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[Elecraft] KPA-1500 failing on 160...AGAIN!

Rick Tavan
 

Does your antenna analyzer show a fault anywhere along the feed line? My old MFJ has found rodent damage out in the middle of the field that was intermittent and power-dependent. Even if the analyzer doesn't see a fault and all known connectors look good, it might be helpful to do a visual along the entire length of the coax. Or, if you have some spare coax, you could try a temporary, total feedline replacement just for the test - quickly routed through a window, etc. That's easier than routing a permanent feedline through walls and along whatever conduits or cable supports you might be using.

GL,

/Rick N6XI


On Fri, Sep 27, 2019 at 6:19 AM Bob McGraw K4TAX <rmcgraw@...> wrote:
 Check for burn marks or carbon traces, both on the inside and outside, of the SO-239 connectors.  These may look good with the antenna analyzer but fail under power.

I've also had PL-259's arc from center pin to shell on the inside. These required removal/ disassembly of the coax in order to actually find the fault.

In all cases, once a flashover occurs, replacement of the connector is the only solution.

Bob, K4TAX




> On Sep 27, 2019, at 6:00 AM, John Langdon <WOYB10051@...> wrote:
>
> If it also happens with a dummy load, and the antenna analyzers shows the same graph as before for R, X, then it is likely one of the connectors between the KPA1500 output and the antenna. The one such problem I had was old jumper I had put in to add an SWR bridge/monitor. It looked okay, and was finger tight, but when I replaced it in an A/B test, the problem went away.
>
> The other time, the antenna had changed its impedance curve, but was still 'okay' and the tuner was trying to retune for it.
>
> 73 John N5CQ
>
>
> -----Original Message-----
> From: elecraft-bounces@... <elecraft-bounces@...> On Behalf Of Jim Brown
> Sent: Friday, September 27, 2019 4:19 AM
> To: elecraft@...
> Subject: Re: [Elecraft] KPA-1500 failing on 160...AGAIN!
>
>> On 9/26/2019 10:26 PM, Peter Dougherty wrote:
>> Any idea where to start looking here?
>
> And if it's a vertical, what about the radial system?
>
> 73, Jim K9YC
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Rick Tavan
Truckee and Saratoga, CA