[ARC5] Is guess this for an RU?

[Mike Hanz]

On 6/3/2011 9:37 PM, Mike Morrow wrote:
> A dual-band coil set like that shown in the auction, remotely
> switched through a spline, allowed the RU-16/17 to provide communications
> and homing service.

Mike presented an excellent summary on the intent of the dual band coil 
box.  I have never seen one of the square spline drives in the flesh, so 
when AB5S was thinking about including his beautiful and *very* complete 
SCR-183 as one of his displays for the Dallas HamCom this month, I 
started fabricating the pieces for him to go from the dual band MC-135 
(Navy ***-23054 equivalent for the RU) hi/low band control to the coil 
box.  Turned out not to be quite so straightforward.  For example, the 
MC-135 that I was using to design the fittings had a slightly oversize 
female socket, so naturally a standard 1/4" square shaft fit it 
perfectly.  Subsequent trials with other coil boxes showed that most of 
the sockets were *exactly* 1/4", requiring a drive tip that was slightly 
smaller to interface consistently. :'(   Anyway, the story with photos 
is about halfway down the page at 
http://aafradio.org/garajmahal/flex_drive_cables.html for those with a 
strong stomach...:-)    The good news is that you can use a normal ARC-5 
type tuning cable to make up this band change cable without needing one 
of the infernal command set spline adapters that are increasingly rare.

73,
Mike  KC4TOS