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![]() "Uwe" wrote in message ... So now is the time to start the construction of that more advanced version of a starter transmitter using two 807 as finals, who was mentioning that design way back?? You almost have to put those 807s in push-pull, for aesthetic reasons. That is easier to do with plug-in coils than with a bandswitch. Then you need a dual variable to tune the dual coils. Swinging link to adjust coupling to the antenna. This stuff shows up at hamfests sometimes. You may find someone's old homebrew rig for sale and you can salvage the parts from it. The Handbooks Tim mentioned will have all the info you need. I started out with a 1953 Handbook but I can't remember what projects were in it anymore. They're all over eBay, don't pay too much. Tim's also right about the 1625 tubes. They're the same as 807s except for the filament voltage and socket. My second transmitter (the first was a single 6V6) used an 807W, a compact version of the full-size bottle, as the PA. I used a Calumet baking soda can for a shield. While you're cruising the hamfests, look for an RCA Transmitting Tube manual, a small paperback. They're fun to read and there's some application info in them, as well as the usual datasheets. I used to use a mercury-wetted relay to key my tube rigs. They're really fast and make a nice ticking sound when you're keying. They also isolate you from the keyed voltage and allow the use of most modern keyers. Definitely in keeping with the period, too. They look like octal vacuum tubes with metal bulbs but they're shiny, not black. 24 VDC is a common coil voltage. Do you hang out on the boatanchors group? You might be able to turn up some parts and lots of info over there. (Note that I have quit trying to convert you to solid-state! You are obviously a lost cause. : Have fun.) 73, "PM" |
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