KPA1500 scare

[Gary Hunt]

Here’s a little thing to check on any transmitter or amp experiencing intermittent swr spikes.

I sent the KPA1500 to Elecraft a couple of weeks ago. I had started to see intermittent swr spikes. A few times it kicked out on swr fault.

At first I thought it was an antenna wire arcing against tree leaves or branches since the canopy is very thick now.  I became suspicious when it did it on the other antenna.  I confirmed 

it wasn't antenna related when it did it using a dummy load.

Elecraft put it through all the paces they do a new amp but they couldn't duplicate the symptoms.

That is until today. They moved it from the burn in shelf to the bench and it started exhibiting the swr spikes. 

It turns out, the SO239 center on output #1 has been expanded by an oversize center pin on a PL259.  Sure enough, the jumper I made that goes from the amp directly out to my common ground point lightning arrestor panel was oversized due to excessive solder on the pin.  It gets disconnected/reconnected fairly often this time of year.  Being expanded is now causing an intermittent bad connection.

The amp gets 2 new SO239s in the morning.

Hopefully my predicament saves someone some trouble in the future.

73,

Gary KC9EE 

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