SB-102 CW Filter Replacement

[William C. Jones]

Thanks to all who responded to this List and to my personal e-mail regarding
my not getting the CW Filter to transmit in my SB-102.  I read and read again
the many suggestions offered before deciding what to do first.  The majority
of the replies pointed to the Filter itself , although some suggested the
crystal carrier may be off in frequency, which is certainly a viable cause.
I first started by placing small capacitors( I didn't have a small variable,
but had several 5pf and 10pf caps.) across the filter as Mr. Glen Zook
suggested.  I started with 5pf, then added 10pf, then 10pf more until I had a
total of 45pf with no change in the carrier output.  If the frequency was
high I think this would have pulled it within tolerance, if it were only
slightly off frequency.  If it were low I was out ot luck.  With a lot of
reluctance(I hate to take down radios that are operating well), I decided to
remove the CW Filter from my SB-101, which I knew was working and put it in
the SB-102.  Ah Ha, full carrier output showing on the monitor scope and
about 90watts out on the power meter of the SB-634,- in the CW position of
the filter switch on both the Tune and CW key down mode. This at least
indicated the Crystal Carrier frequency  and other circuits were operating
properly in the SB-102. While I had both radios out of their cases, I
installed the questionable filter in the SB-101 and it was the same result as
in the SB-102, very small amount of output.  This dog just would not hunt in
either radio.  I think this confirmed what the majority of the List thought,
that the CW Filter had drifted off frequency.  I then returned the filters to
their proper radios and buttoned them up.  I could still use the questionable
filter in receive.At this point I appear to have 3 choices-Try to procure
another CW Filter with what assurance it might not be off in frequency; Take
Eddy's (ve3x2) excellent solution to install a relay to switch between SSB
and CW and always transmit thru the SSB Filter; or accept the moderate
inconvenience of manually toggling the CW/SSB switch between transmit and
receive.  If this were my only radio that would not be acceptable, but
rotating operation between several radios, I guess the inconvenience becomes
more tolerable.  In my Apache/SB-300 radio combination I have to toggle
between Transmit and Standby to change antenna inputs and mute the receiver.
Your suggestions have helped to identify the problem and now I have choices
to make.  ThankYou All again for taking your valuable time, to share your
expertise and suggestions with me.  Bill,  w0fn

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