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Re: [TenTec] New Rig....

To: tentec@contesting.com
Subject: Re: [TenTec] New Rig....
From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Reply-to: geraldj@storm.weather.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Wed, 09 Jul 2008 10:47:14 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
On Wed, 2008-07-09 at 15:34 +0000, d.e.warnick@comcast.net wrote:
> Night and day. Beyond the color of the front panel, check out these 2 url's
> http://tentecwiki.org/doku.php?id=560
> http://tentecwiki.org/doku.php?id=561
> Dave
Actually I didn't see much difference in substance on these pages.
Corsair had 4 pole first filter, easily updated with the 8 pole model
220 filter. Corsair II had 5 dB more dynamic range probably because of
the better rejection of the 8 pole filter.

My Corsair II manual says narrow offset tuning is 1.5 KHz, these wiki
say 0.5 KHz. My Corsair II moves much more, as much as 15 KHz with the
wide offset tuning.

Differences I didn't see noted on these wiki that I'm aware of include a
bandswitch output from the Corsair, not on the II, for automatically
switching a PA. The Corsair II has a narrow audio CW filter.

There are grumbles about the sawtooth side tone. It has some advantages,
its simple to make, and it starts and stops as fast as the RF output
without thumps. Its really hard to get a clean sinewave oscillator to
start and stop cleanly at high CW speeds. Its almost necessary to run a
sinewave oscillator continuously and key its output. But then there can
be a click or thump at start and stop unless those switch times are
adjusted to be near zero crossings. One solution would be to run that
oscillator and keying circuit to be an RF oscillator heterodyne to audio
after switching. E.g. a monitor receiver. Long ago using a unijunction
oscillator for AFSK RTTY I found that I could add resistance to the
discharge circuit to make the waveform triangular instead of sawtooth
and that reduced (in theory) the harmonic distortion to 8% total which
is not quite so harsh as that from the sawtooth oscillator. Since of my
first code practice oscillators was a buzzer, the sidetone of the
Corsair doesn't sound all that bad and it truthfully follows the RF

73, Jerry, K0CQ

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