[ARC5] SCR-522: Rethinking The Old Gal

[Jack Antonio]

> 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:

In the earlier versions of the SCR-522, the relay scheme included
support for the RC-96 "Pip Squeak".  This was eliminated in later 
versions which meant fewer relays in the transmitter.

However, the Byzantine switching scheme from receive to transmit
remained.

And this is one of those sets, where you can't have too many
versions of the manual, in going through my set, I found the
information needed across multiple manuals. Of course, this
could be the result of post-military chassis swapping.

There is a manual for the SCR-522, TM11-509, which describes the
installation into ground vehicles and makes little or no mention
of aircraft usage.

Jack Antonio
WA7DIA

> "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
> 
>