On Wed, 19 Jul 2006, R. Torsten Clay wrote:
In the process of calibrating my LP100 wattmeter, I was hopping back and
forth between bands and transmitting. I discovered a strange problem with my
K2/100 #3134. This is what happens:
First, I have the K2 hooked up to a dummy load. I also confirmed that this
happens with a different wattmeter in line. I am keying the K2 with a
straight key.
1. I transmit on 28 MHz. I get about 100w out.
I press "band -" several times until I get to 1.8 MHz. Putting the
key down, I get about 110 w out as expected.
2. I transmit on 28 MHz. I get about 100w out.
I press "band +" once to get to 1.8 MHz. Putting the key down, I get
170 w out !!!
In other words, it makes a difference whether I go from 10m to 160m either by
pressing Band - several times, or Band + once. Pressing Band + once somehow
screws up the tx agc. The problem does not seem to be in the KPA100, because
if I turn the power down to 10W I get similar response (10W one way, 15W the
other way).
I still don't know why it was doing this. Re-aligning the whole rig did
not help. However, after increasing R98 to 680 Ohms I no longer get 160W
on 160m.
BTW I also tried to fix the low power on 10M. I rewound T4, T2, adjusted
the output filters, fiddled with T1, and peaked very carefully. In the end
I gained maybe 1 W, now 8W max on 10M (without KPA100).
Torsten
N4OGW
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