[TenTec] Omni VI+: low TX and RX on 12 meters

[MadScientist]

Before you risk alignment, you can try my spare board.

Gary

> On Dec 29, 2018, at 2:40 PM, Phil Erickson <phil.erickson at gmail.com> wrote:
> 
> Hi all,
> 
>  More investigation has narrowed the problem to the BPF/front end board
> 81593.  We'll use 15 and 10 meters as our "working normally" and 12 meters
> as "working abnormally" for this discussion:
> 
> - LO input from the XO-LO board at connector 26 is at exactly the right
> appropriate frequency for a 9 MHz IF, and nearly constant voltage for
> 15/12/10 meters.  That eliminates the XO-LO board as the problem (relief!).
> - TX input at connector 27 is also nearly identical on 15/12/10 meters.
> - However, the output at connector 24, which goes off to the low level
> driver board, is not the same for all three.
> 
> Using a 1 Mohm input impedance on a Tek 2465A scope:
> 
> 15, 10 meters:  in TUNE mode, signal increases with PWR knob up to
> about +/- 2V at three dots up from minimum (10:30 am clock position) and
> then essentially saturates
> 12 meters: in TUNE mode, signal increases with PWR knob but only up to
> about +/- 0.12V at three dots up from minimum and then essentially saturates
> 
>  Not sure why the signal is saturating at the 10:30 am position as I would
> have figured it would go up as I turned PWR up further.  (It does go up to
> a clean 90 watts or so on 15 and 12 meters when everything is hooked back
> together.)  No matter; the problem is clearly in low output at 12 meters
> from 81593.
> 
>  Since 81593 has individual BPFs for each band that are used for both TX
> and RX, my guess is that the BPF is off frequency for 12 meters which would
> explain why I have a relatively deaf receiver by 20 dB on that band as well
> as low TX output.
> 
>  Now the next question to this group: does anyone have the alignment
> procedure for a 81593 BPF/front end board?  The manual does not describe
> one.  I am also very careful about adjusting slugs as like many of you,
> I've had inductor cores snap in two with too much pressure, so I want to do
> the minimal amount of tweaking to fix the problem and not do too much
> "golden screwdriver" wiggling back and forth.  Knowing what to inject and
> where to inject it would be great.  (I have HP signal generators and the
> like available.)
> 
>  This list is really terrific - and thanks to Gary W0DVN and Pete in
> particular!
> 
> 73
> Phil W1PJE
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