[Elecraft] KPA500 RFI problem

[David Gilbert]

That doesn't sound like RFI.  My guess would be that something is 
arc'ing over between your amp and the antenna.  That could be happening 
at any one of several places (particularly at connections or inside the 
balun).  If it's close to the shack you could probably hear it ... if 
it's in the feedline or at the antenna you might be able to see it at 
night or discover a carbon track somewhere.

73,
Dave   AB7E




On 1/8/2013 6:06 PM, Ron W3ZV wrote:
> At least I'm pretty sure its an RFI problem. I have a K3, KAT500 and the KPA500 connected as recommended with Elecraft DB15HD cables. The antenna is a 120ft. doublet fed with ladder line to a 4:1 balun and 10ft of coax to the KAT500. I have a comment point ground to a ground rod six foot from the shack. I have operated the amp at 400+ watts from 80m to 6m. The only band that gives me a problem is 12m. When I am operating at 400 watts ssb, the amp will fault with a high swr indication within 5 to 20 seconds. Immediately prior to the fault the swr on the amp display was 1.2:1. Reducing power to below 300 watts seems to avoid the problem.
>
> Assuming the consensus is that this is RFI, what would be the most likely suspect? Coax cables in/out? DB15HD cable? Power cable? What's the easiest way to diagnose and correct the problem? Thanks
>
> Ron W3ZV
>
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