Posted by
Mike Markowski on
Mar 08, 2007; 3:11am
URL: http://elecraft.85.s1.nabble.com/RE-Problem-with-KPA100-power-output-high-current-tp444353p444355.html
Courtney and all,
Courtney Krehbiel wrote:
> ...The real cause of my trouble was dead 1N5711 diodes in the internal SWR
> bridge circuit. The diodes in both the KPA100 and KAT100 were fried...
> With the RF detector circuit dead and
> measuring no output power, the K2 feedback control process just kept
> trying to drive the unit harder until it reached full bore and
> high-current would ensue...
I had exactly this problem a few weeks ago. In my case, though, it
seems a near lightning strike (in winter!) or some other ESD source
zapped just one of the 5711s in the bridge. But after that 3 diodes in
the t/r switch shorted, followed by scorching a few resistors in the PA
area as well as one in the t/r switch. Ouch.
With Gary's patient help as well as a few component replenishments from
Scott (parts@elecraft) I was back in business again. My lesson learned
is disconnect the antenna even in winter time. It still feels good to
have the rig working again!
73,
Mike ab3ap
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