[Collins] parallel amplifiers

[Gerald]

On Tue, 2005-07-05 at 12:45 +1200, Dave Brown wrote:
> Good point, Jerry, -but easily sorted with a ferrite core double wound 
> xfmr xfmr driving the load-that way you get the advantage of load 
> isolation and the ability to adjust the xfmr turns ratio to suit a 
> standard dummy load-eg 50 ohms etc. Scott Tilley (VE?- I forget the 
> call) successfully used a pair of these combiners recently on LF to 
> combine a pair of 500 watt level solid state amps. 3dB is worth it 
> when you are only a dB or so below the noise on an Argo screen. But on 
> HF, hardly ever.
> 73
>  Dave, ZL3FJ
But the combining job is a great deal more difficult when there's two
tuned circuits in each amplifier where you have to get the same
amplitude and phase from them at the same time. Not impossible, and it
would be far easier with a pair of autotuned amplifiers, but as you say
on HF the propagation and the noise level fluctuates more than 3 dB per
second.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer