KAT2 C55 null

[Chuck Teague]

I'm installing the KAT2 and am having trouble getting C55 to null (as so many have.)  I've rewound T1, checked for solder bridges, errors in component placement, orientation or value and every thing else I can find to try from gleaning these archives.  The only anomaly I can find so far is that pin 7 of U4 has 4.6 volts on it rather than zero.  Pin 7 isn't used, but does the fact that voltage appears there indicate U4 is shorted?

Voltage measurements were taken with the control board and LC board separated, and only J8 connected to the K2.

One more question.  I will be installing the 100 watt amplifier and KAT100 in a separate enclosure for later use.  I understand that R6 on the KAT2 control board needs to be changed to 470 ohms for that operation; should I just do that now?

Thanks to the group,

Chuck NN7U

[Chuck Teague]

I somehow lost two emails to the ether so I can't do a direct reply, but thanks for the response.  Yes, I'm sure it's pin 7 that has the 4.6 volts on it.  Pin 8 has the expected 6 volts, and all the other voltages listed in the manual check out.

NN7U

[Chuck Teague]

Got it.  Thanks to  Doug, W4DAS, Gary Surrency at Elecraft and my trusty magnifying glass everything is working well.

Chuck
NN7U

[AF6NI]

Looks like the replies were directly to you so they don't show on the list. What turned out to be the trouble?

[Chuck Teague]

Operator error(s).  A relay in backwards, and a solder bridge that I cleaned up too well, removing the trace beneath it.  Replaced the solder bridge and all was well.

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From: AF6NI [via Elecraft] [mailto:[hidden email]]
Sent: Thursday, July 19, 2012 6:28 PM
To: Chuck Teague
Subject: Re: KAT2 C55 null

Looks like the replies were directly to you so they don't show on the list. What turned out to be the trouble?

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