[ARC5] BC-AR-429 and RU-18 Connectors

[Mike Morrow]

>The connectors are different for the RU-18/19 and the earlier RU series...
>The RU-18/19 was a stand-alone receiver, whereas the earlier RU series were
>designed to be paired with a transmitter (GF, GO, GP series).  

No.  "Stand alone" does not mean the receiver was used by itself, with no transmitter.  It means that there was no transmitter integral to the system's design, which then allows the receiver to be paired with any of several transmitter types.  These are also known as liaison receivers, paired with a transmitter of moderate power output.

The RU-2, 3, 4, 5, 6, 10, 11, 12, 18, and 19 are liaison-design systems with no specifically-designated transmitter associated with them.  The transmitters most often paired with these receivers 1932 and later were the GP to GP-7 and the GO to GO-9.

Command set RU systems were the only ones that had a low-power transmitter integral to the system...these were the GF to GF-12.  These were the command set RU models:  GF receiver, RU-2, 3, 3A, 4A, 5A, 7, 8, 9, 13, 14, 15, 16, 17.  (RU-2 and 3 served in both command and liaison systems, and the first receiver used with transmitter GF was also called GF.)

>Seems to me that there are also differences in the bias circuit between the
>RU-18/19 and earlier sets.  The actual wiring differences may be in the
>dynamotor bases.

The AGC bias resistor is in the base of the dynamotor for command set RU receivers, between dynamotor negative terminal and ground.  But liaison set receivers RU-4 and later could use one or two receivers.  If the bias resistor remained in the dyno base, two receivers would produce twice the bias.  So the AGC bias resistor was moved to the individual receiver and the dynamotor negative terminal was connected not to ground, but to a separate pin on each receiver connector that then went to the top of their AGC bias resistor in the receiver.  That way, each receiver gets the right bias, regardless of one or two receivers turned on in the system.

There are other clever and non-obvious design differences in the liaison receiver systems that resulted from the two-receiver design.


>I do think, though, that connectors for the BC-229/429 and the RU series
>through RU-17 may be the same.  But not the 18/19.

No.  The connector on the earliest SCR-*-183 receivers was 7-pin, but by 1935 an 8-pin connector became standard.  Likewise, except for early models before 1935, RU liaison receivers use a 10-pin connector, and command receivers use an 11-pin connector.

I've written a 70-odd page document that discusses these receivers and their transmitters (including all 21 SCR-A*-183/-283 and 14 GF-*/RU-* command sets).  I'm awaiting a new laptop with Windows 10, plus a scanner for 11x17, to finish it.

Mike / KK5F


>From: Robert Eleazer <releazer at earthlink.net>
>   
>Does the BC-AR-429 and RU-18 both use the same electrical connectors?