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Re: Preamp / SWR issue



Hi Nate,
  either I'm misunderstanding what your trying to say or I think your statement is wrong.

If you add a "large amp" your SWR will not change unless the impedance of the amp
is different than your rig, amps are not bi-directional and do not pass reflected
power from the antenna back to the rig itself through the amp.

 If you have your  rig--coax--amp--coax--antenna, then you will have a swr ratio
between the rig and the amp and a different swr between the amp and the antenna.

I guess if you had a really huge mismatch then depending on the design of the amp
it might throw  off the input impedance and change your swr  but if its that bad you
have a bigger problem to fix   :-)

Please explain where I'm going wrong here...

73
Kevin WA6FWF
Amsat-UK #6505


----- Original Message ----- 
From: "Nate Duehr" <nate@natetech.com>
To: <amsat-bb@amsat.org>
Sent: Wednesday, June 14, 2006 9:28 PM
Subject: Re: [amsat-bb] Preamp / SWR issue
SNIP!
> One for the books, although it probably isn't your problem, but remember that SWR as seen at your transmitter is the reflected 
> power that makes it back down through your co-ax to the transmitter.  If your return loss coming back down the co-ax is high 
> (thus, losing you received signals too) if you add a large amp, you can sometimes now "see" a lot more reflected power make it 
> back down through the lossy co-ax cable.
SNIP!
>
> Nate WY0X
> ----
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