Help with TX project...

[Keith Rowland]

Chris:  I have a circuit using a single 304-TL which will give you about
550 watts output (CW) with about 15-20 watts PEP input.  It does not
include a modulator circuit, but I presume you can handle that part
separately.

I am not sure, however, that you really want to go the expense of
building a 304-TL amp, unless you have no need to operate higher than th
14-mHz band.  Altho the tube specs say it is good for full output to 40
mHz, you'll find that the high interelectrode capacitances of the tube
will prevent satisfactory operation on 15 and 10 meters in linear
service.

The circuit I have is for a grid-driven single 304-TL, using inductive
coupling for the input circuit.  The output was designed for the
80-meter band, using plug-in type coils (old style stuff).  The designer
had to use vacuum capacitors in a split-stator kind of configuration in
order to tune the whole 80-meter band, and even then the efficiency was
only 55% instead of the 65% you can normally expect for this type of
circuit.  This is because the tank Q had to be loaded rather high to
make it work.

I would submit that there are cheaper, easier, and more flexible ways to
generate high power, but if you want this circuit, send me your
snail-mail address and I'll mail you a copy...no charge! (I'm curious to
see how it works out if you do build it!)

73, Keith



Chris Galbraith wrote:
>
> Does anyone have a QST or handbook article, etc. on a RF final (i.e. to
> be plate modulated) using one 304TL?
>
> I'm designing my first 300-400w AM rig and have some 304TLs that look
> perfect for the RF part (too much for the modulator)--one 304TL at 2kV
> will put out 450W+, but I can't find any designs to follow.
>
> Any leads, info appreciated and will pay all costs!
>
> Thanks to all on the list who've helped me procure pieces so far!! 73,
> Chris KA8WFC
>
> p.s.  also looking for a socket to fit a 304TL and a big plate trannie
> (for 2-2.5kV at 1/2amp or so)
>
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