[Elecraft] KPA500 troubles

[Jack]

The amp was factory built, about two years old and has worked fine till yesterday.
Anyway talked with Elecraft, the amp is going back. They said there are some updates needed in addition to the repair. I will post the fix when I get it back.
Thanks to all the other replies.
Jack
W4GRJ

On Oct 19, 2015, at 12:27 PM, Ron D'Eau Claire <ron at cobi.biz> wrote:

Jack, did you build the KPA500 yourself? In any case, one point that can
cause trouble is where the hot (center conductor) lead goes to the RF Output
connector. See Figure 40 on page 28 in the kit assembly manual (if you
bought yours built, you can download the manual from the Elecraft web site
(http://www.elecraft.com/manual/E740149%20KPA500%20Kit%20Assembly%20Manual%2
0Rev%20F4.pdf). That lead needs to be dressed away from the sharp edge of a
shield as shown in the figure to avoid the possibility of an RF arc. 

If that's the problem, just move the wire away as described in the manual. 

What the KAT500 does not tell you is the SWR on the line between the amp and
the ATU. If it's fairly high you can build up some substantial RF voltages
there. 

73, Ron AC7AC 

-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of W4GRJ
Sent: Monday, October 19, 2015 5:20 AM
To: elecraft at mailman.qth.net
Subject: [Elecraft] KPA500 troubles

All of a sudden my KPA500 is misbehaving. It sounds like it is arcing inside
and smells the classic something is burning smell. SWR LED's are dancing
upwards as it arcs.
KAT500 tuner has the SWR around 1.3:1

I will probably send it off to Elecraft but thought I would ask here for
suggestions to look at before I send it off.

Thanks, Jack
W4GRJ



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