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[TenTec] Omni V controls and Corsair II

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Subject: [TenTec] Omni V controls and Corsair II
From: geraldj@ames.net (Dr. Gerald N. Johnson, P.E.)
Date: Tue, 29 Sep 1998 21:01:22 -0500
Frank, my solution is that I bought a Corsair II instead of an Omni V or
VI. I asked a loyal HF user of the Omni VI last night about its shifting
frequency and modes and he confirmed it does the same as the V. About
ten days ago I spent an afternoon in a shack near here that had Omni V,
Corsair II, and Cubic 103 side by side and a coax switch to put the same
antenna to each. I thought that there was a tiny bit of difference
between the V and the Corsair, probably in favor of the V, but the V's
mode and frequency shifting when changing modes turned me off. The
Corsair doesn't do that. It uses a mechanically driven PTO and also has
a varicap diode for offsets (rit/xit) but mode does not change the
frequency. It uses the N side band for CW, so where it does lower side
band it uses that for CW, but on 20 and 10 which are the bands I'll use
for transverter IFs, it does upper for both CW and SSB. The display
changes when you switch from upper to lower sideband but thats simply
because the preset frequency for the counter is changed by the 3 Khz
that the two BFO crystals are apart. I don't think it would be easy to
make it do upper ssb and cw the same mode on 80m. But for transverter
service it will be just fine.

I just carved a large aluminum knob to get more flywheel effect on the
Corsair. It ended up a third larger than the original knob and seems to
make tuning a lot more fun. My finger rolls along its poor quality
knurling with slipping. I should get it knurled properly and it will be
even better. Might not need that spinner I had planned to insert.

The RF amplifier and first IF amplifiers in the Corsair II use Ulrich
Rohde's favorite feed back circuit. Those same stages in the Omni V use
multiple grounded gate JFETs in parallel which probably works as well,
but is far easier to assemble.

73, Jerry, K0CQ

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