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Re: External Power Supply for the KPA-500

Posted by P.B. Christensen on Apr 20, 2010; 4:35pm
URL: http://elecraft.85.s1.nabble.com/External-Power-Supply-for-the-KPA-500-tp4931334p4932194.html

>I think an internal power supply for the KPA500 with an external ATU from
>Elecraft makes a lot more sense.

I like the remote-ATU idea, especially, if it incorporates an auto-tune
feature as well as a means to integrate switched antenna ports.  A 500W
auto-tuner with say...six SO-239 ports would be great.  Those needing more
ports?  Perhaps an expansion capability.

I may have missed it, but I would like to know more about the KPA500's T/R
function -- namely, is it 100% electronic with PIN diode switching?  Or, are
frame and/or vacuum relays used at the amp input and output?  A silent,
PIN-diode switched amp would be commensurate with the K3's excellent T/R
function.

Presently, I am using a SPE 1K-FA amp and although the amp is compact and
has been reliable for me, the T/R switching function is quite noisy.  To
deal with the noise issue, I modified an Ameritron QSK-5 and the T/R
timing/bias function is now better than the stock system:

http://72.52.250.47/images/QSK-5-Interface.pdf

Added to the noise is the fact that the SPE's cooling fans begin getting
noisy when the PA reaches above 100-degrees C.  By the time the PA reaches
150-degrees C, it's as if an F-18 Hornet is taking off from my desktop.   If
the Elecraft folks can apply their same know-how to the KPA500 as they did
with the K3's cooling system, I think few folks will be complaining about
cooling noise.

Paul, W9AC


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