[Amps] TL-922 buzzing noise

[Szegedy]

Dear Friends!

Please help me.
I have a TL-922.I noticed that if I switch my amplifier from CW to SSB mode,I can hear a buzzing noise from the left side of the amplifier,but in CW is ok.In transmit much more noise comes from the left side of the amplifier.
What is this buzzing?But linear works .What  Can I check? Something wrong? Can I use the linear or will it be a problem?

                                                                                           Thanks:Laszlo HA5BZR