Our K2 was working perfectly until I opened it up, tightened the power
transistor mounting screws, realigned the receiver, and put it back
together. Now power output no longer follows the power setting. When
set to a power output less than 10W, I hear the bypass relay but I get
the High Cur display (momentarily) and the display then shows a power
output of 0.3W with an SWR of 3.0. Output power as measured with a W1
is 20W. If I advance the power control, as soon as I pass the 10W
point the PA comes on and the power jumps to 150W output. Turning the
power level control fully CCW (0.1W setting) produces 6W of output.
Looking at pin 7 of U5 on the KPA100 I can see good analog voltage
that varies with power. I can see the value of VFWD change when the
range changes (SCALE changes) also. I can also see varying VFWD at pin
2 of U1 so this does not appear to be an analog problem.
FWIW, voltages at pin 2 of U1 for various power outputs are:
6W -- 0.15V
20W -- 0.30V
150W -- 0.29V
At pin 7 of U5 (U5b):
6W -- 0.15V
20W -- 0.30V
150W -- 0.77V
On the t-r menu item I have "8r hold" set.
I do have output on VRFDET but the value only varies from about
0.3V-0.7V so that appears to be working also.
I am planning to fly to Dominica on Friday and operate from there but
I can't take the K2 unless I solve this problem.
Suggestions?
Brian Lloyd
Granite Bay Montessori School 9330 Sierra College Bl
brian AT gbmontessori DOT com Roseville, CA 95661
+1.916.367.2131 (voice) +1.791.912.8170 (fax)
PGP key ID: 12095C52A32A1B6C
PGP key fingerprint: 3B1D BA11 4913 3254 B6E0 CC09 1209 5C52 A32A 1B6C
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