Well Dan it looks like you have definitely found the birdies. I tried to
reduce some of them but didn't have too much luck. In a 1997(?) "Omni V,
562 Supplementary Data" sheet from the factory they said the following about
the issue:
"BIRDIES. There are many weak birdies that can be heard without an antenna
connected. By actual count, there are 56 than (sic) can be heard in the
allocated ham bands, without an antenna. All but 13 of these birdies are
S-1 or less and disappear when an antenna is connected and there is signal
propagation. Nine of these, that can be heard are at S-3 or so, are spread
throughout the ten meter band. The other 4 are at 3.6, 3.999, 21.332 and
21.363 MHz. Most of them are biproducts of the mixing scheme used and all
cost effective methods to eliminate them, or reduce their amplitude, have
been applied. The notch filter will get them out of the way, if needed.
Our evaluation of competitive equipment supports the conclusion that any
receiver without spurious signals is either very expensive
(commercial/Military variety) or the sensitivity has been compromised, or
both. Other techniques that we have observed for controlling spurs, burbles
and pops include the use of a full time noise blanker and/or simply
eliminate the frequency from the tuning range of the receiver, with
software. Our philosophy is to optimize performance, minimize the spurious
emissions where practical, and be honest with you."
I have worked on my own Omni V to try and reduce the birdies and if you're
interested my report is published on my website.
I hope this helps!
73,
Rick
VE7TK
Website: http://www3.telus.net/ve7tk
-----------------------------------------------------Date: Thu, 2 Sep 2004
13:57:36 EDT
From: OTAKEBI@aol.com
Subject: [TenTec] Birdies on Omni V Question?
To: tentec@contesting.com
Message-ID: <df.16f7c2.2e68b910@aol.com>
Content-Type: text/plain; charset="US-ASCII"
I just noticed after a year of having an Omni V that I get tones on
28.448.58
through 28.448.65.
The lowest tone starts at 28.448.58 USB and the tone goes up in steps to the
highest at 28.448.58.
These tones are being generated in the radio because I can hear them with
the
antennae off.
I tuned my Corsair II to the same freq. and no tones.
I can also hear the tones on CW at 28.451.05 through 28.448.65.
Are these the infamous birdies I have heard about?
Dan/N4VET
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