[TenTec] Omni VI Opt 1 - Strange tone

[Darrell W4CX]

Gents...well now that I can do some easy A/B comparisons between my Omni VI
Opt 1 and other rigs, I've come across a nagging problem with the Omni.  Not
sure whether its been there all along or if I just noticed it:  With no
antenna connected (or even into a dummy load), I'm hearing a hollow tone
about 1Khz that doesn't change by tunining (i.e not a birdie).  S meter
hovers around 2.5. Turning off AGC produces a clean sine tone.  Interesting
that changing IF filters changes the frequency of the tone, and, most
important, if I back off the RF Gain by one unit (dot), the tone goes away
and the RX sounds "normal".   Anybody ever seen this symptom before?  73,
Darrell W4CX  Raleigh, NC.