Fwd: [Collins] parallel amplifiers

[Gerald]

On Thu, 2005-07-07 at 06:24 -0400, Drleborgne at aol.com wrote:
> Thank you all for the wise advice. I was wondering if the four  811"s  of one 
> amp 30L could be worked in parallel with  the four tubes of a second  30L  
> using one of the only one of the output tanks  in common. 
>  Thanks again: Martin

Yes, but it will lead to smoke. To get the right load impedance for 8
tubes and still some harmonic rejection and amplifier linearity you need
twice the tuning capacitance and half the coil inductance in the output
network and will have twice the circulating current which will smoke the
coil. Four tubes are a pain to stop from parasitic oscillations, 8 with
half of them not close makes that a whole lot worse of a problem.

572B will put out more power than 811 in the same size package, but
again to draw more plate current you need that lower impedance load, and
higher circulating current and the power transformer will add its smoke
to that of the output tank.

The 30L-1 is just good for what it does, not a whole lot more. Its too
compact for jacking up the power. Besides which doubling the power is
only half an S-unit and most signals vary more than that just from
propagation variations.

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer