KPA500: strange behaviour - any ideas?

[VK7JB]

Hello Group,

I'm running KPA500 #1076 with firmware 1.23 installed.  It's
connected to my K3 via the elecraft AUX cable and is connected to my
PC via serial to USB adapter cable using FTDI chipset.  Interfacing
functions with the PC and K3 work flawlessly.

It runs perfectly apart from one intermittent peculiarity: 
unpredictably, when in QSO, the amp will switch from operate to
standby mode.  This does not trigger the Fault indicator and no fault
# is ever reported by the KPA500 to the utility program or to the K3
LCD.  It can't identify any triggers for these auto-tripping events.
I simply return the KPA500 to operate mode and continue the QSO
normally.  This occurs on average once per hour of operation, rarely
more frequently. 

Any ideas where to look for the cause?

Thanks and 73,

John
VK7JB

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[ke9uw]

Mine does that too...about the same as yours. I figured it was a small amount of rf getting into the data cable on occasion.

Chuck, KE9UW
Lionel Trains, TCA, LCCA, LRRC
aka Jack, BMW Motorcycles BMWMOA #224

________________________________________
From: [hidden email] [[hidden email]] on behalf of [hidden email] [[hidden email]]
Sent: Wednesday, January 23, 2013 6:38 AM
To: Elecraft Group
Subject: [Elecraft] KPA500:  strange behaviour - any ideas?

Hello Group,

I'm running KPA500 #1076 with firmware 1.23 installed.  It's
connected to my K3 via the elecraft AUX cable and is connected to my
PC via serial to USB adapter cable using FTDI chipset.  Interfacing
functions with the PC and K3 work flawlessly.

It runs perfectly apart from one intermittent peculiarity:
unpredictably, when in QSO, the amp will switch from operate to
standby mode.  This does not trigger the Fault indicator and no fault
# is ever reported by the KPA500 to the utility program or to the K3
LCD.  It can't identify any triggers for these auto-tripping events.
I simply return the KPA500 to operate mode and continue the QSO
normally.  This occurs on average once per hour of operation, rarely
more frequently.

Any ideas where to look for the cause?

Thanks and 73,

John
VK7JB

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[Gary Gregory-2]

I only see this rarely when I use my open wire antenna. The amp does not do
this on my standard dipole fed by coax using a choke.

I have always assumed it was RF but that is only a thought, I have not been
able to prove it as yet.

Regards
Gary

On 24 January 2013 00:21, hawley, charles j jr <[hidden email]>wrote:

> Mine does that too...about the same as yours. I figured it was a small
> amount of rf getting into the data cable on occasion.
>
> Chuck, KE9UW
> Lionel Trains, TCA, LCCA, LRRC
> aka Jack, BMW Motorcycles BMWMOA #224
>
> ________________________________________
> From: [hidden email] [[hidden email]]
> on behalf of [hidden email] [[hidden email]]
> Sent: Wednesday, January 23, 2013 6:38 AM
> To: Elecraft Group
> Subject: [Elecraft] I:  strange behaviour - any ideas?
>
> Hello Group,
>
> I'm running KPA500 #1076 with firmware 1.23 installed.  It's
> connected to my K3 via the elecraft AUX cable and is connected to my
> PC via serial to USB adapter cable using FTDI chipset.  Interfacing
> functions with the PC and K3 work flawlessly.
>
> It runs perfectly apart from one intermittent peculiarity:
> unpredictably, when in QSO, the amp will switch from operate to
> standby mode.  This does not trigger the Fault indicator and no fault
> # is ever reported by the KPA500 to the utility program or to the K3
> LCD.  It can't identify any triggers for these auto-tripping events.
> I simply return the KPA500 to operate mode and continue the QSO
> normally.  This occurs on average once per hour of operation, rarely
> more frequently.
>
> Any ideas where to look for the cause?
>
> Thanks and 73,
>
> John
> VK7JB
>
> ______________________________________________________________
> 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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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>

--
*Gary - VK1ZZ
Motorhome Portable
The Shack*
*Elecraft K3
P3 Panadapter
KPA500FT
KAT500FT**
KX3-K
*
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[WM3M]

KPA500 and K3 set up does this also.
I have tried to duplicate it without much success, it is somewhat random.
What I think the cause is, the output power of the K3 exceeds what the
KPA500 wants, even though I have set it per band, I think sometimes there is
a spike in power, causing the KPA500 to fault.
This is a guess on my part, since if I cut back on the power on the K3 it
does not do it as much.
The other thing I have noticed,  it does it more on certain antennas, so it
could be related to SWR.
I have the KAT500 too and SWR is checked before I transmit with the KPA500.
I tend to transmit on the same freqs a lot.  Some days it will work
flawlessly, then the next day, with nothing changed, the KPA500 will have
this problem.
Please advise if anyone figures this one out.   Thanks
Emory  WM3M



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[Ignacy]

I find this in KX3 with kxat3. Retune works. Replacement of KXAT3 did not help.
Ignacy

[VK7JB]

Hi All,

Just to close the loop, a note to say that I found the cause of this intermittent issue: I removed the adapter cable between the PC and the KPA500 and the issue has not recurred after many hours of use. I suspect it related to some RF getting in to the control circuits of the amp via the cable, as one poster suggested. Thanks to everyone for the replies and ideas.

73,
John
VK7JB

>
> I'm running KPA500 #1076 with firmware 1.23 installed.  It's connected to my K3 via the elecraft AUX cable and is connected to my PC via serial to USB adapter cable using FTDI chipset.  Interfacing functions with the PC and K3 work flawlessly.
>
> It runs perfectly apart from one intermittent peculiarity:  unpredictably, when in QSO, the amp will switch from operate to standby mode.  This does not trigger the Fault indicator and no fault # is ever reported by the KPA500 to the utility program or to the K3 LCD.  It can't identify any triggers for these auto-tripping events. I simply return the KPA500 to operate mode and continue the QSO normally.  This occurs on average once per hour of operation, rarely
>
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