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Re: KPA 500

Posted by James Hall-2 on Sep 10, 2010; 5:20pm
URL: http://elecraft.85.s1.nabble.com/KPA-500-tp5516915p5519139.html

Hello All:

 

I guess I'll throw my 2 cents worth in the pot. I have been waiting for a
QRO amplifier from Elecraft for some time now. I've truly enjoyed all my
Elecraft products which include four radios. The build of the K2/100 was the
richest experience and I learned a very great deal. The QRO amplifier was
talked about and a prototype was displayed many years ago now.

 

I finally decided to put to use my 20 year old Kenwood TL-922A amplifier.
The problem was that it required a buffer between the newer radios and this
amp, it was a noise maker with its heavy relay, and had problems with flash
over most likely due to VHF parasitics. There is a great deal of information
on upgrading this finely built amplifier on the internet and I finally took
the plunge to do the modifications. It took a couple months to gather up
items needed and do the mods but it now has an electronic cathode bias
circuit, full QSK using the little Gigavac GH1 vacuum relay, a step start
circuit using that big noisy relay (it only snaps shut once now!), no ALC
circuitry, modified VHF parasitic suppression, and I can drive it equally
well with my Drake T4XB or my K3. The project was fun, I learned a very
great deal, and the result was excellent. No more flash-overs and clean
output. And the old girls, the 3-500Z's, are still shining well.

 

The one thing that is missing is 6M amplification. This is where the new
Elecraft KPA-500 will do well. I believe the new 6M Alpha (RF Concepts) amp
will cost more than the KPA-500 but it will give you 1500 watts - easy. The
new solid state technology with light-weight power supplies is certainly the
way of the future and the small matching Elecraft footprint is a definite
plus especially for DXpeditions. Will I buy one ? It depends. It will be
very hard to part with my modified TL-922 since it is now 'personalized'.
And with the experience and knowledge gained from that process, I may decide
to build a 6M amplifier to round it all out. Now if Elecraft were to come
out with a KPA-500-6M 6M only amp . J

 

73, Jamie

WB4YDL





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