[TenTec] GPS and Ten Tec Rigs

[John Clifford]

Several people have replied that the overall frequency stability of the Omni
VI/VI+ depends upon the crystals on the Local Oscillator board.  However,
according to the circuit description of that board, part of the derived
crystal oscillator signal is used to provide feedback via the Logic board so
the signal is adjusted to be at the 'right' frequency based upon a reference
frequency back at the Logic board.  Looking at the Logic board circuit
description and schematic, it appears that the 10 Mhz signal provided by the
xtal oven/TXCO is used by Q1 and Q2 to provide the 20 Mhz signal which is
divided back down to 10 Mhz and used as the reference frequency.  So...
doesn't this 10 Mhz signal essentially control the generated band-specific
frequency on the L.O. board, and as long as the frequency emitted by the
particular L.O. crystal is close enough to be pushed or pulled to the
correct frequency via feedback from the Logic board, then the 10 Mhz
reference frequency does in fact control the rig?

This excepts the BFO crystals, which I have found to be a source of
frequency drift during transmit (within Ten-Tec specs, but still excessive
for the various HF digital modes), hence the substitution of
better-tolerance crystals.

I'm sure you guys know more about electronics than I do... heck the clerk at
Radio Shack probably knows more about electronics than I do... so more
education would be appreciated.  Is my assertion in the first paragraph
correct?

 - jgc

John Clifford KD7KGX

Heathkit HW-9 WARC/HFT-9/HM-9
Elecraft K2 #1678 /KSB2/KIO2/KBT2/KAT2/KNB2/KAF2/KPA100
Ten-Tec Omni VI/Opt1
Alinco DR-605TQ
Icom T90A

email: kd7kgx at arrl.net