In article , Patrick Turner
wrote:

John Byrns wrote:

You have still haven't enlightened us with some concrete information about
how much, if at all, your biased diode detector really helps reduce the
distortion of the diode peak envelope detector.

It should be *obvious* from the circuit!

It's not, at least not to those among us, such as myself, who are not so clever.

My circuit is as simple as it gets.
Hve the cathode of the CF at +50v, and have a 1M R to drain 0.05mA
through the diode. Much more current could be used.

This method means that detection of weak signal lower than the forward voltage
of the Ge diode of 0.27v peak approx are not subject to the non linear turn on
of the diode, ie, there is no clipping by the diode.

Is what you are saying is that the diode in your circuit is always "turned on"?

Quantity not quality was what dominated radios in old days.

If you wanted better sound, you bought a Quad AM tuner, which only
rich folks could afford.

I have one of those "rich folks" Quads right here next to my computer, and
I guess those "rich folks" got taken as the Quad uses a common vacuum
diode detector, like a common kitchen radio, nothing special, the only
special care taken in the detector design seems to be that the audio
output is tapped way down on the diode load resistor to minimize negative
peak clipping.

You could better make your point if you posted a couple of graphs for
distortion vs. signal level for a diode detector, with and without bias,
and for several modulation levels, maybe 80% and 100%.

My biased SS diode has lowest thd at high levels of signal.

One would expect you to be an advocate of your on circuit, but how low is
the thd at high modulation levels?

But if you have a normally gronded last IF coil feeding a diode to 100pF
with a typical 1M discharge R to ground, then with low signals on weak
stations,
the thd is appalling, and I thought such issues would be obvious to anyone
familiar with diode operation. No need for me to copy out
the wave form analysis I did, build a detector like I have and you won't be
dissapointed!

Actually your wave form analysis would be very interesting to see indeed.
The impedance of the IFT is quite low at the harmonic frequencies in the
diode current wave form so the diode sees a low impedance drive at those
frequencies even without a cathode follower, and the filtering effect of
the IFT prevents the harmonics in the current pulses from reaching the
plate of the IF amplifier. See the discussion on page 1077 of the RDH4
relative to loading of the IFT secondary by the diode,although much more
comprehensive discussions can be found elsewhere.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/

In article ,
(John Byrns) wrote:

In article , Patrick Turner
wrote:

John Byrns wrote:

You have still haven't enlightened us with some concrete
information about how much, if at all, your biased diode detector
really helps reduce the distortion of the diode peak envelope
detector.

It should be *obvious* from the circuit!

It's not, at least not to those among us, such as myself, who are not
so clever.

My circuit is as simple as it gets. Hve the cathode of the CF at
+50v, and have a 1M R to drain 0.05mA through the diode. Much more
current could be used.

This method means that detection of weak signal lower than the
forward voltage of the Ge diode of 0.27v peak approx are not
subject to the non linear turn on of the diode, ie, there is no
clipping by the diode.

Is what you are saying is that the diode in your circuit is always
"turned on"?

Snip

Congratulations for the continuation of one of the most retarded
threads I've yet read. Never heard of biasing a diode or being unable
to understand doing so is pretty pathetic. Electronics does not get any
simpler than this.

Why don't you cross post this to more news groups so more people can
have a laugh.

--
Telamon
Ventura, California

Telamon wrote:

In article ,
(John Byrns) wrote:

In article , Patrick Turner
wrote:

John Byrns wrote:

You have still haven't enlightened us with some concrete
information about how much, if at all, your biased diode detector
really helps reduce the distortion of the diode peak envelope
detector.

It should be *obvious* from the circuit!

It's not, at least not to those among us, such as myself, who are not
so clever.

My circuit is as simple as it gets. Hve the cathode of the CF at
+50v, and have a 1M R to drain 0.05mA through the diode. Much more
current could be used.

This method means that detection of weak signal lower than the
forward voltage of the Ge diode of 0.27v peak approx are not
subject to the non linear turn on of the diode, ie, there is no
clipping by the diode.

Is what you are saying is that the diode in your circuit is always
"turned on"?

Snip

Congratulations for the continuation of one of the most retarded
threads I've yet read. Never heard of biasing a diode or being unable
to understand doing so is pretty pathetic. Electronics does not get any
simpler than this.

Why don't you cross post this to more news groups so more people can
have a laugh.

Are you implying that those involved in this thread are retarded?
or mentally deficient?

I don't care that you have a good laugh.

I know that many ppl in the groups to whom this thread is being posted
don't have much of a clue about how AM radios work, let alone an FM set,
or its MPX stereo decoder, or let alone a TV set, or VCR, or CD player.

Hell, I damn well can't understand the schematic for the Space Shuttle,
and I knows the laughter over this must be deafening, but heck, I don't
care.

To many folks the simplest of concepts are difficult to understand,
and they restore their radios and amps using age old circuits
which perform woefully most of the time.
I am happy if I bring some simple alternative techniques for them to apply
if they want, but most won't, because the idea of drilling more tube socket

holes in an existing set is butchery.
I care for more fidelity, and to get it, serious butchery is required,
sometimes totally banishing the original old fashioned ideas altogether,
removing all vestige of the old maker's design, and placing my own label on
the chassis.

The old maker may have been delighted that he got the thd down to 5%, audio
bandwidth
from 150 Hz to 2 kHz, with some hum, but I wasn't.

Patrick Turner.




