[ICOM] IC-751A background noise

[Hank -SM2YSW]

Hello!
No1:
I have a 751A with "background" noise from the speaker(or headphones),when
I turn off volume to sero,
or in TX mode,there is a sort off buzzing sound that shanges when I turn
the VFO,or if  I use some funktion that shanges the display text..
No2:
When in TX,my modulation is different in USB/LSB ,have done the BFO and PBT
adjustments,but still there is some differens in my voice..

Any clue?

--73's  -Hank-