button (yes it is in the instructions on the back of the radio, but mine are in Swedish or something!), I've managed a partial success in retuning the SARBE-5 - my units AUX channel is now no longer the NATO on-scene SAR frequency 282.8MHz, but instead North-East Initial Contact Frequency (ICF N/E) of 290.05MHz.

C54 AUX Rx tuning

As these are single active device receivers, retuning a channel, so long as its within the range of the LC circuit, is just a case of adjusting the appropriate trimmer capacitor. The corresponding trimmer capacitor for the test oscillator also needs adjusting if the self test is to work! If the desired frequency is much further out, then adjustment of the little tapped toroid inductor will also be needed.

Waiting for a signal!

 The AUX channel is working nicely with the test set. I haven't had it on antenna for long enough to see how well it actually receives aircraft yet - that test will need to be done in comparison with a known good receiver, such as my PRC-344, and will need several hours of listening!

C45 EMG Rx Tune

Unfortunately, the main EMG channel is somewhat deaf! Ive adjusted its trimmer capacitor C45 for best reception and its not a patch on the AUX channel. I don't know a lot about self-quenching super-regenerative receivers, so at the moment I don't know what to be looking at to solve this. I suspect since there is so little in the circuit, that its either a dry joint or a poorly transistor.