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Old February 14th 05, 02:52 AM
Frank Gilliland
 
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On Sun, 13 Feb 2005 07:09:44 -0800, Jay in the Mojave
wrote in :

Hello Frank:

Yes we did have better luck goin the single phase route. But do have
single and three phase avialable.

After making a new type of quad/yagi type of beam for 2 meters and
listening in on the ZOO channel 147.435 MHz and a few other Los Angles 2
meter repeaters I heard a conversation talking about a 10KW broadcast
transmitter that had some sort of shipping and or fire damage, but the
power supply was in good shape, down in San Pedro California. I called
the guy and will have the place and insurance point of contact Monaday.
But it does use 220 or 240 single phase, we will see.

If this was really for a 10 KW Transmitter tha used a pair of 3CX3000 or
a single 3CX6000 then this may be the ticket.



The problem is that you are getting into a power range that usually
requires custom-built components. It would be much easier to build up
a transmitter around a 10kW transformer, instead of building it up
around the tubes which are pretty much standardized components.

But why are you even messing with triodes? Unless you like to
constantly readjust the neutralizing cap, or you run them grounded
grid and pump in a kW or so, you might be much better off with a
couple large tetrodes. Broadcast pulls are cheap, in regular supply,
are usually 80%+, and will last a long time running them AB1 which
requires almost no drive power at all. Get even bigger tubes and you
can reduce the heater voltage which will make the tubes last even
longer. Plus, if you use resistance coupling then you can open up the
input bandwidth -and- disregard the need for neutralization, with much
better efficiency and longer tube life than grounded-grid triodes.

Just something to think about.




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