"ARC-5" Command Set Transmitter Pin-outs

[David Stinson]

(Copied to the list for general information)

One of the "good guys" wrote:
 Dave -

> You said that the Navy Transmitters were different beasts.
> I assume that means that the power connector on the back of this
> transmitter isn't the same as the ARC-5....

The Command Set transmitters come in several "flavors,"
all of which people sometimes incorrectly lump under "ARC-5."
The ATA/ARA units and SCR-274N (BC-4xx, -696) units are
nearly electrically identical and will fit and work
in each other's racks.  The later AN/ARC-5 units
are different in several ways,
including a different power plug with different pin-outs.
----------------
Transmitter Plug Pin-out:
(Note: If yours has an octal socket or anything
 other then the 7-pin Mica connector,
 then it's a modification and all bets are off.)

For AN/ARC-5-
There are seven pins.  The pin in the center is
pin #7.  Locate the pin that is grounded
to the chassis.  This is pin #4.
Count the others *clockwise* around accordingly.

1.  No Connection
2.  +200VDC for the Osc. (needs to be right for stability).
3.  Keying Relay (ground to key).
4.  Ground.
5.  A+ 24-28 VDC.
6.  PA Screen Voltage (use 20K 5W dropping res. from B+).
7.  PA Plate B+ Voltage +550VDC (not critical)

For ATA/ARA and SCR-274N:
There are seven pins.
The pin in the center is pin #7.
Locate the pin that is grounded
to the chassis.  This is pin #1.
Count the others *clockwise* around accordingly.

1.  Ground
2.  Test point for PA grid current.
3.  +200VDC for the Osc. (needs to be right for stability).
4.  PA Screen Voltage (use 20K 5W dropping res. from B+).
5.  Keying Relay (ground to key).
6.  A+ 24-28 VDC.
7.  PA Plate B+ Voltage +550VDC (not critical).
----------------------------

73 OM DE Dave Stinson AB5S
arc5 at ix.netcom.com

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