[Elecraft] KPA500 problem

[Mike Crownover]

Mark,

Menu is set to K3

I've configured the amp 2 different ways, Key Out  to PA Key, with 2
different cables....no difference

KPA500 AUX from K3 to KPA 500, with a known good cable, ( I have a K3 line
already) and the one that came with it....no difference. The band changes
all work fine.

I'm certainly not a technical guy, but it seems to me the transfer from
radio to amp to key the amp is working fine. There is something after key
down that is shorting or somehow malfunctioning that shuts the amp down. I
can turn the power on the K3 down to 10 watts and tap the paddle and the amp
works, but put two dits in a row and it shuts down.

I've inspected the inside for transformer damage and there is nothing
visible. The one lead that Elecraft gave me was that the screws for the tilt
bar were installed backwards, leading to the possibility of a short with the
transformer. I had to remove the transformer to reverse those screws, (they
sent me the procedure), but that wasn't the problem either. 

I didn't use a configuration that would require the interrupter.

Thanks for your comments and thoughts.

73,

Mike AD5A



-----Original Message-----
From: Mark E. Musick [mailto:markmusick at sbcglobal.net] 
Sent: Tuesday, February 16, 2016 1:11 AM
To: 'Mike Crownover' <ad5a at gvtc.com>
Subject: RE: [Elecraft] KPA500 problem

Mike,
First connect the amp to a dummy load and see how it behaves. This
eliminates the antenna. Yes, I know the SWR is 1:1, but it eliminates it as
a possible problem and you are not putting a signal on the air causing QRM.

Go into the KPA500 menu and make sure RADIO is set to K3.

Are you using the key out of the K3 to the key in (PA KEY) on the amp for
keying the amp or are you keying the amp through the cable connected to the
K3 accessory socket? If you are using key out to key in, did you put the
keying interrupter for pin 11 on the K3 accessory jack? 

Try the basic cabling setup as described in the manual.
Just connect RF IN from the K3, RF OUT to the dummy load, KEY OUT on the K3
to PA KEY on the KPA500. Leave the cable from the K3 accessory socket to the
KPA500 AUX socket disconnected. See if it operates in this configuration.

Let us know the results.

Mark Musick, WB9CIF


-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Mike
Crownover
Sent: Tuesday, February 16, 2016 4:12 AM
To: elecraft at mailman.qth.net
Subject: [Elecraft] KPA500 problem

I just bought a lightly used KPA500. It arrived from the seller, well packed
and complete with cables, manuals, etc. I turned the amp on, interfaced it
with my K3, keyed the radio and the KPA500 immediately shut-off. No fault
light or error code, nothing. It shuts down just as if I had pressed the
power button, the fan runs, etc... The antenna is resonant 1:1, I've lowered
input power to 10 watts, swapped coax, hooked it up to another K3, used RCA
to RCA cable, the Elecraft cable, etc.. When down to 10 watts input, I can
tap the paddle like a straight key lightly and the amp works, but put two
dits together and it shuts down.

 

Has anyone had an experienced anything like this. I keep thinking this has
to be something simple.

 

Mike AD5A

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