[TenTec] TT Synthesizer Accuracy (Omni VII)

[demerson]

     I have checked my Omni VII receiver against all available WWV and 
CHU frequencies between 2.5 and 25 MHz.. The frequency error of the Omni 
VII is within spec, but I believe could be reduced. Plotting the 
frequency errors against frequency, there is an excellent straight line. 
The slope of this line can be reduced by adjusting the internal 20 MHz 
frequency standard in the Omni VII, as expected.  However, besides the 
slope of the error vs. frequency line, there is a constant and stable 
zero offset of some 4 Hz on the frequency error plot, which is 
independent of receiver frequency and which cannot be removed by 
adjusting the 20 MHz standard.

   There must be some other oscillator within the Omni VII responsible 
for this small offset - perhaps even the A/D converter clock. Does 
anyone know what other oscillator there is in the Omni VII that is not 
locked to the internal 20 MHz standard?  Is it possible to adjust it? 
Although my Omni VII frequencies are within spec, I am still curious.
                 Thanks,
                     73
                         Darrel, aa7fv.