[ARC5] SCR-522: Rethinking The Old Gal

[David Stinson]

On 4/26/2020 10:31 AM, Mike Morrow wrote:
 >

 > IMHO the SCR-522-A was the MOST important aircraft
 >command set on any frequency used by any armed service
 >of any nation during WWII..
 >Unfortunately, its horrific complex "Rube Goldberg" push-button
 >mechanical nightmare BC-602-B control box inspired
 >similar control box abominations like
 >the C-118/ARC-3 and C-30/ARC-5. :-)

It's not just the 602 control box.  The channel switching to the
back-a**-wards use of relays ( Antenna and B+ switch relays are
picked in receive and unpicked during TX!) to needless junction boxes
that added nothing but expense and complexity (wisely dispensed-with
in U.S. installations).  There's a relay you pick by providing ground,
so it can close a contact and provide ground to another terminal:
"Do WHAT?"  A *balanced," magnetic mic audio input; you
need an external adaptor to use a standard unbalanced carbon mike.
The manuals and schematics can't agree on the standard for showing
those relays.  Some appear to be picked, some not.  I pulled what little
hair I had left trying to cypher-out the PTT sequence in this thing to
correct a cabling error.  I think Einstein could have understood the 
diagrams
and the keying sequence- if he was having a really good day.
For a bonus, there are three different versions of the receiver with 
different
Mongolian Goat-Script and Atlantian Hyroglyphs in their individual diagrams.
Rube Goldberg would have given-up on
this electro-mechanical robo-train wreck.  I don't think the people who
designed it could explain it.

But all that being said, it is not hard to service and, once one finally 
solves
the puzzles and mysteries- like the "plain girl" at the dance, the set
has charms to reward the effort.
As Mike suggested- it was a very important and historic step in
aviation comms evolution, thus worth the effort to preserve.
When done, it will be fully operational in as-designed configuration.
If I actually live long enough to build a REAL shack where I can display
and operate my treasures, it will look awesome next to it's direct-
lineage "grandfather," the operating U.K TR9-D.

  The receiver is crystaled for the local AWOS
(Automated Weather Observation Station),
DFW Departure, the local UNICOM and for chat-around freq 123.45 MC.
The transmitter is also "Go" on two channels.   Of course, it would be
illegal and un-hammish to exchange greetings with private pilots on
this set, comment on the lovely weather and wish them a safe flight,
and hear their kind and cheerful replies.
One should never do such a thing.  Heavens, no.  Perish the thought....

GL OM ES 73 DE Dave AB5S


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