R340 on the A7 board is an A to D sensitivity adjustment for the meter, as you
had surmised.
However, it acts to adjust both the S meter sensitivity (at full scale) AND the
TX power meter at 100 watts output. In fact, the only way to correctly set this
meter adjustment is to operate the radio at 100 watts into a proper 50 ohm
dummy load with an external wattmeter and set the meter in the Orion to read
the same as the external meter reads. To be fair on this adjustment, I had
asked Ten Tec the year after I got my first brand new Orion why its output
reading did not agree well with my Bird except at 100 watts. The engineer told
me that this was as good as any cared and that the power settings other than
100 watts were only “relative readings”. No effort was ever made to put a
simple calibration curve for the meter and its sensor into the radio’s firmware.
Likely what is causing your S meter zero issue when powered on is the AGC
threshold in the AGC program modes. This adjustment allows you to, in effect,
change the level at which AGC action begins to occur. In the process, the S
meter zero comes up to reflect this change as the meter now indicates the
preset ACC threshold rather than the zero signal meter reading. You can easily
correct this by setting the AGC threshold in the AGC menu to something close to
zero. It is independently adjustable for all three ACG options. Of course, you
will hear more noise as well.
Hope that helps.
Gary
W0DVN
> On Feb 9, 2017, at 2:44 AM, garyh <k4mt1950@charter.net> wrote:
>
> Th S meter zero is proper when the radio is turned off. When its on the S
> meter reads about S3 even with RF gain at 100. I noticed in the schematics a
> meter adjust pot on the A7 ADC schematic R 340. I am not sure if that would
> do the job.
>
>
> Gary K4MT
>
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