[Arran]

It is odd that they chose the autodyne mixer/oscillator in one version of this set, with the #15 tube, but chose to use a 1C6 in the Code 123 version. The #15 is also a lot more thirsty in that it apparently has a filament that draws 1/4 amp at 2 volts, the 1C6 draws maybe 1/10 of that. If there is something wrong with the tube I don't know what to suggest as a replacement, but it could be something simple like a bad mica cap stopping it from working properly. Another thing to check is the solder joints on the grid caps as well as the condition of the grid cap leads, it does not take much resistance to stop a tube from working as it is typically very low voltage on a grid. I think that a stage by stage signal trace might be in order, like feeding RF into the detector and working your way back to the IF amp, and so forth. A voltage check would be another way if you don't have a signal generator, something is clearly not there.

https://philcoradio.com/library/download...l.%201.pdf

https://philcoradio.com/library/download...l.%201.pdf

Regards
Arran