Updated 20 Jan 2001, AB4YD
Bill's glowbug project #2, 80M VFO rig with 807 final, Rev E

This project was inspired by a series of QST articles by Hayward, W1PH. I based my rig on his April 1962 article, "Have You Tried 160 Lately?". I liked his simple, single band rig. I thought his use of 6V6 tubes, along with regulated voltages, to be a simple but stable alternative to being "rock bound". You can read about his "coffee can" VFO, in the August '49 and Sept '51 issues of QST.

However, I ignored his approach to mounting the VFO part of the circuit in a sturdy coffee can, and just put all of the circuits onto the same chassis. It worked, but it was very microphonic, and this made it difficult to operate.

I eventually chose another route for the VFO, and used a separate chassis for the VFO circuit. Along the way, I also changed the VFO tube to a 6C4, mainly to reduce problems related to heat. The output was very low, so I added a 6AC7 stage. I also went to a 1/2 freq VFO, and doubled the frequency to 80M just in front of the 807 final.

I am pretty happy with the stability of the VFO. The output from the 807 seems a little low, but perhaps it is due to my low B+ and 250V screen. I get about 20 watts into my 50 ohm antenna, even after going thru my half-wave output filter. All in all, it was a fun project.

Old versions of the schematics
Selected info about receiving tubes, from the GE essential characteristics tube manual, date unknown, perhaps '50s or '60s? Tube data for a few tubes I am using

OLD PROJECTS from previous years (1999)

Bill's glowbug project #2, 6AG7 / 12GT5 transmitter (didn't work too good. oh well)
Bill's glowbug project #1, test circuit for oscillator