Oscillator Bleed Through??

[2E0JFS]

Sorry all,
So many questions.

I have noticed on higher frequencies the VCO from my TX Radio in this rig (my G90) is to the side of the listening frequency on 20m and up.
Tuning to a higher frequency is inaudible, however as you tune down the frequencies and the radio lags slightly in the omnirig sync - you hear the tone.
on 21mhz particularly the tone has a far amount of energy behind it.

It doesn't seem to be audible in static RX - or really interfere with the operations, rather more than just annoying birdy hi ..hi ...

If I shut the rig down its gone. I did think that the SDRSwitch (SDRSwitch.com) would be good if it grounded the TX Radio when PTT was open ??

Has anyone any experience getting rid of this effect without is reducing RX performance?