Failure Of KPA500 - Ideas?

[Richard Griest-2]

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
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[k6rb]

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:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>

______________________________________________________________
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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html