Gerry,
> I was wondering if it would be realistic to fit something
> like a 4CX250 into the case:
> - I can use a voltage doubler to get about 2Kv for the plate.
> - I can fit a small transformer in for the screen supply.
> - I bet I can fit a small blower in the space.
You might consider a 4CX400 (or the Russian surplus equivalent)
instead of the 4CX250. The '400 should be good for 400 watts
output if you can generate enough grid voltage (might require
a 200 Ohm grid resistor and 4:1 autotransformer input) with the
FT-817.
Further, the 4CX400 should be easier to cool (8 CFM @ .2" back
pressure vs. 6.4 at .84!" for the 4CX250). One of the MLA-
2500 conversions actually uses the original fan rather than a
blower to cool a 4CX400 pair.
The '400 also has a nominal 6.3 volt (vs. 6.0 volt) filament -
it may be a better match to the originally filament winding if
the AL084 used 6.3 volt tubes.
> I'm thinking tetrode because I'd like to have a very-low-drive
> amp that I can use with my FT-817. 200-300w out would be fine.
> (I like QRO and QRP!)
>
> Am I crazy or do you guys have a better suggestion?
Sounds like an interesting project
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