[K3] This might save you some grief

[n7ws]

Yesterday afternoon 15-meters opened and I started to call a station only to find that I had very little transmitter power out.  Everything seemed to be set properly so I cycled the DC power and bingo I had proper output.  I chalked it up to cosmic rays (W8JI knows what I'm talking about) and went on the make the QSO. I tuned around a bit and found that 12-meters was open, found another station and started to call him and once again very little output.

I did briefly notice on the display an ERR message indicating a TX gain failure.  Going into Tune, I could only get about 40 W out while calling for 100. This varied from band to band, with the lower bands actually being worse.  So I decided to run the TX Gain calibration.  The first step on 160-meters failed at about 3.7 W.

Since I had the latest beta firmware installed, I decided to roll back a couple of versions.  No joy.  Time to take the lid off and look around.  I poked at all of the cables and the lead from the KANT3 board to the coax connector, which all seemed to be well-seated.

I contemplated removing the 100W PA, but logic said that it should be okay since it did make output more-or-less proportional to the apparent drive available.  Time to run the TX Gain cal one more time before going further.  This time it failed at 2.4 W on 1.9 MHz.  Taking the lid off and poking around had made a difference.

I won't bore you with the rest of the two hours I spent investigating this and will cut to the chase.  Removing and replacing the KANT3 board fixed the problem.  Apparently, there was a problem with the interface connector between the KANT3 board and the main r-f board.

I had a similar problem with my old TR-7 years ago.  The digital display would get intermittent and required accessing the daughter board and moving it up and down on the interface pins to scrub off the oxidation.  This would last about three or four months until I had to do it again.

I hope this isn't going to be a recurring issue with the K3.








     
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[Cookie]

Wes, I had a similar experience.  I unseated the plug at the rear of the
amplifier and reseated it.  Apparently one or more of the contacts had
corrosion.  I just reseated the plug in the socket and normal operation
returned.  I have read posts on this reflector of K3s that required the
connector to be replaced because the pins on the connector had corroded off.  I
think the newer units have gold plated pins to solve this problem.  My K3 is
number 1025.
 Willis 'Cookie' Cooke
K5EWJ




________________________________
From: Wes Stewart <[hidden email]>
To: Elecraft Reflector <[hidden email]>
Sent: Sun, September 19, 2010 1:15:49 PM
Subject: [Elecraft] [K3] This might save you some grief

Yesterday afternoon 15-meters opened and I started to call a station only to
find that I had very little transmitter power out.  Everything seemed to be set
properly so I cycled the DC power and bingo I had proper output.  I chalked it
up to cosmic rays (W8JI knows what I'm talking about) and went on the make the
QSO. I tuned around a bit and found that 12-meters was open, found another
station and started to call him and once again very little output.

I did briefly notice on the display an ERR message indicating a TX gain
failure.  Going into Tune, I could only get about 40 W out while calling for
100. This varied from band to band, with the lower bands actually being worse. 
So I decided to run the TX Gain calibration.  The first step on 160-meters
failed at about 3.7 W.

Since I had the latest beta firmware installed, I decided to roll back a couple
of versions.  No joy.  Time to take the lid off and look around.  I poked at all
of the cables and the lead from the KANT3 board to the coax connector, which all
seemed to be well-seated.

I contemplated removing the 100W PA, but logic said that it should be okay since
it did make output more-or-less proportional to the apparent drive available. 
Time to run the TX Gain cal one more time before going further.  This time it
failed at 2.4 W on 1.9 MHz.  Taking the lid off and poking around had made a
difference.

I won't bore you with the rest of the two hours I spent investigating this and
will cut to the chase.  Removing and replacing the KANT3 board fixed the
problem.  Apparently, there was a problem with the interface connector between
the KANT3 board and the main r-f board.

I had a similar problem with my old TR-7 years ago.  The digital display would
get intermittent and required accessing the daughter board and moving it up and
down on the interface pins to scrub off the oxidation.  This would last about
three or four months until I had to do it again.

I hope this isn't going to be a recurring issue with the K3.








     
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[n7ws]

I didn't touch the amplifier...this was the KANT3 board.

That said the pressure required to remove it and reseat it could have flexed something else on the main r-f board, so who knows?

Mine has been in the Elecraft hospital for another problem and had the KPA100 replaced with a Rev C, so I think it has gold pins, but until I have to open it up again for another reason, I won't know for sure.

--- On Sun, 9/19/10, WILLIS COOKE <[hidden email]> wrote:

Wes, I had a similar experience.  I unseated the plug at the rear of the amplifier and reseated it.  Apparently one or more of the contacts had corrosion.  I just reseated the plug in the socket and normal operation returned.  I have read posts on this reflector of K3s that required the connector to be replaced because the pins on the connector had corroded off.  I think the newer units have gold plated pins to solve this problem.  My K3 is number 1025.
 Willis 'Cookie' Cooke
K5EWJ

 


     
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