If you want to buy a power supply, two great candidates are the Heathkit HP-23 and HP-23A. You can either build your own power supply or buy a commercially-made supply. You can use anything from +200 VDC to +300 VDC for the low B+ supply, but don't exceed +300 VDC because the maximum rating of the 6AG7 is +300 VDC. Power output, of course, will be a function of plate voltage. You can use anything from +500 VDC to +800 VDC for the high B+ supply.
Plate current at maximum output power should be in the vicinity of 110 to 120 mA with a high B+ supply of about +750 VDC. There's some good information here, and some important safety information that you must not skip. I suggest you read the following text carefully first, before you spend any time with the schematic. With +750 VDC on the PA plate and +260 VDC on the oscillator plate, output power is about 65 Watts.īelow are several photographs of the finished transmitter:Īt the very bottom of the page, you will find the schematic and parts list for the 807 CW transmitter. I power this transmitter with a Heathkit HP-23A power supply.
I guess the only thing keeping the rig from looking totally 1950s authentic is my use of Dymo labels instead of vintage water-slide decals (and that's only because I haven't found any yet!). Other than fabricating the chassis, I did all of the metal work and painting myself. I made the shield around the oscillator out of two aluminum Bud box lids, held together at the corner by some scrap angle brackets. The aluminum chassis was made for me by Walt Martin, KB5HOV, out of 1/16' aluminum. The enclosure is a 1950s Bud hinged-top steel cabinet with black wrinkle finish. The PA plate and loading capacitors were made by E.F. The PA grid tuning capacitor is a vintage Hammarlund. The plate current meter is war-surplus item made for the U.S. The steatite crystal socket and 807 plate cap are James Millen parts. The tube sockets and coil sockets are steatite with silver-plated contacts, probably made by E.F.
The oscillator and PA tank coils are wound on 1-1/4' diameter red bakelite 5-prong coil forms from an unknown manufacturer. I used as many vintage parts as possible during construction to ensure that the finished product would have a 1950s look. In early 2004, I modified the circuit so as to allow VFO operation. It started out with a 6V6 in the oscillator, but I rebuilt the oscillator section in the autumn of 2003 and changed the tube to a 6AG7. The note and keying are about as clean as you're likely to hear from a homebrew rig. The oscillator design is directly out of any 1960s ARRL Handbook, and the basic design for the final came from one of my favorite project books, '104 Ham Radio Projects for Novice and Technician' (TAB Books, 1968). I've built many transmitters over the years, but this one was definitely the most fun! It uses a 6AG7 crystal oscillator to drive an 807 final.