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[TenTec] Ten-Tec PA design

To: tentec@contesting.com
Subject: [TenTec] Ten-Tec PA design
From: Bill Tippett <btippett@alum.mit.edu>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Fri, 14 Jul 2006 12:42:27 -0400
List-post: <mailto:tentec@contesting.com>
K4KGY wrote:

 >The question of why TT didn't included a breaker instead
of a fuse--well in a way they did--it's in their matching power
supply. This is an electronic breaker not a magnetic and it works
as good if not better than the magnetic. The fuse in the rig is
then just a backup to protect the wiring system in case the
breaker should fail and to protect same if someone uses other
than a TT power supply. TT has always recommended to use an
Air-Pax breaker if their power supply was not used and if sized
correctly it works fine.

         Thanks Jim!  Someone else responded privately that
Orion internally has a current limiting circuit (see below):
The Orion I has a "current limit" circuit in it that limits the PA supply
current by reducing RF drive to the PA when current exceeds a set level.
Reference A5 ALC Circuitry  R19  and A0 Input/Output R63 sense resistor.
The SWR forward and reflected signals only drive the display to tell you
that you have a bad swr. (This surprised me a bit I thought they would be
using that also in addition  - but the current limit by drive reduction is a
semiconductor manufacturers dream! ) I can't remember exactly what TT told
me to set current limit at - but it was something like 20 amps (which pretty
well fits the max current spec of 23 amps for the radio).My senior moment
says 21.8 amps but don't believe that without talking to TT.

         I also checked the most recent versions of both the
Orion and Orion II manuals under "Power Supply" and there
is *no* mention of any external circuit breaker.  Maybe
the circuit above precludes the need for one.

         Being a paranoid type, I think I'll install
one just to be safe.  Does anyone know the correct
Air-Pax model to use with Orion?

                                         73,  Bill  W4ZV

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