FYI, I found this in the April, 1937 issue of RADIO magazine: The Bi-Push TriBand Exciter or Transmitter, by W.W. Smith, W6BCX. It covers 10, 20 and 40 meters. The design is very clever in that one set of 3 coils and one crystal covers all 3 bands. The coils and 5-pin (tube) crystal socket are wired so that each coil serves a different function depending on what socket it is plugged into. The crystal then plugs into the unused socket! From the article:
"With the crystal in the left hand socket, coil 1 in socket A, coil 2 in socket B and coil 3 in socket C, we have a 40 meter push-pull crystal oscillator driving a 20 meter push-push doubler, driving a 10 meter push-push doubler to over 40 watts output." "To go on 20 meters we insert the crystal in socket A, coil 1 in socket B and coil 2 in socket C. Now we have a 40 meter push-pull crystal oscillator driving a 20 meter push-push doubler. The output is the same as on 10 meters." "To go on 40 meters, we insert the crystal in socket B, and coil 1 in socket C. We now have a push-pull 6L6G crystal oscillator that delivers approximately 40 watts and keys very nicely." The one in the article was built on a wooden chassis with 1/4" jacks for metering. The version I have is built on a steel chassis with switched meters permanently installed. And the article shows glass 6L6's mounted whereas this one came with metal ones. Otherwise, construction is almost identical. A commercial version was available from Radio-Television Supply in Los Angeles as advertised in the back of the magazine for $23.50. Case closed. Now I need to build up a PS and see about all this bi-push business. 73, Don Merz, n3RHT -----Original Message----- From: Merz Donald S Sent: Wednesday, June 04, 2003 10:20 AM To: Old Tube Radios Subject: Need Info on 6A6/6A6/2x6L6 HB TX I picked up a rather cute homebrew transmitter at the Breezeshooters hamfest here in Pittsburgh last Sunday. It's built in a small, slant-front steel desktop cabinet. It uses a 6A6 oscillator, 6A6 buffer (doubler?) and a pair of metal 6L6's in the final. Construction technique is strictly professional and no expense was spared on the parts--Weston meters, ceramic tube sockets and lots of pie-wound RF chokes. It uses one plug-in coil in each stage and the coils are built on tube-socket bases. Link coupling is used to feed the antenna from the output coil. There is no power supply, but that should be the easy part. As usual, I would like to find a construction article or reference to a similar design. If anyone has run across something like this, please let me know. Thanks. 73, Don Merz, N3RHT DISCLAIMER: The information contained in this e-mail may be confidential and is intended solely for the use of the named addressee. Access, copying or re-use of the e-mail or any information contained therein by any other person is not authorized. If you are not the intended recipient please notify us immediately by returning the e-mail to the originator. DISCLAIMER: The information contained in this e-mail may be confidential and is intended solely for the use of the named addressee. Access, copying or re-use of the e-mail or any information contained therein by any other person is not authorized. If you are not the intended recipient please notify us immediately by returning the e-mail to the originator.
