On Wed, 11 Jan 2006 18:44:00 -0800, Roy Lewallen
wrote:


I'd venture to guess that the average output power of a 100 watt PEP
sideband rig is no more than about 10 watts unless heavy compression is
being used. And I think you'll find that a 10 watt resistor inside a

Roy, I did some experiments a few years back when the FCC OET formed a
view that the average power of an SSB voice signal was something like
40% of PEP. My experiment was to modulate a TS440 normally with ALC,
with and without compression, and to analyse the audio captured from a
comms monitor. The ratios averaged over 30s that I obtained were -13dB
and -11dB. Those numbers are consistent with the practice in carrier
telephone systems in estimating the power of a n channel multiplex.

Later, I have made the same measurements off-air with FSM which
reports measurements with an average responding detector, RMS
detector, quasi peak detector and peak detector. The results averaged
over seconds were -10 to -15dB. I have no idea where OET got -4dB
(averaged over 6 minutes).

I don't doubt that it is possible to get several dB loss in an ATU,
but it says more about the understanding of the person using it in
that way than the basis for a law for tuner loss.

A chap was telling me on air a few weeks back how good his MFJ tuner
was, it could tune anything. He got 1:1 and discovered he didn't even
have the aerial connected, how good is that! I suggested he take the
covers off and see if the coil support strips had softened / deformed
/ charred. How could I tell him to stop viewing the world through an
SWR meter?

Owen
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