[Argus25]

Reading through this whole thread is a reminder that when building any superhet radio, be it a kit or a self designed one, when it is completed, all parts of the system need to be tested & checked.

Firstly the supply current to the audio & driver stages and the whole radio. At least one check with a 1kHz sine wave and audio into a dummy load, to check that the audio stages are basically distortion free and have around the correct output level.

Then a sweep of the IF (ideally with a signal generator and scope) to ensure the IF is stable, has about the correct bandwidth & gain.(if not the bypass and grounding arrangements and AGC system checked and modified if required) Then a check of the local oscillator level and frequency range. Then an overall radio sensitivity check.

There are a lot of variables which could sabotage the operation and performance of the radio kit, so these checks, on a newly built unit, are definitely required. If they are not done you end up with all the reports of bad performance or failure to operate, many a case it will just be one unsuitable part or component or something simple. Without the systematic tests, the faults will remain unsolved and elusive. A lot of the time you can "get lucky" and everything will appear to be ok first pop, but as shown by the remarks on this thread, it is a bit hit & miss.