The same rules hold true for Pegasus transistors as with any solid state
component. Spikes, surges, transient voltages gradually eat away at the
device until your Pegasus gradually looses it's wings, power, audio and
finally it's dot turns black.
From: "WA3FIY" <firstname.lastname@example.org>
To: <email@example.com>, firstname.lastname@example.org
Date: Tue, 5 Feb 2002 10:39:35 -0500
Subject: Re: [TenTec] Using Manual Ant Tuner With Pegasus
> On 5 Feb 2002, at 7:36, email@example.com wrote:
> > There isn't any "safe way". Some ways are less dangerous than others.
> > Use something else to tune the antenna then change over to the
> > Pegasus. Palomar had a switchable noise bridge for this purpose.
> I must respectfully disagree that it is dangerous to tune-up a Pegasus
> or any other popular 100 watt transceiver. All major manufactures
> provide warranties on their radios and they would have to have rocks
> in their heads to produce a unit so frail that it would not withstand
> the wide range of abuse the ham radio community will dream up to
> see just how good their engineering departments really are! :-)
> Seriously, it is not uncommon to find intermittent open or shorted
> connections in our feedlines or to inadvertently transmit into the
> wrong antenna and so on. These conditions hardly ever cause
> failure of the PA.
> The PA stage in the Pegasus is robust and well protected against
> catastrophic failure modes, so don't worry about doing damage to
> the finals. Someone in an earlier post said that the only protection
> on a Pegasus is the fuse. Not so! Beginning with the Paragon I
> believe, all TT 100 watt radios have included a current limit sensor
> to fold back drive when the PA current reaches design max levels.
> In my opinion this is a much better design than SWR fold-back
> because it is current, not SWR that damages transistors. As I recall,
> the Motorola MRF 45X series transistors were able to operate into
> infinite SWR. All transistors have finite voltage and current limits
> however. I know TT is now using a different transistor part number
> in the PA and I don't know it's SWR rating but I'll bet it is about the
> same as the Motorolas.
> That said, I'm not suggesting we deliberately abuse our radios and I
> agree that it is good practice to reduce power during tune, not so
> much to protect the radio as to comply with FCC rule 97.313(a) and to
> be considerate of others using the band.
> Just follow the instructions for your tuner, use minimum power
> needed and fear not! Your Pegasus will live a long and healthy life
> and your stress level will be much lower. Hey..........this ham radio
> stuff is supposed to be fun!!!! :-)
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