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RE: [TenTec] TXCO unit

To: <tentec@contesting.com>
Subject: RE: [TenTec] TXCO unit
From: "John Clifford" <johnclif@ix.netcom.com>
Reply-to: johnclif@ix.netcom.com, tentec@contesting.com
Date: Wed, 3 Nov 2004 22:39:21 -0800
List-post: <mailto:tentec@contesting.com>
The BFO oscillators don't drift on receive, but try transmitting for a
minute or two using a full duty-cycle mode (like PSK) and watch your rig
drift. Sure, it's within Ten-Tec specs and you'll never notice it for CW or
SSB (because it doesn't happen) or RTTY (because it doesn't matter), but it
is an annoyance on PSK and a problem with tight-tuning modes like MFSK16.
You'll find yourself walking down the band by 30 Hz or so with every PSK
transmission, and you will have to manually re-tune after every MFSK

The solution is to upgrade your VI with ICM replacement crystals that will
hold to within 25 Hz (mine do considerably better than that). They cost more
than the Ten-Tec ones (but not much more) and the rig is MUCH more stable
with them.  

I think the TXCO and BFO xtal upgrade makes a good rig much better. Of
course, the ultimate would be to redesign the BFO board so they used the
master oscillator... and then replace the TXCO with a 10 Mhz external
GPS-based reference.

Someone with a Jupiter and an Orion, please jump in and tell us if these
rigs use one master frequency reference or do they also have separate (and
non-referenced) BFO xtals.

 - 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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