One consideration that I hear often with relation to vacuum tube circuits is to be very, very careful of the high voltages that are typically involved. And, I completely agree. What if the highest voltage was 45 V though? A battery operated rig would seem more useful to Agent Sonya in my opinion. I went searching for something that might take less voltage, and therefore be safer for construction by the gang and I. It didn't take too long to find something that might work as a basic concept, although I do understand that the operating frequency of the circuits shown below wouldn't transmit long distances. Here are the schematics from the 5 meter rig outlined in the March, 1936 issue of Radio Craft on page 525 Notice that at first glance, the highest voltage involved is from a 45 V battery. The 'interruption-frequency' coil concerns me a bit because I don't know what it's for yet, and it looks like a transformer. Upon further reading, and squinting at the acro...