Werner,
Part of those modifications is the KI6WX KSB2 Increased RF Gain Mod.
That mod worked fine with the QRP K2, but after the KPA100 was out for a
while, some folks noticed that they had the same problem that you
describe when the mod was installed.
The problem is that the ALC circuits on the KSB2 board are being
overdriven. Add the following changes:
On the KSB2 board, 1) change R9 to 1.5k; 2) break the path from KSB2
board P1 pin 6 to the base of Q1 and insert a 1k resistor from P1-6 to
the Q1 base.
Those additions should calm the behavior down to normal.
73,
Don W3FPR
Dr. Werner Furlan wrote:
hello to the group,
since the beginning of my tests with the KPA100 I am observing a strange
problem.
On 80 and 40m I must not use a Comp setting > 1 (which is off) otherwise
the output jumps to 150W (measured with the LP100 meter)
In CW mode and when I turn Comp off everything is in the normal range.
When I turn the RF power below 10 Watts everything looks fine.
Today I visited my friend OE9FSI and we found out, that he has exactly the
same problem but he never noticed it because he rarely works on SSB and
always had Comp off.
We both have made the SSB modifications to increase mic gain and comp
as described here.
http://www.qrpproject.de/Media/pdf/ZusammenfassungMods.pdf
I have read on the list a note from Don Wilhelm about a problem that seems
related to me which has to do with a R98 value not being adequate for my
K2, but I am not sure if this is the right trace to solve the problem.
Your help would be very appreciated.
73! de Werner OE9FWV
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