Hi to everyone on the list and a happy new year to all
I put a request for help up unto the list before Christmas. I had an issue
with the TX on the higher bands. On 20m and above the power dropped off
considerable. I had a couple of emails and have now had a chance to check
out the suggestion made. I have been doing some more testing. I checked
C150 but its ok
The setup is a K2 Serial 0413 with the following options fitted
KSB2
K160RX
KNB2
KAF2
K60VX
KPA100
Although the issue appeared when I had the KPA installed I removed the
KPA100 and the issue is still there. The issue is with the base radio. I
have also removed the K60VX and KSB2 to put it back to a CW only radio and
the issue persists except the on low power I am now getting very little out
on 160m but 80 through 30 is at about 8 to 10 watts which is down as I used
to get about which was about 15 watts out.
I have had a good read of the previous posts and have done some more testing
and my results are shown below.
Band
RF out
TX Current In Amps
Note
160
4.5
3
sometimes going hi-cur
80
8
2.9
60
9
2.8
40
9
2.54
30
10
2.6
20
5
2.02
17
4.5
1.9
15
4
1.78
12
3.5
1.62
10
3
1.44
I have also had a look at the control board and found that U8 pin 10 is
always at +5volts and pin 11 is at 0v at switch on but when I go to TX it
goes to +5volts and stays there on RX until I change band when it returns to
0volts.
I have also had a look at the PA transistors. Q8 gets much hotter on TX. In
fact there is very little change in the temp of Q7 compared to Q8.
Could anyone suguest where to go next.
Regards
George GI4SJQ
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