Here is the single-813 crystal oscillator transmitter , designed by RCA and exhibited in their advertisement on the back page of a "QST" magazine in 1938, and published by RCA in their HamTips bulletin, vol. 1, no. 4 , dated December 1938. This transmitter's output is 150 watts of CW or 100 watts of plate-modulated AM telephony. It seems obvious that this circuit and the 5 meter push-pull 807 oscillator transmitter were both designed by the same RCA team. The same caution about screen voltage applies here as well. In my opinion, the keying circuit leaves something to be desired. Perhaps cathode or grid-block keying should be tried. They would certainly be safer.
Here is the schematic and parts list.
Click here to view and/or print page 1 of the scanned copy of the RCA Ham Tips referenced above, which discusses this transmitter and its features, and click here for page 2.
And here are some photos of one of these built by Jack Meadows, W7QQQ, of Arizona. I have often heard this rig on the air on one or the other of the BA frequencies, 3547.5 Khz., and/or 7050 Khz, and have worked him when he was using it. It sounds very nice.
Here is Jack, his station and the first iteration of his Single-813 Crystal Oscillator Transmitter on the far left.
Jack Meadows, W7QQQ, his station and (on the far left) his first 813 oscillator.
Here are some other photos of his present iteration of the 813 oscillator rig.
What is that rig on the left? It sure looks like that little Hallicrafters novice transmitter, doesn't it?
Boy! That sure doesn't look like a 6DQ6 to me! (The transformer is the filament transformer for the 813. The HV power supply is below the table.)
So, "go, thou, and do likewise".