HDG6112B generator - FM modulation issue

Oldino

Hello

I'm using one of Hantek product: HDG6112B arbitrary function generator. During some tests I found a firmware error concerning FM modulation: if carrier waveform frequency is low (kHz) everything works great. But if carrier waveform frequency is tens of MHz there is no FM modulation for lowest deviations. Only is You set wider deviation - modulation apperar with huge distortion. This threshold depends on carrier waveform frequency - eg. for carrier 27MHz distorted modulation appear above about 1700Hz of deviation. For 87MHz carrier distorted modulation appear above about 5300Hz of deviation.
Please check it by Yourself. I have latest firmware - 2.0.0.1(201219.0). This issue occurs in both channels and every modulation source. Anyone else find this issue? Hantek should remove this problem in next firmware...

Regards