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Realistic Pro- 34 Mods
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PRO34.1
From: [email protected] (Bob Parnass, AJ9S)
Subject: Eliminating a birdie in the PRO-34 portable scanner
Organization: AT&T Bell Laboratories - Naperville, Illinois
PRO-34 BIRDIE ELIMINATED
by Bob Parnass, AJ9S
Birdies are unwanted signals generated within a receiver,
which cause the receiver to "hear itself." Some birdies
are caused by the unwanted product of the local oscilla-
tor. Another cause is a stage, which oscillates but
isn't meant to oscillate, such as a high gain intermedi-
ate frequency (IF) amplifier.
Most birdies, especially those generated by a local
oscillator, are frequency stable. It's difficult to rid
a radio of these birdies, and solutions usually involve
better internal shielding and isolation among the stages.
A "wandering birdie" is one which changes frequency.
Wandering birdies, and birdies which appear and disappear
suddenly, may be caused by intermittent ground connec-
tions within the radio, or defective bypass capacitors.
CONTINUED IN FILE PRO34.8
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