[GreenKeys] Fwd: Re: Early Fax Machine/ NBC Radio News on the Hour

[Bruce Gentry]

-------- Forwarded Message --------
Subject: 	Re: [GreenKeys] Early Fax Machine/ NBC Radio News on the Hour
Date: 	Mon, 2 Jan 2017 14:13:18 -0500
From: 	Bruce Gentry <ka2ivy at verizon.net>
To: 	Sheldon Daitch <SDAITCH at bbg.gov>



My mother was a telephone operator in San Francisco in the late 1940s, 
and often handled fax calls. There were favored trancontinental circuits 
that would be used when possible. One other detail was a physical block 
the operator would put on the switchboard keys of a circuit handling a 
fax so there would be minimum chance of disruption. In the time of my 
war, fax machines in the Air Force were usually maintained by ground 
radio technicians like me, and good circuits were a serious problem in 
southest Asia. Although we were an Air Force base, our outside lines 
were provided by the Army Stratcom service. Usually the quality was 
nominally satisfactory, but often noise and dropouts caused serious 
problems. 99% of the transmissions were weather maps, so some 
transmission defects could be tolerated or might not even be seen. The 
machines we normally used were built by Litton and used magnetic writing 
heads on a toothed belt to scan across a sheet of carbon paper onto 
white paper beneath. Keeping the heads and their contacts and rollers 
clean and operating freely was a constant pain. We did have a TXC-1 as 
well, used on occasion.

      Bruce Gentry, KA2IVY

On 1/2/17 12:58 PM, Sheldon Daitch wrote:
>
> The AP wirephoto circuit was still amplitude tone modulated at least 
> up until the 1980s.
>
> I think the same for the UPI wirephoto network.
>
> I don't remember the frequencies used and I am almost sure the two 
> networks had different tone standards.
>
> The AP (and I would guess the UPI) system started each photo with a 
> tone set up, I think the maximum level, but I don't know if that was 
> for black or white.  Then the system sent a staircase of tones from 
> the lowest level to the highest level, that would set up the machine 
> for the black and white extremes, then the photo scan information was 
> sent.  Of couirse, this long initial tone also brought the photo 
> receiver out of idle status.
>
> The system relied on the level stability of the AT&T network which 
> apparently was satisfactory for the most part.  Level shift would show 
> up as changes in the black level in the photo.
>
> The reason I don't think the two wirephoto networks used the same tone 
> frequencies is that when I was with the AP out of Raleigh, I went to a 
> newspaper which was having wirephoto machine problems.  I did the 
> usual checks of the machine, the newer AP laserphoto machines (made by 
> Harris) and did a maintenance cleanup of the heater/developer shoe and 
> put the unit back in service.  I waited for several photo cycles but 
> the unit never printed out a photo.
>
> At first, I wasn't paying a lot of attention to the wirephoto audio 
> chatter, the talkup for the photos and then I realized the voices 
> didn't seem to be the right folks and the locations mentioned weren't 
> the usual AP bureaus. Turned out that AT&T in Raleigh had patched the 
> wirephoto circuit to the newspaper to the UPI network instead of the 
> AP network.  Changing the patch to the correct circuit, and yep, the 
> machine came to life.
>
> 73
>
> Sheldon
>
>
>
> ------------------------------------------------------------------------
> *From:* GreenKeys <greenkeys-bounces at mailman.qth.net> on behalf of 
> Bruce Gentry <ka2ivy at verizon.net>
> *Sent:* Friday, December 30, 2016 7:58 AM
> *To:* greenkeys at mailman.qth.net
> *Subject:* Re: [GreenKeys] Early Fax Machine/ NBC Radio News on the Hour
> Into the early 1960s the tone of a fax machine with a tympani roll in
> the background was used as the intro to the hourly news report on NBC
> radio. As best I can recall, the tone was amplitude modulated. However,
> I have seen  another wirephoto machine that used FM audio tone.
> Probably from the 50s or 60s, it was all tube and used a tuning fork
> oscillator to drive the drum motor.
>
> / <http://www.qsl.net/donate.html>
>
>



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20170102/3ff09f08/attachment.html>