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Author Topic: Classic 6L6 Homebrew Transmitter Help  (Read 40132 times)
AB5S
Member

Posts: 32




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« Reply #30 on: December 24, 2012, 08:23:21 AM »

.....A more important issue that concerns me is high crystal current. I have some crystals purchased from AF4K, many of which are retrofitted with small modern crystals inside vintage FT-243 cases. This is a fantastic service to hams wanting to run older equipment but it's well known that such single tube transmitters are hard on crystals. I in fact blew two of my "modern" FT-243's while experimenting with this project. It seems fine with genuine old-stock FT-243's though. Anybody know an acceptable level of crystal current for various type fundamental crystals? For this reason alone there's a good argument to use a MOPA rather than a single oscillator transmitter like this.

BryAF4K  is a good guy, an honest dealer and he's doing us all al service
providing crystals at reasonable costs.  That being said, there are limits
to what can be done with the tiny replacement crystals stuffed in the FT-243 cases.
In some circuits- especially those with ECOs, they work fine.  In many others,
they just don't provide the drive needed to develop full output.  In power oscs,
they will likely blow-up.  I'm working on alternatives for my 1935  RK-60 power osc. transmitter.

You can give them a try.  If you have original, big-blank crystals, take good care of them.
They ain't making more.  73 D.S.
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