Welll... If you look inside some of the higher powered 2-meter amps you
will find a pair of Push Pull amps running in parallel . You may even
find 4 P-P amps combined in there. SS HF amps are a whole series of
amps running in parallel. On 2-meters I've taken a pair of 160 watt
amps, fed them through a power divider and ran the output into a
combiner. One amp does the keying and the other is the slave. They will
not work using the auto keying in both, or at least I was never able to
get it to work without blowing one of the keying transistors. Tuning
them up is a balancing act between the input and output tuning of both
amps and they do interact.
As it works on VHF I'd expect it to "theoretically" work on HF, but I'd
expect to need tuned inputs on both amps and that'd be a lot of tuning
for the initial tune up or frequency excursion on any band for just 3 db
max.
donroden@hiwaay.net wrote:
> Not saying anybody WOULD,,,,,,,,,,, but if you COULD.....
> parallel a pair of SB-220s on a single band ?
> Wilkinson Power deviders / combiners for zero phase combining?
> A 90 degree network on the input and opposite 90 degree on output ?
> Run them in push-pull ( 180 degrees )
>
> Assuming all splitters/ combiners would be made from coax.
>
> Or, just use short runs of equal length coax and a coax tee for the inputs
>
There would be a bit of a mismatch that would have to be tuned out as
each amp would see 25 ohms at both the input and output. If the matching
networks would handle it, you'd basically tune for maximum smoke at the
output of the combiner. With lots of coax and at those power levels I'd
expect there might be a few problems.
> and accept a 2:1 drive mismatch ?
>
>
You might want a tuned input on each and maybe a few spare tubes to
allow for experimentation. <:-))
73
Roger (K8RI)
> Hummmmmmm
>
>
> Don WA4NPL
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>
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