expensive! The 10 MHz GPS stabilized part is a no-brainer and
the parts are
cheap and available. It's the rest that's a challenge.
I am using an HP 58540A GPS-disciplined OCXO with another brand of
transceiver. Of course, stability is excellent but even the best GPS-based
OCXOs are phase-noise-limited to about -145 dBc @ 1kHz. Not bad, but not
great.
For use on general coverage rigs, the performance is probably acceptable. On
the Orions, I suspect that these units will become a limiting performance
factor. However, Jackson Labs has recently introduced a low-noise
GPS-Disciplined OCXO with phase noise performance about 10 dB better than
that of the HP units:
http://www.jackson-labs.com/docs/Fury_Flyer.pdf
Probably a better solution for Orion owners who demand exceptional accuracy
and noise performance is to consider retrofitting a high-stability OCXO with
an SC cut:
http://www.wenzel.com/datasheets/streamline/501-04608.htm
Note that specified phase noise at 1 kHz from carrier is down about -165 dBc
with the Wenzel OCXO. Although they're not GPS-locked, stability is so good
that they need no ongoing locking mechanism. It's been a while since I've
checked on pricing, but none of these options are cheap. Plan on spending ~
$200-$300 USD or even more for any good OCXO.
Paul, W9AC
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