Generally speaking single or paired has small practical differences in
performance of an HF amplifiaer but often, the price to buy two (real
transmitting) tubes is higher than the price of a single and equivalent
larger tube. Moreover, a single tube has a smaller output capacitance
than a paired and this helps to keep the matching network Q within
reasonable limits on high HF bands, even using standard plate
capacitors with high minimal capacitance.
I've no experience with 4CX1600 and SVETLANA reliability with small
tubes, in any case the use of tetrodes in place of triodes in GG linear
amplifiers hasn't any inherent advantage.
The 3CX800A7 was a great tube, but its production has been discontinued
by EIMAC in favour of 3CPX800A7 in trying to eliminate some problem.
Unluckyly, also a lot of the 3CPX800A7 sold in the last year (nearly
all) are reported to be defective or, better to say, to become
defective (high grid, low output) after a very short time (hundred
hours).
73,
Mauri I4JMY
> ---------- Initial message -----------
>
> From : owner-amps@contesting.com
> To : amps@contesting.com
> Cc :
> Date : Thu, 10 Aug 2000 18:25:05 -0500
> Subject : [AMPS] single tube vs. twins
>
>
>
> Having run only 3-500Z's most of my QRO career, can someone enlighten
me on
> the pros/cons of a single 4CX1600B vs. two 3CX800A7's? I use an amp
only for
> casual DX and nets, and work contests for fun only - I have never
submitted
> a claimed score. But my Swan Mark II, like me, is pretty long in the
tooth,
> and I am thinking of "upgrading" the power now that I have an FT-1000D
> available as a driver.
> Thank You,
> Jerry W5KP
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