In article ,
says...

I remember seeing ads in QST in the 1960's for a device I think was
called "Echoplex." It was supposedly used on commercial and military
voice communications circuits. I never heard one of these in use by a
ham, probably because their cost could buy several Collins S-Line
stations. Doing a Google search brings up lots of echo-effects
processors for guitars and such, but I found nothing for communication
usage. Do any readers here remember the device and its manufacturer
and how it worked?

I have a feeling it's another name for Lincompex, developed by the
British Post Office in 1966. Bell labs in the US apparently then came up
with something very similar - which I seem to remember was named
"Echoplex". Could be wrong - it was all a long time ago.....

Lincompex stands for LINKED COMPRESSOR and EXPANDER. The audio is
heavily compressed, and the pre-compression amplitude variations are
used to frequency modulate a 2900Hz control tone. This is combined with
the compressed audio (300-2700Hz) and fed to the TX. At the other end of
the circuit, the control tone is used by an expander to restore the
original amplitude variations.

Lincompex was used widely on international point to point SSB and ISB
voice circuits - and may still be in use (?)

The equipment was made by Marconi, and possibly ST&C (as was, before
Nortel bought them up).

You are both right.

On a 1966 issue of QST magazine, I found the advertisement of "Echoplex" by Kahn
Research Laboratories. It sold for more than 300$, which was not cheap at those
times.

As to Lincomplex, I remember a friend of mine working for Page Europe who told
me having installed Lincomplex on HF transmitters in Africa.

73

Tony I0JX
Rome Italy

"Antonio Vernucci" wrote in message
...
You are both right.

On a 1966 issue of QST magazine, I found the advertisement of
"Echoplex" by Kahn Research Laboratories. It sold for more than 300$,
which was not cheap at those times.

As to Lincomplex, I remember a friend of mine working for Page Europe
who told me having installed Lincomplex on HF transmitters in Africa.

73

Tony I0JX
Rome Italy

Thank you, Tony.

Somehow, I think you are talking about Leonard R. Kahn of Kahn Research
Laboratories in Freeport, Long Island, NY, and not A. Q. Khan of Khan
Research Laboratories in Kahuta, Pakistan (Pakistan's main nuclear
weapons laboratory as well as an emerging center for long-range missile
development). Leonard Kahn is best known for his paper: L.R. Kahn,
“Single Sideband Transmission by Envelope Elimination and Restoration,”
Proceedings of the IRE, Vol. 40, July 1952, pp. 803–806., and for his
work on AM stereo. Google somehow doesn't know the difference...

73, Barry WA4VZQ

"Nordic Breeds WA4VZQ" wrote in message
...
"Antonio Vernucci" wrote in message
...
You are both right.

On a 1966 issue of QST magazine, I found the advertisement of "Echoplex"
by Kahn Research Laboratories. It sold for more than 300$, which was not
cheap at those times.

As to Lincomplex, I remember a friend of mine working for Page Europe who
told me having installed Lincomplex on HF transmitters in Africa.

73

Tony I0JX
Rome Italy

Thank you, Tony.

Somehow, I think you are talking about Leonard R. Kahn of Kahn Research
Laboratories in Freeport, Long Island, NY, and not A. Q. Khan of Khan
Research Laboratories in Kahuta, Pakistan (Pakistan's main nuclear weapons
laboratory as well as an emerging center for long-range missile
development). Leonard Kahn is best known for his paper: L.R. Kahn,
“Single Sideband Transmission by Envelope Elimination and Restoration,”
Proceedings of the IRE, Vol. 40, July 1952, pp. 803–806., and for his work
on AM stereo. Google somehow doesn't know the difference...

73, Barry WA4VZQ

Wow, isn't this a super thread? Learned more here in a week of spare
time than 60 years of experiments and reading magazines! Where was
Usenet when we needed it?

Old Chief Lynn, W7LTQ

Somehow, I think you are talking about Leonard R. Kahn of Kahn Research
Laboratories in Freeport, Long Island, NY, and not A. Q. Khan of Khan Research
Laboratories in Kahuta, Pakistan (Pakistan's main nuclear weapons laboratory
as well as an emerging center for long-range missile development). Leonard
Kahn is best known for his paper: L.R. Kahn, “Single Sideband Transmission by
Envelope Elimination and Restoration,” Proceedings of the IRE, Vol. 40, July
1952, pp. 803–806., and for his work on AM stereo. Google somehow doesn't
know the difference...

Yes, it was Leonard Kahn. I have an Kahn SSB adapter for 455-KHz IF receivers.
It employs a great deal of nuvistors. Very complex machine!

73

Tony I0JX