Problems with FT-290R SSB modulation
 

Good morning.
I hope someone has already gotten into this.

I own a Yaesu FT-290R that lately has been reported to produce a
distorted SSB modulation.

I checked with another receiver and I can unfortunately confirm that the
modulation sounds a bit warbled, fluttered, "bubbly" but still
comprehensible (say "3 by 9" RS report).

Apparently the problem worsens when the rig is operated at lower
temperatures (32F/0C or so). In low-power mode the modulation is
slightly better but still unacceptable.

FM output is OK. Output power looks fine too, at least there's an
increment between low and high levels.

Has anyone had this problem? Any cure?

Thanks,
pc

Problems with FT-290R SSB modulation
 

"PaoloC" wrote in message
...
Good morning.
I hope someone has already gotten into this.

I own a Yaesu FT-290R that lately has been reported to produce a distorted
SSB modulation.

I checked with another receiver and I can unfortunately confirm that the
modulation sounds a bit warbled, fluttered, "bubbly" but still
comprehensible (say "3 by 9" RS report).

Apparently the problem worsens when the rig is operated at lower
temperatures (32F/0C or so). In low-power mode the modulation is slightly
better but still unacceptable.

FM output is OK. Output power looks fine too, at least there's an
increment between low and high levels.

Has anyone had this problem? Any cure?

Thanks,
pc

Are you certain your P.S. is stiff enough to handle the current on voice
peaks? Sounds like it's FMing some- many times a sign of poor regulation.
Dale W4OP

Problems with FT-290R SSB modulation
 

Dale Parfitt wrote:

Thank you Dale for the input.

Are you certain your P.S. is stiff enough to handle the current on voice
peaks? Sounds like it's FMing some- many times a sign of poor regulation.

I tried with a 12V/7AH Pb-gel cell, a 12V/5Acont. and a 13.8V/25Acont.
supplies. They provide slightly higher voltages (in that order), which
reduce the effect, but not that much.

Anyway, for the FT-290R - which is a QRP 2m all-mode RTX - peak
consumption is 800mA! (per technical specs)

I doubt all my regulated power sources have gone bad altogether... will
check them anyway.

Paolo