----- Original Message -----
From: Dr. William J. Schmidt, II <bill@wjschmidt.com>
To: Steve Thompson <g8gsq@qsl.net>; <amps@contesting.com>
Sent: Wednesday, July 16, 2003 3:12 AM
Subject: Re: [Amps] Revisited: Power Combiners, cheap amps.
> Well, read
http://www.communication-concepts.com/appnotes/AN758300Sharp.pdf
> pages 10 and 11 for yourself. If one amp fails, the load resistance
> changes...
In the power splitter, yes, one amp failing will cause the input impedance
to change - the change will be less with the terminating resistors than
without. That's looking at the effect between one port and the combined
input/output. In the output combiner, one amp failing will not change the
load seen by the other amp if the combiner is working perfectly and
providing total isolation between them. If isolation is finite, then there
is some change, depending on the isolation.
To some extent, I guess it's different ways of looking at the same thing.
The resistors provide isolation, and you can't have high isolation without
good VSWR - it's a metter of which way round you choose to put the cause and
effect. There's a fairly good article at
http://www.minicircuits.com/appnote/psc2-2.pdf
Steve
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