Limiting PA current limits PA input power. But output power can vary with
the load impedance. Since the dissipation is the PA difference between
these, it would seem that limiting the current would not be sufficient
protection except short-term. Where is my thinking going wrong?
73, Mike N4NT
----- Original Message -----
From: "Carl Moreschi" <n4py@earthlink.net>
To: <tentec@contesting.com>
Sent: Friday, May 09, 2003 10:09 AM
Subject: Re: [TenTec] Orion SWR protection
> The Orion has protective circuitry to limit the current in the finals to a
> safe value. There is no point where SWR "fold back" occurs. It just won't
> let the current in the finals get too high. This is an excellent
protection
> method.
>
> Carl Moreschi N4PY
> Franklinton, NC
> ----- Original Message -----
> From: "Pete Smith" <n4zr@contesting.com>
> To: <tentec@contesting.com>
> Sent: Friday, May 09, 2003 12:35 PM
> Subject: Re: [TenTec] Orion SWR protection
>
>
> > At 05:33 AM 5/9/03 -0400, you wrote:
> > >The specification of "25 amperes" covers ORION's performance under all
> > >specified
> > >conditions, but if your antenna impedance is between 50 and 100 ohms,
> > >including
> > >moderate reactance, a 22-ampere power supply will run ORION at close to
> > >full power. If
> > >you must have full power under all specified conditions, ORION needs 25
> > >amperes.
> > >
> > > Simple answer is, full rated power at SWR 2.0:1 and below.
> >
> > This looks suspiciously like a similar statement in my Mark 5 manual,
but
> > the Mark 5's protection kicks in rapidly and rather below 2:1 indicated,
> > while that in the TS-930 comes into play more gradually. I guess I
could
> > have asked the question better -- how aggressively does the Orion
ACTUALLY
> > reduce the output power as the SWR approaches 2:1, and what part does
> > reactance play in that? Presumably, it isn't just a question of 25-100
> > ohms resistive... what is "moderate reactance," to borrow the term used
in
> > the manual?
> >
> > 73, Pete N4ZR
> > The World HF Contest Station Database was updated 11 April 03.
> > Are you current? www.pvrc.org/wcsd/wcsdsearch.htm
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