In article , Patrick Turner
wrote:

The "poor" AC/DC" load ratio does not matter if the output audio voltage asked
from the circuit is
low.

But the "audio voltage asked from the circuit" is not low when the
negative modulation percentage is high, it is actually quite high
relatively speaking. I think you have to do some more thinking about how
diode envelope detectors actually work.

In a triode gain stage, if the DC carrying RL is large, and the cap coupled
load is small,
a similar effect occurs, and positive voltage swing is limited to a lot less
than the B+.
But the first few volts are still quite linear, and simply what one expects
when load liane analysis is used.

A triode gain stage is not a good analogy, as the signal level can be
independently adjusted for a reasonable amount of distortion. In a
detector it is the transmitter that controls the modulation, and there is
not a lot you can do about it short of somehow adding in more carrier, or
filtering out some of the sidebands.

My own radio uses a good enough AC/DC load ratio to take the cut off effect
fully into account.

That may well be, but it certainly wasn't the case with the AM tuner
schematic that you posted.


Regards,

John Byrns


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

John Byrns wrote:

In article , Patrick Turner
wrote:

The "poor" AC/DC" load ratio does not matter if the output audio voltage asked
from the circuit is
low.

But the "audio voltage asked from the circuit" is not low when the
negative modulation percentage is high, it is actually quite high
relatively speaking. I think you have to do some more thinking about how
diode envelope detectors actually work.

I suggest you try my circuit, before you say I dunno how enevlope detectors work.



In a triode gain stage, if the DC carrying RL is large, and the cap coupled
load is small,
a similar effect occurs, and positive voltage swing is limited to a lot less
than the B+.
But the first few volts are still quite linear, and simply what one expects
when load liane analysis is used.

A triode gain stage is not a good analogy, as the signal level can be
independently adjusted for a reasonable amount of distortion. In a
detector it is the transmitter that controls the modulation, and there is
not a lot you can do about it short of somehow adding in more carrier, or
filtering out some of the sidebands.

Build a better detector, for a start.



My own radio uses a good enough AC/DC load ratio to take the cut off effect
fully into account.

That may well be, but it certainly wasn't the case with the AM tuner
schematic that you posted.

All the circuits I have posted work fine.
Better than most commercial bean counter driven designs.

If you don't try my circuits, maybe you'll never know how good they are.

Make the measurement comparisons between what I have posted,
and what exists in a typical junky radio laying around.

I am not afraid of your test results.

Patrick Turner.



Regards,

John Byrns

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