-----Original Message-----
From: davisr [wd8jja@arrl.net] <WD8JJA@arrl.net>
To: amps@contesting.com <amps@contesting.com>
To: <amps@contesting.com>
Date: 15 October 2001 02:27
Subject: [AMPS] FL-2100B SWR Metering
>Hi, I am a new subscriber to the list, but here goes.
>Does anyone have any experience with calibrating the SWR meter in the
>FL-2100B??
>Mine appears to work okay otherwise, but the SWR reading differs from two
>other meters in series with it.
>There is not much difference when looking into a 50 ohm load. But into a
>trap-vertical, or my tuner,
>the readings are around 2.0 to 2.5:1 when the other meter(s) read < 1.5:1.
>If I adjust the tuner so that the FL-2100B shows 1.1 to 1.5, the other
>meters go up to about 2.5 and the power
>output drops from about 700 - 800 watts down to around 400 or so.
>Any help would be appreciated.
The problem arises when a meter doesn't have enough directivity - in other
words, some of the forward power leaks into the reverse power detector.
Depending on the phase, this adds to or subtracts from the real reverse
power, giving a false reading that is higher or lower than real. From what
you describe, the FL2100 appears to be wrong. To correct it, you need a load
that is known to be a good acurate 50 ohms. Run the amp into it, and adjust
the coupler (assuming there are adjustments available) to null the reverse
power reading. Worth checking for duff joints and burnt out components
first.
73, Steve
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