Thanks to everyone who gave me suggestions about how to troubleshoot
this problem. It has now been solved, and the solution was not as
esoteric as one might have imagined. I had a friend, who has built a
number of Elecraft kits, look over my KAT2. He discovered that I had
left out R3! Now, once that resistor was in place the readings nulled
appropriately. Why I left that resistor out during construction I have
no idea. It took another set of eyes to discover my omission. The KAT2
is now calibrated and working quite well. Again, thanks to all who
offered help. This is a great list with great people!
73,
Carl
N8VZ
k4zm wrote:
I've built the KAT2 and have become "stuck" at the Bull Bridge
Adjustment stage (P. 16 Rev. D Manual). No matter where I place the
trim capacitor C55, I get "Hi" on the screen when I do a Tune in CALn
mode.
Carl:
I usually make this adjustment using an old analog voltmeter on the
lowest dc votage scale. You can see the null much easier. I connect
the meter negative lead to ground and the postive meter lead to pin 4
of U1. Then follow the directions in the manual. If it will not null
then you probably have a problem with T1. I would guess that 95% of
the problems with a null function are caused by T1 problems. (poorly
tinned transformer leads, the omission of the link between pins 5 & 6
of T1 and the leads of T1 not installed in the correct holes in the
board)
73
Jim Younce K4ZM
K2 SN: 18
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