I have managed to melt solder etc in maladjusted ATUs with 100W power
levels.The advice about lamp or thermocouple meters in the feedline is good,
only needs to be used when setting up. Once characteristics of the system
are known one can use the input bridge readings.
73
end
Barry Kirkwood PhD ZL1DD
Signal Hill Homestay
66 Cory Road
Palm Beach
Waiheke Island 1240
NEW ZEALAND
www.waiheke.co.nz/signal.htm
----- Original Message -----
From: Tom Rauch <w8ji@akorn.net>
To: AMPS <amps@contesting.com>; Peter Chadwick <Peter.Chadwick@zarlink.com>
Sent: Monday, February 18, 2002 11:35 AM
Subject: RE: [AMPS] Power out indicator
>
> > >Tuners need only a reflectometer to indicate when zero reflected
> > >power is obtained during adjustment.
> >
> > Generally speaking, I agree with Rich. However, some tuner circuits
> > can be tuned up to have a very low input SWR and no output, with the
> > tuner losses being transformed up to 50 ohms. The result is that the
> > smoke gets let out of the tuner parts - or the solder out out of the
> > joints! Of course, these tuners can also be tuned to have a very low
> > input SWR because they're doing the job correctly.
>
>
> I hear that rumor repeated, but I've never been able to find that in
> any tuner I have ever seen.
>
> What does happen is there is a smooth and gradual reduction in
> efficiency as the Q is made higher, but that reduction is so slight
> no one would notice the loss in power transfer. Even the smallest
> amount of loss will destroy a tuner if power is high, since the loss
> is generally confined to one small area of the inductor. Typically as
> little as 50 watts of power loss will can ruin an inductor on
> sustained CW or RTTY operation.
>
> It also would be impractical to measure power in the varying load
> part of the system, and most people find the power meter
> convenient. I use ATR30's here all the time, mostly because it has
> a good peak reading meter and antenna switch inside. When I
> need to, I can "touch up" a high SWR to work a WARC band or a
> frequency out of range of one of my narrow antennas. It is a multi-
> function advantage to have a good directional coupler.
>
>
> 73, Tom W8JI
> W8JI@contesting.com
>
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>
>
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