Ward,
From your numbers, it does not seem that you have any excessive loss through
the xtal filter.
First, check soldering, then check soldering, and when you have completed
that, check the soldering. That is the most common cause of problems.
It may simply be that your BFO frequencies are not correct. The values in
the KSB2 manual are only starting points - if your manual is older (for the
2.0 kHz bandwidth), and you have installed the capacitors for the 2.2 (2.3)
or 2.5 kHz bandwidth, you can expect that the initial BFO frequencies will
not be correct. Check out my website www.qsl.net/w3fpr article on K2 Dial
Calibration for the long story - or skip right to that article's Step 3 -
CAL FIL for details on how to properly align the BFOs to give you the proper
demodulated audio range.
73,
Don W3FPR
----- Original Message -----
I'm still trying to figure out why signals drop when I switch in OPT1 on
my newly-built SSB board for my K2/100. The static goes way down, but do
do the voices!
Last weekend I discovered rfc2 shorting out to they can of crystal X7.
When I rewound it that helped some.
Today I rewound T2 and that didn't make any difference at all.
I've been around once with Gary, and I think all the obvious things are
right. The crystal cans aren't shorted to ground, the caps are the right
values and aren't shorted by DC either, the diodes are in the right way
and the voltage checks on the switching network are fine.
Gary says there should be a "small but progressive" signal loss through
the SSB filter. To check this, I tuned to the birdie at the bottom of 40
meters, and dragged out the scope.
I set in on a 2mv scale with a 1ms sweep (slow) and used the measuring
cursors to take an average amplitude. I did AC coupling with a 1X probe
(so may have been loading things down some). Then I shoved a 3 inch
leftover component lead into the probe clip so I could poke around in the
small places.
Here are the numbers, from input to output:
P2 -> T1(2) -> T2(4) -> X1 == ~ 1.75mv
before X2 1.28mv
before X3 1.28mv
before X4 1.28mv
before X5 1.28mv
before X6 1.20mv
before X7 1.20mv
T2(3) 1.20mv
T2(1) --> all the way out to P3 ~1.68mv
I can go around again with Gary -- but before the weekend goes and before
I tear too much working stuff up, thought I'd throw it out to you guys to
see if there is anything obviously wrong with these numbers or the way I
acquired them.
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