[ARC5] ARC-5 Question

[Mike Morrow]

> Decided to get an ARC-5 receiver going. Have not played with one since I 
> was a kid back in the 60's. The one I am working on is the 190-550 kC as 
> I want to use it to listen to beacons.

I used a BC-453-B beacon band receiver in the mid 1960s to listen to maritime
Morse operation in the 420 to 520 kHz band, especially 500 kHz.  I continued
monitoring up to the time that maritime Morse went dead on 12 July 1999.  NDBs
are dying out, and not very interesting.  Anything you find can be looked up
at http://www.airnav.com/navaids/ .

>From the limited info you supply, I think you have a BC-453-B receiver from
the USAAF's SCR-274-N, not an R-23* from the USN's AN/ARC-5.

>The issue is that this particular receiver has a 6 pin plug behind the 
>front panel with no center pin.

There was NEVER a 6-pin plug used in any command set receiver.  What you describe
as a 6-pin plug is an 8-pin plug without pins 3 and 8.  Those were often eliminated
on late SCR-274-N receivers as a cost saver, since those pins were never connected
on SCR-274-N receivers.

>The diagram shown in the book is for a 8 pin with center pin.

If your diagram is showing something connected to pin 8, then you are looking
at a schematic for a receiver in the AN/ARC-5 system, not the SCR-274-N system's
BC-453-B that you have.  They have substantial electrical differences, one of
which is only AN/ARC-5 receivers have a connection (HV) to pin 8.

It is surprising how many who have been exposed to these sets for decades do not
realize that there are many significant technical differences between the AN/ARC-5
and the earlier USN ARA/ATA and USAAF SCR-274-N sets.  It's confusing for everyone
when everything gets referred to as an "ARC5".

> Doe anyone have the diagram for the six pin plug to hook up the panel 
> with jack, volume control and BFO switch?

FWIW, the real local adapter panels have no AF jack.  AF was be obtained 
from the AF jacks on the **rack** that mounted the receiver.

Here's the pin-out of the front panel plug, which has all needed information.
Pin 1:  RF gain potentiometer wiper (50K linear taper).
Pin 2:  Ground (Common for pin 1, 4, and 5 circuits).
Pin 3:  No connection.
Pin 4:  Connects to secondary of AF output transformer (ARA and SCR-274-N only).
        Connects 12A6 cathode AF to MX-19 ILS adapter (R-23* and R-24/ARC-5 only).
Pin 5:  Grounded to turn BFO OFF, ungrounded to turn BFO ON.
Pin 6:  Connect to pin 7 to supply LV to filaments and dynamotor.
Pin 7:  Connects to LV from rear rack connector pin 6.
Pin 8:  HV (AN/ARC-5 only).

> Or can someone point me in the right direction?

You can download a manual for the SCR-274-N at:
  http://bama.edebris.com/manuals/military/scr274/

You can download a manual for the LF/MF/HF AN/ARC-5 at:
  http://bama.edebris.com/manuals/military/an-arc5/

Mike / KK5F