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Telamon · July 30th 06, 11:05 PM posted to rec.radio.shortwave

In article .com,
wrote:

wrote: snip
Except we are not talking about IF filters .The "fading" filter is
at the end of the chain, i.e. past the demod.

snip

Except this is at audio frequencies, where the component sizes are
much larger. Again, this is not at IF frequencies.

Mr. Lankford's main concept is that by using a narrow enough IF
filter, a narrow filter with with a step attenuation skirt, and by
offset tunning to only get the carrier and the desired sideband, and
with a following suitable AF LP fitler can do wonders. It is not
magic, and doesn't work with every receiver and under every
condition. In the ret of this, and all future posts, I will simply
call it "ELPAF".

I can say is that it is a usefull technique, and will even help when
used premium receiver like an AOR7030 or R390, the filter can really
reduce the effects of "fading". With a modest receiver like the R2000
that has

been upgraded with a suitablely narrow IF filter, the results are
impressive. With a "marginal" receiver like the ATS909/DX398 the
results are nothing short of amazing.

Any time you narrow the frequency range with a filter you lower the
noise floor possibly making the faded carrier large enough so the
detector does not greatly distort the audio.

--
Telamon
Ventura, California