[Yaesu] FT847 Raspy SSB

[Eric Lemmon]

Steve,

If you read many of the postings on this list from a few years ago,
you'll see that early production models had RF intrusion problems
stemming from circuit boards that were poorly grounded.  While some
FT-847 owners tightened the screws holding the boards to the chassis,
fixing the problem themselves, others took advantage of a free factory
repair.

Before you make external changes, call Yaesu to see if there is a fix
for your particular serial number.  I have a year-old FT-847 that has
none of the problems you describe, because the factory incorporated the
changes that prevented them.  In addition to improving the board
grounding, Yaesu added a few bypass caps and changed a few values here
and there.  The FT-847 is a very good radio, and Yaesu should make yours
work properly!

73, Eric Lemmon WB6FLY

"Steve L." wrote:
> 
> Hey, anybody fight the battle of RF in their mic yet?
> 
> I've had this problem since my rig was new, severe
> distortion of the SSB transmit if there is ANY RF in
> the area. It's a real killer on FD and remote VHF
> stuff.
> 
> Gotta drop the TX power to 25W to completely eliminate
> it, doesn't depend on mic gain or processor at all.
> Gets even worse with different mics!
> 
> My other rigs work perfectly in the same setting, even
> with the same microphone, even at 1500W. Tried all the
> usual grounding changes, ferrite chokes on the mic
> cable, DC power cord and coax with zero results. Gets
> worse and better depending on how close you are to the
> antenna, still does it with an antenna 150W away
> running barefoot and a well decoupled transmission
> line.
> 
> My next try will be to bypass the mic signal to GND w/
> a 2200pF cap inside the rig. Then, back to Yaesu for
> their stab at it but it's been my previous experience
> the factory will TX into a dummy load and say it works
> great.... not with Yaesu, never had any of them fixed
> before.
> 
> 73, Steve N4SL
> 
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