[ARC5] SCR-287 Receiver Spotting.

[J Mcvey]

 The switch in the second "flight deck" picture looks like an "innovation" rather than a official part of the system.Is the switch included in the official  SCR-287 system manual?Interesting...

    On Monday, September 28, 2020, 9:35:22 AM EDT, David Stinson <arc5 at ix.netcom.com> wrote:  
 
 Having a hard time finding what I did with my
SCR-287 documents box.   The switch used to
keep the 348 "live" during transmit was designated
a "Monitor" switch.  It was usually installed right
next to the 348, though you find them placed
in small panels as well- seems to have been a
"where ever it ain't in the way" decision from
install to install.  Most of the B-17 recreations
of Radio Op positions omit this switch
(and just about everything else).

Pins 21 and 22 on the PL-64 are a NC contact
on the keying relay, designated "Receiver Control"
or "Key Relay" depending on which diagram
you have.  This contact removes high voltage
from stages in the 348 to provide muting.
The "Monitor" switch shorts this pair to
keep the receiver alive during transmit
for netting.

Here's a couple of poor pictures of original
installations and one of my SCR-287.
In one, the switch is just right of the 348.
In the other, the switch is mounted on a
small panel to the left.  My 287's switch
is on a panel up and right from the 348.

https://photos.app.goo.gl/igfRP5nNA3qgxBxj6
https://photos.app.goo.gl/9MmdTBj7gTWGzFbM9
https://photos.app.goo.gl/psX8aBR52PfDcsNN9

73 Dave AB5S


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