[INRAD] Yaesu FT-847 2.1 Khz SSB Filter

[roger sturtevant]

Charlie, Gary & others who replied to my FT847 post,

I am still working on it and I sincerely thank you for your
suggestions and ruminations.  The 1st problem of coupling
appears likely to be fixable with your suggestions of
grounding and possibly rerouting the mini-coax harness.  The
suggestion of a cold solder joint or having the 2.1KHz SSB
RX INRAD filter installed in the wrong socket do not apply. 
I installed the INRAD supplied harness and board easily,
according to instruction.  The soldering of the harness and
board by INRAD was just fine.  A Nova Scotia amateur VE1ADH
has read your mail and has reviewed the FT847 manual and
offers the suggestions below.  I have also been
experimenting with the AM setup procedure on page 58 of the
FT847 manual which sets adequate power to both sidebands.  I
believe that I may get a 'useable' AM transmission with
Dave's suggestion. 

Next Sunday, I will attempt to experiment with these
settings on a weekly AM Net and ask the participants for
comment.  Several replies will be helpful to eliminate the
possibility of atmospheric causes of phase distortion which
may not be related to the modified rig causes which are also
evident. Thank you all for your comments so far.  I still am
most concerned about the AM TX problem, even though the
"coupling" is also an unwanted byproduct of a good SSB RX
filter.

VE1ADH's comments follow for the list's information:

"I believe I am starting to understand what exactly is
happening. From your comments re how the manual says to
setup for AM I believe Yeasu has come up with an ALC system
that works well on AM. ALC detects power out and reduces
drive to prevent overdriving. It works very well on SSB but
on AM it tends to cause the carrier level to change in a way
that is not good for true amplitude modulation. Since Yeasu
says to setup on AM for 33% as opposed to 25% like most 100
watt SSB rigs, I think they have developed an ALC system
that gets around that problem. It is intended to work with
the original filter setup however, and not with the narrower
filter. With the narrow filter less rf enegry is being
detected at the output so the ALC action is 
reduced.

You may have to disregard the manual setting procedure and
set it up to only 25% i.e. 25 watts. Another way would be
try and switch filters some way as I suggested this morning.
If you could switch back to the original filter setup in AM
and to the new one in SSB you could have the best of both
worlds. If you think this may be an idea you would want to
pursue let me know and I would be glad to 
help in any way I can.

73, Dave" 

 
*******************************************************************



>   I sent my reply direct and never heard back as to
> whether my  suggestion was a cure to what ailed your
> FT-847.  Charlie  W5VIN
> 
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