[TenTec] OmniVI+ 30M L.O. instability

[John Huffman]

Jack -

Sent mine back to Ten Tec and they replaced the crystal oven with a 
TCXO.  Common replacement.

73 de K1ESE
John

Jack Mandelman wrote:
> When it is very warm in my shack (~85F) my Omni VI+ has the following problem on 30M only.  
> 
> Every 35 seconds or so the frequency would jump on the order of 10-50Hz for a fraction of a second, and then return.   The symptoms suggest that the 30 meter L.O. (on L.O. mixer board) is briefly losing lock with the reference oscillator (on logic board).   At elevated temperature, I suspect that Y4 may drift slightly out of spec; the DC voltage fed back through connector 84 then corrects the oscillator frequency and regains lock.  Perhaps an adjustment of 30M oscillator coil L19 would mitigate the problem.
> 
> If the problem starts occuring more frequently I may want to slightly adjust L19 on the L.O. mixer board.  However, my question is how to access L19 while keeping the 30M oscillator active.  The L.O. mixer board is located under the FM and LL driver/NB boards, requiring disconnection of cables to access the board.
> 
> I recall some discussion on the forum a while back about a similar 30M instability problem.  I appreciate any suggestions about how to access the L.O. mixer board, while at the same time keeping the L.O. active.  I did access the L.O. mixer board to fix an earlier problem related to an L.O. output filter, but totally removed the board at that time.
> 
> 73 Jack K1VT 
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