[Elecraft] External Power Supply for the KPA-500

[Paul Christensen]

>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