My Manual for the TT 961 Power Supply states that the Current Limiting is
factory set at 22 Amps.
The Output Voltage is set at 13.8 (adjustable from 11.5 to 15.0 volts)
----- Original Message -----
From: "Bill Tippett" <firstname.lastname@example.org>
Sent: Friday, July 14, 2006 12:42 PM
Subject: [TenTec] Ten-Tec PA design
> 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
> 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
> 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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