[GreenKeys] WU Deskfax aka Telefax

[Charles Days]

Joe Duszy?ski <joeduszynski1 at gmail.com mailto:joeduszynski1 at gmail.com >

I used to work with the W-U Deskfax. I had it setup on 6M. A local SK also had one. Though he did not xmit, he did receive. I was using an HA-460 and a highly modified Globe-Scout. I would 'scope monitor (trapezoid) the modulation on the 'scout to aid in DX... An old 3" Millen rack scope...

It was popular for me in '72/'73. I moved and never re-activated the 6M station... Made one DX contact FWIR MN...

Good grief, that was 50ya, are the machines still available? Paper?

Most of the tubes are kind hot audio items now...

There was QST article, but system still lacked a better syncing. I found a way to do a time division syncing and modified both my friends machine and mine. Not an easy mod, re-used all of the relays, even re-stacking contacts to perform the simple logic. I wrote (by hand) a full article for QST but they were reluctant to publish as the machines were "fading away" computers could FAX so much better. I don't know where the article is. Probably in a pile of papers long ago misplaced...

If the machines are not synced, the drums will split the text/image across the page. Once synced for reception, the "National Grid" would keep the 60Hz constant and the page would be O.K. My friend was a good sketch artist so he would send quick sketches via the FAX...

It was good local fun but without anyone else local or DX became boring soon.

AM modulated 2500hz tone. Locals hated it, made a 5khz bandwidth...

The drum signal transmitting has to be inverted, the trick was a short length of Radio-Shack fiber optics. It the signal is not inverted radio reception would be all negative copy. Fill the shack with smoke. When wire connected the central office would invert the signal. I suppose this could be done electrically too...

The stylus is a short length of carbon steel wire, recovered from a cheap wire brush. I kept a spare lamp and photo cell but never needed it...

Ref:

http://madrona.ca/e/deskfax/index.html


Chas

WA1JFD
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