--
Telamon
Ventura, California

In article ,
Patrick Turner wrote:

Telamon wrote:

In article ,
(John Byrns) wrote:

In article , Patrick Turner
wrote:

John Byrns wrote:

You have still haven't enlightened us with some concrete
information about how much, if at all, your biased diode detector
really helps reduce the distortion of the diode peak envelope
detector.

It should be *obvious* from the circuit!

It's not, at least not to those among us, such as myself, who are not
so clever.

My circuit is as simple as it gets. Hve the cathode of the CF at
+50v, and have a 1M R to drain 0.05mA through the diode. Much more
current could be used.

This method means that detection of weak signal lower than the
forward voltage of the Ge diode of 0.27v peak approx are not
subject to the non linear turn on of the diode, ie, there is no
clipping by the diode.

Is what you are saying is that the diode in your circuit is always
"turned on"?

Snip

Congratulations for the continuation of one of the most retarded
threads I've yet read. Never heard of biasing a diode or being unable
to understand doing so is pretty pathetic. Electronics does not get any
simpler than this.

Why don't you cross post this to more news groups so more people can
have a laugh.

Are you implying that those involved in this thread are retarded?
or mentally deficient?

Yes, are you having trouble comprehending that?

--
Telamon
Ventura, California

Are you implying that those involved in this thread are retarded?
or mentally deficient?

Yes, are you having trouble comprehending that?

I think you have a problem with basic human communication skills,
and the ability to define personal attributes in an appropriate manner.
I suspect nearly everyone here would agree.

It does not worry me in the least about whatever conclusions you have come to
over the issues I have just raised, or how you propose to remedy your
shortcomings.

But one thing seems certain, and its that you have not contributed much of
worth
which is relevant, helpful, interesting, informative or cheerful in the recent
discussions in this thread.

Patrick Turner.

Telamon wrote:
In article ,
Patrick Turner wrote:


Telamon wrote:



Are you implying that those involved in this thread are retarded?
or mentally deficient?


Yes, are you having trouble comprehending that?


Well yeah. Some ideas simply don't float well in the face of r.r.s

In article ,
Patrick Turner wrote:

Telamon wrote:

In article ,
(John Byrns) wrote:

In article , Patrick Turner
wrote:

John Byrns wrote:

You have still haven't enlightened us with some concrete
information about how much, if at all, your biased diode detector
really helps reduce the distortion of the diode peak envelope
detector.

It should be *obvious* from the circuit!

It's not, at least not to those among us, such as myself, who are not
so clever.

My circuit is as simple as it gets. Hve the cathode of the CF at
+50v, and have a 1M R to drain 0.05mA through the diode. Much more
current could be used.

This method means that detection of weak signal lower than the
forward voltage of the Ge diode of 0.27v peak approx are not
subject to the non linear turn on of the diode, ie, there is no
clipping by the diode.

Is what you are saying is that the diode in your circuit is always
"turned on"?

Snip

Congratulations for the continuation of one of the most retarded
threads I've yet read. Never heard of biasing a diode or being unable
to understand doing so is pretty pathetic. Electronics does not get any
simpler than this.

Why don't you cross post this to more news groups so more people can
have a laugh.

Are you implying that those involved in this thread are retarded?
or mentally deficient?

I don't care that you have a good laugh.

.... and I don't care if you and Byrns look like idiots. The threads at
100 now and I'll check back in when it hits 500.

--
Telamon
Ventura, California

I un-retarded this technical thread as a favor to rrs's Twains of Today, the
Modern Menckens and our Real Time Roykos.

Others are invited to follow along. However, I may miss much of it. To
paraphrase General Stonewall Jackson, I've killfiled 'em. Killfiled 'em
all.

Frank Dresser

"Frank Dresser" wrote in message ...
I un-retarded this technical thread as a favor to rrs's Twains of Today, the
Modern Menckens and our Real Time Roykos.

Others are invited to follow along. However, I may miss much of it. To
paraphrase General Stonewall Jackson, I've killfiled 'em. Killfiled 'em
all.

Frank Dresser

Musta killfiled 'em all. Good work! (I think?)

Telamon wrote:

Congratulations for the continuation of one of the most retarded
threads I've yet read. Never heard of biasing a diode or being unable
to understand doing so is pretty pathetic. Electronics does not get any
simpler than this.

John understands this stuff extremely well: I've argued detector issues
with him on rec.antiques.radio+phono in the past. John obviously doesn't
believe Patrick really understands what he's advocating.

Biased diode envelope detectors are *not* simple: I've used them for
x-ray spectroscopy with scintillation counters, and they are tricky
beasts. A biased diode is far from an ideal switch: its dynamic
resistance varies with instantaneous signal level, making the circuit
bandwidth vary rapidly. The mathematics of this are rather difficult.

I also think an emphasis on detector distortion under idealized test
conditions misses the real issues. The most annoying distortion on AM
signals doesn't come from the detector. Multipath, steep IF skirts, and
AGC all distort the modulation envelope. Perfect reproduction of such
distorted envelopes yields bad sound. I suspect that the great sound of
the old tube diode detectors actually results from their poor
reproduction of these sorts of envelope distortion (but this is a
difficult hypothesis to test).

In any case, my 1934 Stromberg-Carlson 58-T, with its weak AGC, poor
skirt selectivity, and a classic diode detector has the best sound of
any of my AM radios, both to my ears and my wife's. One receiver it
beats is my Drake R-8, which uses a very low distortion (active full
wave rectifier) envelope detector. Of course, the R-8 is a much better
DX machine, but that's a different issue.

-jpd