Hello Christian...
It is because your interface pulls the Mic Input at ACC 11 down. The only
way to solve that problem (with your type interface), is to unplug ACC
Connector before going back to SSB.
You will get much better results, if you use small Audio Transformers to
switch in between the Audio output (Pin 12 ACC) and the PC speaker Input of
the soundcard - and also between ModulatorInput (PIN 11 ACC) and the MIC
Input of PC-soundcard.
Please look for details at http://www.qsl.net/wm2u/psk31.html

73's from Cologne / Germany,
Klaus

"Christian Rogne" schrieb im Newsbeitrag
...
I have made an interface cable from the IC 706 to the PC. From pin 11 on
the
13 pins ACC to the speaker on the PC, and from 12 on ACC to the PC Mic. I
Also have made an easy transistor PTT switch connected to pin 3 on ACC,
and
the serial port on the PC. The problem is, when I have this connected to,
and try to make sideband operation, I got a very poor Mic Gain. Are there
someone who can help me with this problem ?

73's de LA8QJA, Christian