Raimon,
I do believe your first checks should be on the KSB2 option board.
Look at the schematic for the KSB2 in the lower left corner area - you
will find several passive components associated with Q1, D1 and D2 -
those are the components are in the SSB ALC section and are the ones to
check.
I would look first for a poor solder connection. It is not uncommon for
a marginal solder connection to fail after a few years even if it worked
fine initially - once an oxide coating develops, it will fail (usually
because of a higher than normal resistance at the connection). It
*could* be a component failure, but I would check the soldering first
and re-flow it if there is any question at all about its current quality.
I tend to believe that the band dependency is a 'red herring' and is the
simple result of the fact that the intrinsic transmit chain gain of the
K2/100 goes down as the frequency is increased.
If you find no problem obvious on the KSB2 board, I would suggest that
you remove the KPA100 and test the base K2 for a similar condition.
73,
Don W3FPR
raimon wrote:
Hi all
I am having troubles with my K2, and need your help.
My K2 is nr. 3529, with K2/100, KAT 100 and KSB2SSB
It has been working fine until now, mainly CW and BPSK31
Now it continues to work all right in CW in all bands, but in SSB
power output drops substantiably in 20, 30, 15 ,12 and 10 meters bands.
As an example, readings of output power in 14070 are:
CW 80 w
SSB L 50 w
SSB U 20 w
SSB r inv. 20 w
Readings made with K2 connected to a dummy load trhough a Kenwood
AT230, power setting in K2 100 w., injecting a 1000 Hz tune signal
from MultiPSK programm. (same problem with a microphone)
No problems in bands 80, 40 and 30 (80 w. Readings in all modes)
In lower bands all leds in the K2 light when transmitting, in the
other bands just 1 to 3 leds light.
I suspect the KSB2SSB module. Where should I look for the cause of
this problem?
Many thanks in advance
Raimon
EA3EZO
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
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