As a result of my adventures in simple one and two tube sets I got interested in WW2 Spy radios. I found a very interesting set called an adapter nut on one website. Knowing it isnt a phrase used either here or in Germany I guess it is just the name this website give it. I searched as much as I was able to and found many references to German agents using "Adapter Sets " to transmit from normal household receivers found in North America and the UK. Apparently they were built by German hams as required. No specific circuit I could find but they had to be able to perform the same way. Crystal control was used. The set did not require the agent to bring a tube. He (or she)only needed the adapter set , an antenna of some sort, his assigned crystal and a CW key of some sort. The agent found a radio of the right pinout , removed the final audio tube, plugged in the adapter set , plugged the tube in the adapter, plugged in their crystal , hooked up key and antenna and they were on the air. So I made one. I used a light switch box with a straight cover(no holes) I used a normal crystal osc circuit but made the output tank slug tuned with fixed capacitor. It work right away on tune up so I put it on the air. Within the hour I had worked WB4FDT "Pip" in Baltimore MD some 326 miles away ATCF. I was impressed. I have a 1938 CGE H4B battery power set. The final is very similar to the pinout I used (7AC or 7S which allows for about 10 different final tubes) except the 1C5E final is directly heated. So I powered the old set up then shut it off, plugged in the adapter as required and powered it back up. Took about 3 minutes total. It worked as they said it did even on this kinda odd radio. More QRP the hard way. I am having a lot of fun as you said. I only have one crystal in the traditional CW section of 40m and it is at 7050khz. Got to find a couple more. Perhaps 7020 and 7030. (FT 243) Never had so much fun!
donVe3LYX
