True about the trouble on 18MHz. My Omni-C was putting out a watt to 1.5
watts KEY UP. There were multiple birdies -- some moved with tuning, others
were stationary. I called Ten-Tec and spoke with Garland Jenkins about the
trouble. He said the only cure was a new rig -- that 18MHz was the big
reason Ten-Tec went to the different mixing scheme.
73, Mike N4NT
----- Original Message -----
From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
To: <tentec@contesting.com>
Sent: Wednesday, September 17, 2008 5:38 PM
Subject: Re: [TenTec] 546c advice
On Wed, 2008-09-17 at 21:21 +0000, jones_winston@bellsouth.net wrote:
I also once owned an Omni A (analog) and the later Omni C. Both are great
rigs.
However, there was a design problem in the Omni C on 17 meters that was
due to the conversion scheme used. I've heard it explained better by
some engineer-type hams than I can do. I understand it caused spurs to be
transmitted.
17 Meters is 18 MHz. The IF is 9 MHz. The mixing scheme in that vintage
Omni mixed the PTO to 9 MHz. Mixers put out lots of second harmonic,
especially from the LO input. It probably was stronger than the mixed
signal. Hence a continuous transmitter spur. Also should show up on
receive when tuned to 18.0 MHz.
73,
Winston K4CWQ
73, Jerry, K0CQ
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