[Elecraft] KPA500 Issues

[Kent Tiburski]

Hi guys!

  Seems I found the solution to my problem.  I put ferrite cores next to the
amp AND I forgot the PTT line so that was added.  Added one to the AC line,
there's two now.  Now I'm able to get acceptable VSWR and run 350 watts out.
I never really thought that it was the amp's fault but my installation.
That's good cuz 6 meter prop is in so I'll work a few more Q's today!  

  I suppose that there is a lesson learned here, ISOLATE your installation
either by distance and/or add ferrite.  I was pretty suspect that the
problem was the close proximity to the antennas.  FYI, but thanks to all for
your technical support!  It wasn't the product, it was the guy (that would
be me) and my installation that was the culprit.

  Having said that, does the 500 maybe need a little more RF hardening?  Not
a EE major, just asking the question.

73, Kent, K6FQ







-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Kent Tiburski
Sent: Sunday, June 10, 2012 11:28 AM
To: 'Bob'; elecraft at mailman.qth.net
Subject: Re: [Elecraft] KPA500 Issues

Thanks Bob!

  I actually did that and added those snap-on ferrite cores.  I cleaned up
things a lot!  I'm starting to think that there may be other things going
on.  I took the advice of others that replied.  Things such as using a dummy
load, no problems.  I put the amp in STBY and when running 100 watts thru it
the VSWR was less than 1.5 to 1 and forward power was 100 watts (indicated
on the amp).  I put the dummy load on the other end of my run of coax and it
was fine.  Even with the extra balun and ferrite cores me thinks that it's
either the length of the coax or I have the antennas too close to the shack.
My 6 meter yagi is laterally about 30 feet from the rig/amp and the R8 about
36 feet.

  Anyone else have any ideas?  Thanks!

73, Kent, K6FQ

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Bob
Sent: Sunday, June 10, 2012 10:59 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] KPA500 Issues

The R-8 is a radial-less vertical.  Unfortunately it has a tendency to put
all sorts of RF down the coax as the "counterpoise" system is too short
given the wavelengths involved.

You might want to buy a heavy-duty coaxial choke from DX-Engineering like
the

http://www.dxengineering.com/Parts.asp?ID=1474&PLID=166&SecID=81&DeptID={112
450B5-E9E3-4F36-9166-E52FA128D019}&PartNo=DXE%2DFCC050%2DH05%2DA<http://www.
dxengineering.com/Parts.asp?ID=1474&PLID=166&SecID=81&DeptID=%7B112450B5-E9E
3-4F36-9166-E52FA128D019%7D&PartNo=DXE%2DFCC050%2DH05%2DA>

I used a R8 for years and had trouble even with 100 watts of power.  I can't
imagine how bad it would be at 500 watts.  Your station ground is going to
have to be top notch if you want to avoid trouble.

Good luck!

73, Bob, WB4SON
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