[GreenKeys] Re: Teletype Model 12KSR

[Don Robert House]

It is good to hear of the Model 12.  Ours is awaiting restoration in  
Oceanside, California.  I will send some photos of it to anyone who  
would like to see them.  It is important to remember that the machine  
was the first commercial Teletype success.  The first customer was  
the Alton Railway but the first successful deployment was with the  
Associated Press.

Don


On 5 Apr 2006, at 3:53 PM, Doug Alderdice wrote:

At 04:14 PM 4/5/2006 -0400, Charles Ring W3NU wrote:
> Is there a really good explanation online of how the model 12  
> worked? Decades ago I knew more about it than i do now but not  
> really a lot. Multiple selector magnets and a receiving distributor  
> are things I do remember. I know that many ham radio operators used  
> them (serial) into the 60's. I also know that the Chicago police  
> used them into the 50's but i don't know why or what kind of  
> network. I also know that they often ran at 40wpm but they must  
> have been capable of 60 since that is the only speed hams were  
> allowed to use back then.

"Ask the man who owns one"... and I'll try to comment a bit on my  
Model 12.

Yes, the Model 12 has multiple selector magnets, one for each bit  
element, plus a "print" magnet, which is fired from the distributor  
once the character has been received and set up on the selector magnets.

The configuration of the Model 12 is interesting, to say the least.   
The typing unit looks like an old Underwood upright typewriter, and  
has a moving platen.  The typing unit contains only the drive motor,  
selector magnets and the requisite type bars and levers.  The  
keyboard is in a separate unit and contains a motor, receiving  
distributor and keyboard.  The actual keyboard resembles that of a  
Model 14/15.  The typing unit and keyboard connect together on the  
special table that a Model 12 comes with (or should come with) that  
has a series of slide contacts.  The keyboard and the typing unit can  
each be easily swapped on and off the table.  The table also contains  
a polar relay for serial use, and to switch the high voltage magnet  
current since each magnet needs a good 100 mils or more.  There is a  
rather ugly sheet metal cover that goes over the whole mess, giving  
the machine a rather large, plain, boxy look.  Though, the cover is  
needed since the machine makes a fair bit of noise.  In the old RTTY  
primer book put out by Wayne Greene in the early 60s, the Model 12's  
operating noise is characterized as "sounding like a cement mixer"  
and it is an accurate description!

I have some pictures of my Model 12 on this page: http:// 
mysite.verizon.net/dalderdi/telegrph/model12.htm from back when I  
started to rewire the table.  It had come from its previous owner (a  
ham) who had put together a tube-type electronic keyer for the thing  
to reduce the massive RFI that a Model 12 (with all those selector  
magnets) generates.  It was the modification-du-jour in the 50s and  
60s to do this with a Model 12 so you had a chance of hearing the  
signal you were trying to print!  I got the Model 12 with the keyer,  
but the keyer was in bad shape with no schematics and the wiring in  
the keyer was dicey at best so I decided to put the 12 back to  
factory wiring, as it were.  I started into it and started the page  
above and then lost momentum on the project for whatever reason,  
though the construction of my telephone step switch started later  
that same year had something to do with that.  Too many hobbies, not  
enough time!

Anyway, on the page above in the last photo there's a decent head-on  
shot of my '12, and you can see the separate receiving and typing  
unit motors and the receiving distributor on the keyboard base.  I  
should take some pix of it with my new digital camera and post it  
since more of the machine's details will can be seen with the higher  
resolution camera.

The few times that I have run my 12, I would say that it can run 60  
WPM just barely.  Granted, my unit is quite elderly at this point and  
needs a really good cleaning and lube, but it struggled to keep up  
with my typing on the keyboard.  I haven't operated it on the line  
with another teletype machine yet.  Before I do that I need to rewire  
the keyboard base, which appears to have a problem.  The previous  
owner rewired it and it is very neatly done, but he messed up  
something in one of the bit leads so it doesn't operate quite right  
or accurately at this point.

I need to get back to working on that now that my step switch has  
been up & running for some time now, http://mysite.verizon.net/ 
dalderdi/phones/sxs.htm.

73,

Doug, KA2WFT



_______________________________________________
GreenKeys mailing list
GreenKeys at mailman.qth.net
http://mailman.qth.net/mailman/listinfo/greenkeys