> That's what I was able to see, Tom. The IM products were
> much stronger with white noise & max ALC than with speech
> & no ALC or even speech with ALC. I did *NOT* do very
> comprehensive testing, in the lab, so I'm borrowing an HP
> spec any tomorrow to do some more detailed testing. What
> tones should I use? I read the section on your site about
> injecting a "warbling" tone a while back -- I believe that
> was at 100 Hz (??). Given my audio bandpass is roughly
> 20Hz to 4kHz @ -6dB, I can do some pretty interesting
> testing.
Joe,
In order for ALC problems to be measured, you have to let
the ALC actually do something meaningful. Any test that
holds the ALC steady, such as a white noise or two-tone
test, will not test ALC dynamics at all. The fact you
overdrove the ALC simply means you saturated the ALC control
system and effectively disabled it. It is no surprise a
saturated radio gets wide.
The same is true for anyone testing a linear amplifier. A
linear amplifier that is terrible for dynamic regulation of
power supplies, be they bias, HV, or screen, will almost
always look significantly better when tested with a steady
average power source like a noise test or a two-tone test.
To actually test something that amplifies speech, the test
must have the characteristics of speech. That includes the
off and on characteristics like spaces between words and
syllabic rate changes, as well as the tones.
The problem with wide-fi is best left for other forums, but
anyone who understands IM products, receivers, and
transmitters also knows the bass hurts BW as much as the
extra highs. I, like many others, don't have a problem in
the world with wide-fi on empty bands. Hogging up extra room
on a crowded band is selfish. It would also be nice if the
cutting edge technical information sites for ESSB actually
knew how RF systems and measurements worked. It doesn't
reflect well on a group that often claims to be cutting edge
technically when people see single tone or non-dynamic tests
to measure bandwidth.
73 Tom
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