[GreenKeys] teleprinter?

[Duncan Brown]

On 02-Jul-21 11:35, W2HX wrote:
>
> Anyone recognize this 
> teleprinter?https://en.wikipedia.org/wiki/Arthur_A._Collins#/media/File:Collins_Airborne_Station.jpg 
> <https://en.wikipedia.org/wiki/Arthur_A._Collins#/media/File:Collins_Airborne_Station.jpg>
>
>  73 Eugene W2HX
>

I was off-line last weekend and still trying to get caught up with my email.

I came across this picture a few years ago. The Collins Airborne Station 
looks like an AN/ASC-12. See Collins description attached. The TTY looks 
like the MITE ASR, AN/TGC-29. I found a write-up about the Collins & 
MITE gear at http://www.hypertools.com/pix/pix.html. That URL doesn't 
work anymore (but sounds familiar - someone here on Greenkeys?) but I 
saved the write-up and it is enclosed as "AN TGC-15.txt"

The MITEs were hard to work on because they were so small and densely 
packed.  Most of the pictures I've seen of them were in aircraft, where 
weight & space were paramount.  Doomsday plane picture enclosed.

The US Signal Corps almost used them in the AN/GRC-122/-142. Enclosed is 
a page out of a Signal Corps document (thanks to Ron Boltz) showing a 
(prototype?) "AN/GRC-142" with the AN/TGC-29 & AN/TGC-14. As an Army TTY 
repairman, I'm thankful that the stock GRC-122/-142 units used the TT-76 
& TT-98s!

Have fun,

Duncan
K2OEQ

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http://www.hypertools.com/pix/pix.html

ASC-12---page-1
Now this has got to be a very limited production item. The ASC-12 was used to add comms capability to an aircraft when the mission required more radio than was built into the aircraft originally. It looks as if the unit pictured in this brochure is the same one that is in the photo shown three pages down. 

ASC-12---page-2
The text mentions a AN/TGC-15(XN-4) teleprinter. The photo shows a variant of MITE ASR teleprinter. The MITE ASR in the photo is different from the usual MITE ASR in that there is a hinged panel just above and to the right of the slide-out keyboard. This hinged panel is missing in the common MITE ASR and the TGC-29 MITE tactical ASR units. My guess is that this MITE was designed for crypto use, I have no idea what is behind this hinged panel. 

ASC-12---page-3
The word 'matrix' shows up at several places in the block diagram. It describes the interconnect scheme used between the audio section (operator & interphone & modems) and the HF radio. First guess is that the audio matrix is implemented in the 452S-6 and a 452S-5 units.

ASC-12---pic-1_T
What's behind door #1? A stack of URG-1 gear. Top row, the left two boxes appear to be a 452S-6 and a 452S-5 - if I read the number correctly then both are described as a 'relay unit' but beyond that they are a mystery to me - could be they have to do with the implementation of the modem switching matrix. Then a TE-204A-4 modem, and three more modems, a 700B-4 and two 700B-2 units. Next row down is the HF receiver section - a 789R-1 IF translator, a 618Z-4 RF translator, and a 635V-1 preselector. The bottom row in the rack is the HF transmitter section - left box is unknown, next is a 789T-1 IF translator, a 618Z-4 RF translator, and the 548L-4A 1 KW RF power amp. On the bottom deck is a hefty ventilation fan, an ARC-51 and an ARC-54. 

ASC-12---pic-2_T
This second ASC-12 is a bit different - no MITE ASR, just a garden-variety non-tactical MITE KSR. Note the tail number on the engraved panel - 58-6970. This tail number belongs to a USAF VC-137B (Boeing 707-153B) which saw service as Air Force 1. US Presidents Eisenhower, Kennedy, Johnson, and Nixon all flew on this plane. For more info on the tail number, click here. Nice elapsed-time clock by Breitling-Wakmann
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