On my QMX (mid-band), I can hear a constant tone on some frequencies, as if someone is tuning up an antenna, but it just stays. It also doesn't make a difference if I have an antenna attached or not, so it's not an actual signal, but seems to be internal to the QMX. In a way it behaves as if it's an actual received signal, in that it shows on the S-meter. For example, on 14,074,80 I have a pretty loud one, showing 4 bars. But in another way it's not like a received signal, because when I tune slightly away from it, the tone disappears instead of changing in pitch. For example, the "signal" on 14,074,80 is completely absent on 14,074,79 and 14,074,81. I'm powering it from a battery, so it's not power supply noise.
Also, I can change the frequency of where I hear the tone by changing the CW offset. For example, when changing the CW offset from 700 to 800, the tone mentioned above moves to 14,074,90.
The tone I hear has a pitch of 820 Hz (measured with an app on my phone).
Has anyone experienced this, or know what could be causing it?
Willem VA2WLM