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Schematic and Parts List |
BACK
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. 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).
The note and keying are about as clean as you're likely to
hear from a homebrew rig.
I originally built this rig in 1998. 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. In
early 2004, I modified the circuit so as to allow VFO
operation.
When I originally built it, I used as many vintage parts as
possible to ensure that the finished product would have a
1950s look. The oscillator and PA tank coils are wound on
1-1/4" diameter red bakelite 5-prong coil forms from an unknown
manufacturer. The tube sockets and coil sockets are steatite
with silver-plated contacts, probably made by E.F. Johnson. The
steatite crystal socket and 807 plate cap are James Millen parts.
The plate current meter is war-surplus item made for the U.S.
Navy by Westinghouse. The PA grid tuning capacitor is a vintage
Hammarlund. The PA plate and loading capacitors were made by E.F.
Johnson. The plate choke is an old Heathkit part. The handles on
the front are WW2 military surplus. The enclosure is a vintage
Bud hinged-top steel cabinet.
The aluminum chassis was made for me by Walt Martin, KB5HOV,
out of 1/16" aluminum. I made the shield around the oscillator
out of two aluminum Bud box lids. Other than fabricating
the chassis, I did all of the metal work and painting myself.
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!).
I run this transmitter off a Heathkit HP-23A power supply.
With +750 VDC on the PA plate and +260 VDC on the oscillator
plate, the transmitter generates about 65 Watts output.
Click on the thumbnails below for full-sized pictures.
The schematic and parts list are also available.
|
Front view |
Rear view |
Under chassis |
|
Left side |
Right side |
Schematic and Parts List |