wrote:
wrote:

As a demod filter? I would image a low order active filter to clean
things up. Remember, this is the audio band, not RF. I've seen some
write ups on 455khz IFs being done with active filters.

Kiwa sells an active filter for 455Khz
http://www.kiwa.com/kiwa455.html

Note the AR7030 has "tone controls", so certainly it has an active
filter past the demod. The problem with building LCR filters in the
audio band is they are bulky, not to mention often inaccurate. With
active filters, you have more flexibility over component values.

Drake uses an LC filter in the IF. They "Get away" with it becuase of
the
lower IF they use. R390s, original not the R390A, and the R392 use
several staged of LC filters and have excellent skirts.

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


The Kiwa filter you refference is not a "active filter", but a ceramic
filter
with amplification. To me active filter means opamp or norton amp
with feedback to control pass/reject charactoristics. The premium Kiwa
unit is nearly as good as a crystal or mechanical filter and MUCH
easier
to connect. I installed one in a friends R2000 and was impressed by
the quality and how well it worked.

A big advantage of passive LC filters is they are much less "fussy"
then active filters. I like not having to mess with power and proper
bypassing.
And if you are willing to wind your own torroids, it is pretty easy to
get the
L very close to what you want. The C can be built with standard value
caps in parallel.

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




The Tone-Tilt filter I used in all 3 of our R2000s is active because it
would be
VERY difficult to use LC filters effectively.

Terry

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.

Terry

On 30 Jul 2006 09:06:34 -0700, 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.

Terry

I used a similar technique with my R-390A. I'd tune one side of the
carrier and use the BFO to provide a local one. You have to back way
off on the RF gain as the 390A BFO is sort of weak.

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.

Almost sounds like the 'syncho-phase' detector on the R7/A. Use of a narrower
filter and tilting the passband control to either USB/LSB.

dxAce
Michigan
USA

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

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".

My point still holds in that nobody serious builds LCR filters for
auido (speaker crossovers exempted). His LCR filter IS in the audio
chain, not the IF.




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.

Terry

wrote:
wrote:
snip

My point still holds in that nobody serious builds LCR filters for
auido (speaker crossovers exempted). His LCR filter IS in the audio
chain, not the IF.


Your comment that "nobody serious" is so off base as to be asiniine.
Dallas Lankford is clearly one of most serious DXers alive today.
Why not take a look at all the technical information at
http://www.kongsfjord.no/dl/dl.htm
before jumping to silly conclussions.

Terry

wrote:
wrote:
wrote:
snip

My point still holds in that nobody serious builds LCR filters for
auido (speaker crossovers exempted). His LCR filter IS in the audio
chain, not the IF.


Your comment that "nobody serious" is so off base as to be asiniine.
Dallas Lankford is clearly one of most serious DXers alive today.
Why not take a look at all the technical information at
http://www.kongsfjord.no/dl/dl.htm
before jumping to silly conclussions.

Terry

I've done (as in been paid for) filter design in telecom/datacom
applications, including elliptic filters, delay equalizers, etc. I know
of what I speak.

There is a leapfrog design on this page if you want to educate
yourself:
http://www.filter-solutions.com/active.html

wrote:


I've done (as in been paid for) filter design in telecom/datacom
applications, including elliptic filters, delay equalizers, etc. I know
of what I speak.

There is a leapfrog design on this page if you want to educate
yourself:
http://www.filter-solutions.com/active.html


I give up, you win.
Only idoits and fools would bother to build any passive
AF fitlers. Please build all the active ELPAF filters your
heart desires. I made the mistake of assuming you where
a serious SWL.

I bet you would find the thought of building a clipper to limit
the AF level to a set of earphones with something as simple
as a couple of parallel 1N4004 diodes and a series resistor
so repulsive as to nearly make yo puke.

I can hear it now, "Oh My God, how simple."

I bet you could whip up a active limiter that would achieve
+/-0.0001dB clipping accuracy.

Too bad you make Cuhulin seem reasonable.

I can't PLONK you with Google beta, but I damn sure will ignore
your posts.

Terry

Hey, is idoit something like an idiot?

Your reaction is bizzare to say the least, but plonk away.

wrote:
wrote:


I've done (as in been paid for) filter design in telecom/datacom
applications, including elliptic filters, delay equalizers, etc. I know
of what I speak.

There is a leapfrog design on this page if you want to educate
yourself:
http://www.filter-solutions.com/active.html


I give up, you win.
Only idoits and fools would bother to build any passive
AF fitlers. Please build all the active ELPAF filters your
heart desires. I made the mistake of assuming you where
a serious SWL.

I bet you would find the thought of building a clipper to limit
the AF level to a set of earphones with something as simple
as a couple of parallel 1N4004 diodes and a series resistor
so repulsive as to nearly make yo puke.

I can hear it now, "Oh My God, how simple."

I bet you could whip up a active limiter that would achieve
+/-0.0001dB clipping accuracy.

Too bad you make Cuhulin seem reasonable.

I can't PLONK you with Google beta, but I damn sure will ignore
your posts.

Terry