[GreenKeys] Kleinschmidt, Morkrum, M-K, M14-TP, and other early stuff

[Doug Alderdice]

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