[ARC5] SCR-287 Receiver Spotting.

[Meir Ben-Dror WF2U]

This is exactly how I have my ART-13/BC-348 hooked up – just like in the ARC-8 manual. The spotting switch – or rather “Monitor” as the manual calls it is on a mall bracket under the shelf where the ART-13 is sitting.

 

I have the duplicate of this setup (I just have to make up another set of cables) with the Russian R-807 a.k.a. RSB-70 transmitter with the original Russian dynamotor and the US-9 receiver. In this case, the Russians were a step ahead of the spot switch placement: the key issued with the system had the spotting/monitoring switch on the key itself, and an extra binding post. These keys are pretty rare and only recently I managed to get one to complete the Russian setup as authentically as I can.

 

For illustration, I put a photo I found of the R-807/US-9 setup on an IL-14 aircraft (typical to all the similar radio installations), where the key is also visible – here is the link to the photo in my Dropbox: 

https://www.dropbox.com/s/izzkabbzhmsopi1/tmp-il14-tomasz02.jpg?dl=0

 

The key close-up (not mine, it’s from a Russian museum site – my key doesn’t look as clear as this one – have to redo the faded labels):

https://www.dropbox.com/s/63fokc7l36yoagn/w55b.jpg?dl=0 

 

 

73,

 

Meir, WF2U

Landrum, SC

 

 

 

From: arc5-bounces at mailman.qth.net On Behalf Of Michael Hanz
Sent: Monday, September 28, 2020 11:58 AM
To: J Mcvey <ac2eu at yahoo.com>; ARC-5 <arc5 at mailman.qth.net>
Subject: Re: [ARC5] SCR-287 Receiver Spotting.

 

It's shown in Figure 8-43 of TO 12R2-2ART13-2 (Typical Wiring Diagram for Radio Set AN/ARC-8).  Would that be official enough?  :-)

- Mike  KC4TOS

On 9/28/2020 11:03 AM, J Mcvey via ARC5 wrote:

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  <mailto:arc5 at ix.netcom.com> <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

 

 

 

-- 
Michael Hanz - KC4TOS
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