[Elecraft] Failure Of KPA500 - Ideas?

[k6rb at baymoon.com]

Richard,

When you key the amp using the cable from key out (K3) to key in
(KPA-500), do you see the little asterisk next to the frequency on the KPA
display? That's the symbol that shows the I/O module key-in line is
getting pulled to ground by that cable. If you're not getting that symbol,
I would suggest that you have a problem with the I/O module or that cable.
If you are getting that symbol, but seeing no RF out on the LED display,
it sounds like it's a problem in the PA module (which would be consistent
with a sequential drop in power). I'm assuming you've gotten no fault
indications and the voltage is within specified limits.

Rob K6RB


> Elecraft Group.....
>
> Just working CW on 15 Meters with my K3 and KPA500 when I noticed the
> Power Output LED Indicators starting to drop and continuing until all
> were out and the PA dropped out of the Keyed Mode.  With KPA500 is
> attached with the AUX Cable to the K3 the Symptoms are: (Note:  Unit
> has been in operation w/o any issues for 3 to 4 weeks)
>
> 1. Unit is powered up
> 2. In the "OPER" Mode, No Keying Up or any indications of any power output
> 3. In the "STBY" Mode, LED's indicate both 100 Watts and a <1.5 SWR
> Reading
>
> Again in the "OPER" Mode there is no indication of either a Relay
> Keying Up or Power Output.  Obviously these are related.  Relay not
> keying up prevents any Drive to get to the KPA nor any Power Output to
> be generated.
>
> I added back the TX Keyed Line from the K3 to the KPA and still on Po.
>  I have also taken the unit apart (I built the unit) and checked the
> obvious items.  I.E. Wires Pinched or Shorted.  Connection Loose.
> Proper Wire Dressing, "wiggled" any and all boards in case of any
> intra-board contact issues......etc.  Nothing seems to be out of line
> nor is there any "smell" or "odor" of any tell tail component
> failures.  Unit has been put back together and retested with the same
> symptoms.
>
> I will be calling Elecraft later this AM but in the meantime I thought
> I would send a note and look for a possible solution from the
> "Elecraft Brain Pool".
>
> Thanks,
> Richard "Dick" Griest - WB4VMH
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>