[Amps] Tube suggestion needed - 6 and/or 2M ~500W level with 800-1kv on plate?

[Carl]

There arent many tube choices at that voltage except for a couple of heat 
sinked 8560's or 8072's. Those tubes and their beryllium insulating blocks 
are fairly common from scrapped commercial FM gear as well as some lab 
equipment. Another tube, but scarce and expensive, is the 8873.

If you want to rework the PS from a FW bridge to a doubler you can use the 
same tubes with more output up to the limit of the PS and number of tubes 
used.

However the physical layout is far from ideal for 2M and would require a lot 
of sheet metal work.

One idea Ive not tried is to take a regular 4CX250B and remove the radiator 
(they are soldered on) and then make up your own solid block. Or saw off one 
side of fins and replace with a brass plate. Then mount a muffin fan on top 
of the cabinet to draw out some heat thru the remaining fins while another 
fan blows on the heat sink.

Just some off the wall ideas to think about.

Carl
KM1H


----- Original Message ----- 
From: "david feldman" <wb0gaz at hotmail.com>
To: <amps at contesting.com>
Sent: Saturday, June 21, 2008 11:01 AM
Subject: [Amps] Tube suggestion needed - 6 and/or 2M ~500W level with 
800-1kv on plate?



I've got old Dentron GLA-1000 sweep tube amp; mulling over what to do with 
it as I don't really need for HF. They are a convenient package size for 
~500W class amp, so wondering if there are any tubes worth investigating 
that would be workable on 6 and/or 2M but not need extra plate voltage over 
what the GLA can do (I think around 900V.) I'm not considering sweep tubes 
for 6M (with all due respect to the Drake TR-6 and TC-6) and they're 
obviously not an option at all on 2M.  I'd like to avoid reworking the power 
supply with voltage doubler and all that... Any suggestions? Very tks, Dave.

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