[TenTec] OMNI VI+ BFO Brainteaser

[Don Rasmussen]

Hi Guys,

As I read it from the manual, the BFO frequency for CW
is 9.000.0Mhz and that only changes when you transmit,
there is a 400hz offset to make the BFO frequency
9.000.4Mhz during the key down. 

So far so good?

I have had rare occasion (three times so far) where I
was listening on CW and the BFO seemed to pop into
transmit mode even though I did not transmit. The
signal I was listening to with the passband control at
the 12:00 position could be "found" by rotating the
PBT control to the 1:30 position. 

Switching to USB and all was normal, PBT straight up,
so I don't suspect the First or Second IF filters nor
the PCB they are on as that would affect USB too.  

As I understand it, the Tx audio board has trimmer
caps that hold the crystal to either 9.000.0(rx) or
9.000.4(tx) and they are selected by transistors and
diodes on that board. 

What I am wondering, is where the possible point of
failure might be. The problem is incidental and has
cleared up after a couple minutes but I'd really like
to know if it's more likely to be a problem on that Tx
Audio board (a crystal, trimmer, or diode, cold joint)
or with the microprocessor board that issues the
commands.

I've spoken to Ten Tec and they'd like to see the
radio
but not until I have a crack at it (hopefully not
literally!)

Any ideas?

Thanks es 73,
Don Rasmussen WB8YQJ/6
Carlsbad, Ca.


  


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