[GreenKeys] Fwd: The Flying White House 1947

[Duncan Brown]

I just received the original photo from Don - it is going to the AWA 
Museum.  Looking at the photo with a magnifying glass, I can see a 
little more detail than was available on the scans.

The unit behind the operator's head is definitely a diversity FSK 
receiving converter.  I can make out the meter switch markings and they 
are things like "Chann B"; "Chann A + B"; "Polar"; "Neutral"; etc.  I 
was then able to identify the converter as of the FRF & CV-31/TRA-7 
family (although a slightly different configuration).

Below the CV-31 is a BC-348 receiver (must have been another one unless 
they were using one of the ARC-5 receivers for diversity).

Below the BC-348, I can just make out another chassis with a large shiny 
dial.  This might be the FSK modulator - something like the O-79/TRA-7 
used (along with the CV-31) in the AN/MRC-2 in this time period (and 
later in the early AN/GRC-26s).  So maybe the ART-13 was running true 
FSK (but where is the other coax - on the other side of the ART-13?)

In looking up the O-79, I came across an interesting document: "Military 
Teletypewriter Systems of World War II" at  
http://www.nonstopsystems.com/radio/article-AIEE-1948.pdf
(I was surprised to learn that there was some Multi-Channel, Independent 
Sideband, radio teletype used on high volume circuits during WWII and 
that the Bell system had been using it prior to WWII.)

On the front of the SIGNIN, between the keyboard and paper tape reel is 
something that looks like a perforated tape reader.  So there must have 
been an "Iron Horse"/GPE perforator somewhere.

Have fun,

Duncan