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Old October 15th 04, 04:55 PM
chafik CN8JV
 
Posts: n/a
Default A broken SSB Filter or an Off frequency Oscillator ?

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