[TenTec] Omni VI Pass Band Tuning CW Narrow

[John Huffman]

I have a new-to-me Omni VI+.  I have a question concerning pass band tuning and the filters.

My Omni VI+ has these filters:
9MHZ
(48058) 9429 8-pole -2.4 khz
N1
(48058) 9918 8-pole -2.4 hz
N2
219 (48055) 6-pole -250 hz

6.3 MHZ
282 (49054) 6-pole -250 hz-
285 (48053) 6-pole -500 hz-
288 (48075) 8-pole -1.8 khz-
Standard - 2.4 khz

I view my audio output using Spectrogram (wonderful for zero beating for those of us with 
a tin ear).  Using Spectrogram you can see the range of audio frequencies being sent to 
the headphones and speaker.

When I turn the PBT knob, I can see the passband shift up or down for each filter except 
the 219 (48055) 6-pole -250 hz in position N2.  That filter doesn't move.

If the knob on the PBT is centered it shows passing a narrow band of frequencies (although 
not as cleanly as the other filters).  If I turn the knob fully CCW there is no change in 
the frequencies or width.  If I turn the knob CW, the audio fades and disappears as The 
knob is turned.

Is this normal?  The filter in the N1 position behaves as expected.

73 de K1ESE
John