Posted to two newsgroups known to be read by likely respondents

The published literature on pre-solid-state electronic analog
multipliers is scant except for production equipment from
analog computer makers (which by now is difficult to locate).
One example of a useful technique is a four quadrant electron
beam multiplier described he

http://dspace.mit.edu/bitstream/1721...9-04734375.pdf

More exotic tubes with curved deflection geometries followed,
however obtaining such tubes is now difficult.

Has anyone at some point tried using sheet-beam deflection
tubes as were used in synchronous detectors and balanced
modulator designs for analog multiplication? I imagine
that using four tubes each driven by quadrant-limited
amplifiers and whose outputs would be biased and summed
with scaling may work within a few percent of input values
based on a quick look at the characteristic curves published
for these tubes. Another option would be to add a magnetic
deflection yoke over the tubes to provide a proportional
steering of the beam sheet in conjunction with the electro-
static deflection (one of the deflection circuits could be
placed in the negative feedback loop of an op-amp) to
reduce the number of tubes required to two (+/-x, y; +/-x, -y).

It wouldn't take long to breadboard a test circuit for
investigation, but knowing past efforts is always welcome.
Surely someone has evaluated using these tubes in this fashion,
even if just for kicks

Michael

On Mon, 31 Mar 2008 14:05:45 -0600, msg wrote:

Posted to two newsgroups known to be read by likely respondents

The published literature on pre-solid-state electronic analog
multipliers is scant except for production equipment from analog
computer makers (which by now is difficult to locate). One example of a
useful technique is a four quadrant electron beam multiplier described
he

http://dspace.mit.edu/bitstream/1721...9-04734375.pdf

More exotic tubes with curved deflection geometries followed, however
obtaining such tubes is now difficult.

Has anyone at some point tried using sheet-beam deflection tubes as were
used in synchronous detectors and balanced modulator designs for analog
multiplication? I imagine that using four tubes each driven by
quadrant-limited amplifiers and whose outputs would be biased and summed
with scaling may work within a few percent of input values based on a
quick look at the characteristic curves published for these tubes.
Another option would be to add a magnetic deflection yoke over the tubes
to provide a proportional steering of the beam sheet in conjunction with
the electro- static deflection (one of the deflection circuits could be
placed in the negative feedback loop of an op-amp) to reduce the number
of tubes required to two (+/-x, y; +/-x, -y).

It wouldn't take long to breadboard a test circuit for investigation,
but knowing past efforts is always welcome. Surely someone has evaluated
using these tubes in this fashion, even if just for kicks

Michael

Two thoughts:

1: x(1 + y) - x(1 - y) = 2xy. Two beam tubes and a couple of op-amps,
and you're in business. Even with tube op-amps you may use less space
and have less grief from offsets than the space of your quadrant-
switching amp and whatever grief you get from same.

2: There are any number of hot-rod DSP chips that'll fit into a T6-1/2
envelope, complete with ADC's, DAC's and a power supply to run off of
6.3VAC. Sealing the glass up without messing up the DSP may be a
challenge, but you could always fudge and use acrylic.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

msg wrote:
Posted to two newsgroups known to be read by likely respondents

The published literature on pre-solid-state electronic analog
multipliers is scant except for production equipment from
analog computer makers (which by now is difficult to locate).
One example of a useful technique is a four quadrant electron
beam multiplier described he

http://dspace.mit.edu/bitstream/1721...9-04734375.pdf

More exotic tubes with curved deflection geometries followed,
however obtaining such tubes is now difficult.

Has anyone at some point tried using sheet-beam deflection
tubes as were used in synchronous detectors and balanced
modulator designs for analog multiplication? I imagine
that using four tubes each driven by quadrant-limited
amplifiers and whose outputs would be biased and summed
with scaling may work within a few percent of input values
based on a quick look at the characteristic curves published
for these tubes. Another option would be to add a magnetic
deflection yoke over the tubes to provide a proportional
steering of the beam sheet in conjunction with the electro-
static deflection (one of the deflection circuits could be
placed in the negative feedback loop of an op-amp) to
reduce the number of tubes required to two (+/-x, y; +/-x, -y).

It wouldn't take long to breadboard a test circuit for
investigation, but knowing past efforts is always welcome.
Surely someone has evaluated using these tubes in this fashion,
even if just for kicks

Michael

Just a memory from tens of years ago:

The 7360 made a decent balanced modulator, but it is,
by definition, extremely sensitive for external electric
and magnetic fields.

--

Tauno Voipio (OH2UG)
tauno voipio (at) iki fi

Tim Wescott wrote:

snip
2: There are any number of hot-rod DSP chips that'll fit into a T6-1/2
envelope, complete with ADC's, DAC's and a power supply to run off of
6.3VAC. Sealing the glass up without messing up the DSP may be a
challenge, but you could always fudge and use acrylic.


This would be a new acme in solid-state (Fetron-style) replacements

Michael

Jimmie D wrote:
Just a memory from tens of years ago:

The 7360 made a decent balanced modulator, but it is,
by definition, extremely sensitive for external electric
and magnetic fields.

--

Tauno Voipio (OH2UG)
tauno voipio (at) iki fi

You just answered a problem thats had been nagging me for over 30 years.
Now I know why the SSB transmitter I built had such an annoying hum in it.

I never thought about it being affected by a magnetic field.
=========================================
For that reason in 1970s transceivers like Yaesu FT-400/401 the 7360
used as balanced modulator was 'packed' in a tight metal screen bonded
to chassis.

Frank GM0CSZ / KN6WH

Jimmie D wrote:
Just a memory from tens of years ago:

The 7360 made a decent balanced modulator, but it is,
by definition, extremely sensitive for external electric
and magnetic fields.

--

Tauno Voipio (OH2UG)
tauno voipio (at) iki fi


You just answered a problem thats had been nagging me for over 30 years.
Now I know why the SSB transmitter I built had such an annoying hum in it.

I never thought about it being affected by a magnetic field.

Jimmie



Think about a magnetically-deflected TV picture tube.

I noticed the problem, when my Eico 753 (around 1968) worked
fine when the power supply was on the right side, but had
a rough hum reported by other stations, if the power supply
box was moved to the other flank.

--

Tauno Voipio (OH2UG)