[Elecraft] K3 Tune carrier with hum

[Ulrich Quandt]

Hi,

on my K3 the tune carrier is modulated by a hum noise. If i press the tune
button i can hear this noise with an independent receiver.
It has nothing to do with my power supply and the problem appears between 1
to 100 watts.
It seems that the noise is generated inside the K3.

I have this noise only during tune, all other transmitting works flawless.

Any idea ?

73 de Uli (DL4YCM)