Date: Wed, 07 Jun 2000 09:05:33 -0700
From: Bob Chesley <rchesley@soca.com>
Subject: Terra Radios
To: Lancair List Address <lancair.list@olsusa.com>
Reply-to: rchesley@soca.com
Message-id: <393E72CD.E5F27E3B@soca.com>
Mime-Version: 1.0

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Earl,
    My Terra COM unit was sensitive to lower voltages (when the alternator
wasn't running), still well above the cited figures.  Also, it worked much
better without all the Aux inputs.  Eventually, I removed the four wires
going to the external volume and squelch for the internal intercom, as well
as the Aux inputs for the VOR, MB and handheld audio.  I will be installing
a separate intercom.  Meanwhile it's "ok" with the preset volume and
squelch.  My analysis is that all the wires to the back of the COM were
bringing in RF and saturating the front end of the receiver, causing a
"blanking" of the receiver audio for about 20 seconds after a transmission.
I've seen a similar effect in ham radio receivers.  I can still duplicate
the effect if I inadvertently transmit on the handheld on the frequency the
COM is tuned to (separate antennas but no audio panel for isolation).  It is
as if an r-c circuit was loaded up and finally drains down to release the
squelch, or whatever.
    I made an audio bus that connects the several audio outputs directly to
the headphones.  A degree of isolation was introduced with 500 ohm resistors
in series with the VOR, COM and handheld audio outputs.  Anyway, it works
pretty well now.

Bob Chesley
LNC2 - N4YH (also my ham radio call)

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