Check out the Telepost Inc. LP-100A digital Wattmeter.
It has user settable SWR alarm points that will open a PTT line to the
amplifier.
I think the Array Solutions version does this also, not sure.
I ordered a LP-100A this week.
I saw this feature as an added bonus to having a fancy wattmeter.
John
wa5zup
> Date: Wed, 21 May 2008 11:16:24 -0400> From: K8RI-on-TowerTalk@tm.net> To:
> aa6eg@hotmail.com> CC: towertalk@contesting.com> Subject: Re: [TowerTalk]
> Castastrophic Consequences of Connector Failure?> > Pat Barthelow wrote:> >
> Folks,> >> > When deciding on the reliability factor in your antenna
> construction, especially when running high power, or with modern solid state
> finals, I wonder what the probability of expensive damage is if an antenna
> connector, or adapter has a "hard" failure, i.e. an open or short
> circuit/flashover, etc. > This should be a concern even when using the best
> of connectors. Sooner > or later something in the feed line or antenna *will*
> fail. In Over the > last 10 years I've had a number of such failures. One, N
> type connector > shorted in the feed line to a center fed half wave sloper.
> The wire > between one side of a balun and another sloper broke at the balun
> > connector. There's no way to gracefully remove the old connector and >
> replace it. Don't k
now why it broke as there as a loop to take out > tension. These were hooked
to a tuner and the output of the Alpha 76 > and 756 Pro. I had water get into a
coax due to an abrasion in the > jacket. It was hanging in open space so I
don't know what caused the > abrasion. That one was between a 40 meter, half
wave, center fed sloper > and the Tokyo Hy-Power HL-1.5Kfx. SWR looked ok, but
it'd give an > immediate shutdown due to SWR when much over 500 watts. I had
the bees > get into the AV640 matching network, which caused high SWR shutdowns
of > the HL-1.5Kfx and ruined about 6 or 8 feet of coax. And finally (as far >
as I can remember "at the moment") the Hygain HDR-300 went past the > stops,
tearing up the rotator loops to the tri-bander and the 7L 6-meter > Yagi.> > I
have experienced few TX failures through the years, due to SWR faults caused by
various antenna system faults. With a high power tube amp, I have heard of
fatal damage inflicted to tubes, or to bandswitches, o
r output network components. On the other hand, I guess we can be lucky, and
sometimes survive an antenna fault without damage to QRO active or passive
path. > I don't know how many times I've heard an arc in either the tuner or >
Alpha. Never any damage though.> > If the probability is high of expensive
damage caused by antenna faults, perhaps it is worthwhile to achieve higher
reliability by using higher quality and care with connector components.> > >
That should be a given, but even with the best it's still going to > happen far
more often than expected.> > Also, I often wondered that it might be a good
widget to have a "trip relay" in an inline > In the old days it was not
uncommon to see a "crowbar" using either an > SCR or relay to short the PS. The
though of those shorting the PS always > bothered me, but they worked fine.> >
meter accessory to quickly, but not instantaneously remove TX power under fault
SWR occurances. I know Bird, has such in the commercial market.
Is damage inflicted to the TX RF chain components by an antenna fault,
usually quicker than a relay could remove/reduce RF power?> > > Many newer
amps, both SS and tube, have protection circuitry built in. > To home brew it's
time consuming and adds noticeably to the expense of > commercial amps, but is
well worth it.> > 73> > Roger (K8RI)>
_______________________________________________> > > >
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