Hello
I have an IC-706 MKII, works fine on all modes except SSB:
On receive,I look at the audio spectrum analyser software, I have
found the following:
in LSB mode, most of the BF energy is located
between 1200 Hz and 2800 Hz approximativly.
in USB mode, most of the BF energy is located
between 200Hz and 1800 Hz approximatively
Fortunatly I can fix the problem by turning the IF shift knob about
-500 Hz in order
to have a normal audio quality.
(NB: the IF shift knob shifts the first oscillator and the BFO by
+-1200 Hz )
But the problem is getting worst while Transmitting since the other
station receive only the lower frequencies of my voice in USB mode,On
LSB mode
the other station receive only the Higher Frequencies of my voice
which give
a hard to copy modulation. the IF shift is not available on Transmit.
On other hand,the output power is only about 30 % on LSB and 70 % on
USB.

So, I dont know if the SSB filter is broken or that the some
oscillator is
off frequency by 500 Hz.
In the Service Manua, I did not found any way to play whith the
oscillator
or the BFO frequency.
Any Idea please.
73 CN8JV Chafik
Morocco

It seems to me that the unit simply needs alignment. Get a service manual
and go through the alignment step by step. You will need a frequency
counter, oscilloscope, and some other gear as listed in the manual.
Otherwise, find a friend with this stuff and that should fix it. I don't
think the filter is the problem. The oscillators have to be set.

73, Bob

So, I dont know if the SSB filter is broken or that the some
oscillator is
off frequency by 500 Hz.
In the Service Manua, I did not found any way to play whith the
oscillator
or the BFO frequency.

Chafik-

I have the older IC-706, which is most likely uses the same IF scheme as yours.
My first impression is that the most likely problem is a bad IF Filter.

While older equipment had separately adjustable USB, LSB and CW crystals that
were warped by the IF-Shift control, the IC-706 apparently gets its IF
converter frequency from a synthesizer that is controlled by the CPU. I don't
know how it is warped. It might be done digitally. If it is done by warping
the master oscillator, there is a possibility it is misadjusted, except I never
found such an IF adjustment procedure in the service manual.

If you happened to have one of the optional filters (or could borrow one), you
could see whether the problem follows the filter or the IF-Shift.

73, Fred, K4DII