Hello,
I want to thank all of the help I received on this problem.
The AGC adjustment problem was solved by replacing the 8.0VDC regulator
with one that puts out 8.0 volts not 7.5 VDC..
I also had a problem where the MCU on the control board sometimes would not
start, it just froze and all controls were inop. I found an un-soldered
(surprise surprise) connection.
Not I have a new problem, and was wondering if anyone has any ideas.
As I started the alignment and test Part II. everything went fine until I
got to the 4th step on the left column on page 64. There is no output on the
left hand side of R-30.
I traced this back to U5 (I think) The voltage does not vary on pin 7 of U5
as the frequency is varied. It stays at VCC, 5 VDC. I think this changing DC
voltage must be there to make U4 and U6B operate to get the voltage on R-30.
Am I wrong on this, very little to no experience working on PLL
Synthesizers. All of the other voltages on U5 look good. Any suggestions on
where to go from here. The PLL reference oscillator is working, clean signal
at around 12.096 MHZ.
It might be a soldering problem, but I really do not think so, I have spent
a lot of time looking closely at solder joints. I will keep checking and
re-heating the solder joints.
Any suggestions on what to check would help.
Best,
DW Holtman
WB7SSN
----- Original Message -----
From: "DW Holtman" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, February 20, 2008 7:25 AM
Subject: [Elecraft] K2 Assembly Question
Hello,
I'm in the middle of building a K2, S/N 6412.
I have a couple of questions, hopefully some of the knowledgeable Elecraft
people on this forum can help.
While doing the Alignment and test Part 1, I had a couple of readings that
were not in specs.
1. Page 48, Setting the AGC Threshold, the manuals calls for adjusting
R-1 for a reading of 3.80VDC on pin 5 of U2. The highest R1 would adjust
to is 3.60VDC.
2. Page 48 Bargraph Current test. The manual calls for a current reading
of 0.16 to 0.18. My K2 reads 0.25 amps. That is quite a bit higher than
what is called for.
Any suggestions? Are these readings anything to worry about?
Thank you in advance for any help.
Best,
DW Holtman
WB7SSN
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