In article ,
Patrick Turner wrote:
On Jul 10, 3:48*am, John Byrns wrote:
In article
,
*Patrick Turner wrote:
On Jul 9, 9:19*am, John Byrns wrote:
[Much off topic drivel snipped]
You may well delete "drivel" like so many others here who have awful
personalities who cannot cope with being human or nice in any way. Ah
you going senile? Just can't cope with well rounded discussions? Its
OK, you don't have to hide such characteristics.
Your drivel is a fine topic for discussion, the problem is that it is off
topic
in this group and you should take it elsewhere.
I see no reason not to include some background information which
indirectly relates to the subject.
I don't see how your so called "background" information relates even
"indirectly" to the subject, it just plain doesn't belong in this group.
I've read the tonnesoftware.com site before and there's nothing there
that works better than my circuits using tubes, and I got less wave
form distortion that they show on their oscillograms.
The detectors used in the modulation monitors, the General Radio 1931,
Gates
M5693, and Belar AMM-2/3 don't appear to have any visible waveform
distortion,
although your eye is probably more sensitive to this type of aberration
than
mine. *In my defense, back in the days before I became senile, when I
worked in
the radio design factory, where we were designing "white goods" radios and
measuring power output at the 5% distortion level, I was consistently able
to
set the signal level where 5% distortion occurred without reading the meter
on
the distortion analyzer, looking only at the waveform displayed on the CRO.
Don't worry, when, or if I become senile, i'll not recognise 5% ona
CRO when its there. But most waves at that site showed slew
distortions and cut off distortions and so forth, all of which can
easily be avoided or minimised to be below 1% with my circuit over a
wide AF range and if the output voltage 1 Vrms.
Yes, there are plenty of distortions shown to illustrate the various problems
that can occur in a poorly designed detector, and what causes the distortions.
There are also plenty of undistorted waves shown at that site, with distortions
of less than 1%, to illustrate the good results that can be achieved with
careful design.
But even where one
listens to short wave where AF detector output 0.1Vrms, the sound is
good, although rather mauled by having travelled so far and being so
riddles with noise and fading up and down. I have never ever seen any
old radio or any old schematic of what was used for detecting AF for
use in re-broadcasting.
I found a schematic for an old Telefunken AM rebroadcast receiver, a.k.a.
"Ballempfänger", on the web. It was a rather complex radio although IIRC it
used a straightforward vacuum diode detector.
AFAIK, not one single commercial example
exists of a radio with "infinite impedance detector" even though the
Selsted & Smith example is given in RDH4, page 1,495, Figs 27.56,
27.57
RDH4 does not have anything that works as well as what I invented for
myself 14 years ago.
In the US J.W. Miller offered both commercial AM tuners and Radios using the
infinite impedance detector, I have one of their AM Tuners. Altec Lansing also
offered an AM-FM tuner that used the infinite impedance detector in the AM
section. Sargent Rayment also offered a line of tuners and receivers that used
the Selsted & Smith detector in the AM sections. Ampex also built an AM-FM
tuner that used a perverted variant of the Selsted & Smith detector, I also have
one of these.
It's hard to beat a carefully designed diode detector though.
Most bean counters justify their employment by being able to reduce
the parts and labour needed to make something, and therefore
increasing shareholder profits and most often reducing the sound
quality and reliability in electronics produced by the company.
The opposite approach, of adding components that serve no useful function is
just as bad, actually worse.
--
Regards,
John Byrns
Surf my web pages at,
http://fmamradios.com/