I was reading the Elecraft reflector and followed a pointer to the Air Force
MARS website where they have a list of what radios are MARS-compliant and
what ones aren't. No Ten-Tec amateur rig is listed as compliant due to
insufficient frequency stability. The MARS requirement is for the rig to not
drift more than 0.67 PPM, or under 7 Hz at 10 Mhz.
My Ten-Tec Omni VI/Opt1 had a severe drift problem when running high duty
modes (PSK31, MFSK). This problem was eliminated by replacing the 9.0 and
9.3 Mhz crystals on the BFO board with more stable ones from ICM. I also
installed a TXCO to replace the crystal oven (the 'lid' had become unglued).
What was once a rig that would drift down the band at least 30 Hz during a
QSO is now a rig that stays within 5 Hz of the assigned frequency. The rig
stays a lot closer to perfect alignment, also, as tested on WWV. But, there
is no ability to 'slave' the BFO oscillators to the master oscillator
(TXCO). Is this a design feature (the one that lowers phase noise)? With the
availability of 10 Mhz GPS-based frequency references, just think how stable
your Omni could be if the BFO board was slaved to the master oscillator.
The Orion's frequency stability is given as 3 PPM, and the rig comes with a
TXCO standard. I'm sure there has to be some sort of BFO mixing for SSB and
CW on the Orion, but there are no schematics in the downloadable manual. Is
it Board A5 (IFCNV)? If so (even if not), is the BFO referenced to the
master oscillator in the Orion?
How about the Jupiter?
Just curious...
- jgc
John Clifford KD7KGX
Elecraft K2 #1678 /KSB2/KIO2/KBT2/KAT2/KNB2/KAF2/KPA100
Ten-Tec Omni VI/Opt1, Centaur, 238B
Alinco DR-605TQ, DJ-V5
Icom T90A
IRLP #3978
email: kd7kgx@arrl.net
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