[GreenKeys] news wire photos

[Nick England]

I think the spark-paper method could only be used for black/white
imagery rather than news-quality photos - the resolution wasn't good
enough to provide half-tone images as used to print gray-scale photos
in magazines, etc. For actual gray-scale photos, the receiving paper
was regular light-sensitive photographic paper and a variable
intensity lamp was focused to create the spot on the paper. Lamp
intensity was determined by the incoming AFSK frequency (1500-2300
cps)
After reception, the paper was developed using normal photo chemicals
in a darkroom.

Photos and block diagrams at
http://www.navy-radio.com/rtty-fax.htm

I have an RD-92/UX spark-type receiver that I hope to get working
sometime and drive via ??? - I don't have a transmitter....

cheers,
Nick K4NYW
www.navy-radio.com


On Thu, Jun 16, 2011 at 6:51 PM, Lee Mushel <herbert3 at centurytel.net> wrote:
> Gentlemen:
>
> Once again your notes stir some thoughts that I had forgotten.   But not
> exactly true this time.   You see I happen to have two of the "old" fax
> machines sitting on a shelf in my shed.   I would trade them for a Flex1500
> but anyway, I can't remember what swapfest I got them at but would remind
> you that there was a time when you would see newspaper photos that said they
> were "AP wirephotos."   Yes, that was fax.   Detection and sending was
> relatively simple.   You put the image you wanted to send on a motorized
> drum (it was held in place with a spring).  As the drum rotated, a photocell
> was moved across the drum face.   On the receiving end the image was
> "developed" by a spark from the end of a "wire" you carefully positioned
> over the special paper on an identical drum..  You started the machines and
> after a suitable time to allow the drums to "synchronize" the image was
> sent.