[Milsurplus] [die at dieconsulting.com: Re: WWII Facsmile]

[David I. Emery]

On Thu, Jun 30, 2011 at 07:28:58AM -0400, C.Whitaker wrote:
> de WB2CPN
> Now, here's what, having spent a good part
> of my time with USAF receiving faxes at the
> Weather Central at Andrews AFB in 1949
> and other places later, here it is:
> The TXC-1 has a small stylus that burns the
> cover from the fax paper that's on the drum.
> We used two kinds of paper, Teledeltos and
> not-teledeltos.  Teledeltos stunk when it was used,
> but it could be copied in a gelatin copy machine.
> The other paper was also white, but had a thin
> coating of starch.  It did not smell.   It was all
> 12 by 18 size.  Drums on SSB radio circuits
> turned at 60 RPM, drums on landline circuits
> turned at 120 RPM.   Trivia:  At the HF receiver
> site, where the operator had to keep a very
> close eye on the incoming signal, the plain paper
> was used.  The fax signal then went to the weather
> people nearby who used Teledeltos to meet their
> needs.  When the weather people had a problem
> with their machines, we copied with Teledeltos,
> and sent it to them by courier.
> The TXC-1 could send and receive shades of
> gray in black and white, but weather maps were
> all black and white.

	Many many moons ago when I was in HS in the early 60s I had one
of those stylus machines (initially incomplete scrap parts of one and
quite a bit later a complete working one as well) that I used to receive
HF radio weather faxes.   Both came from mil surplus channels.

	I obtained some paper somewhere - too long ago to remember
exactly where but it I think it was also from surplus somehow.   It was
about 12 by 18... and grayish white coated and very heavy and dense
as a package of sheets.   I do remember (once reminded of the spelling)
the name Teledeltos, but whether my paper was that kind or not I forget.
I don't remember much in the way of commercial branding on the packages
but that was probably par for the course for (ex)military supplies.

	Not sure if either machine was a TXC-1 or something slightly
later but it did have a distinctive meter on the control panel below the
turning drum that could be set to monitor various things, some of which
fluctuated in tune with the turning drum.

	From a circuit standpoint the drive to the tungsten stylus was
pretty simple IIRC, mostly just an audio power stage with a high voltage
transformer output that amplified the DSB audio signal from the line
input with some kind of clipper ahead of it that allowed audio below a
certain threshold to be not amplified at all.

	For HF reception one needed a FSK (or really FM to AM converter)
fax "converter" that decoded the FM video and used it to remodulate
a fixed frequency audio carrier as DSB AM.


-- 
  Dave Emery N1PRE/AE, die at dieconsulting.com  DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in 
celebration of what could have been, but wasn't and is not to be now either."