[Milsurplus] ARB, RU, ZB

[Mike Morrow]

I wrote:

>I guess don't understand this. The ARB is considerably longer (and
>heavier) than the RU (or the GF), and is 28 vdc only.

Mike Hanz wrote:

>Not sure of the definition of 'considerably' employed here.

I was considering only the size of the two boxes.  The case of the ARB, 16 inches long, is about three inches longer than the case of the RU.  When the ZB homing unit is mounted on top of the ARB, there's a considerable amount of space fore and aft the ZB, while the ZB on the RU is almost the same length as the RU below it.

>The author responsible for the ARB and ATB 'introductory' article
>in the Radio and Sound Bulletin of 1 Oct 1942 that "The ARB will mock 
>up into approximately the same space as the RU."

And I see that is correct, because the shock mount for the RU extends the total length of the RU footprint to within a half inch of the ARB footprint.  Still, visually, the RU *seems* to me to be considerably smaller than the ARB even though the two units occupy the about same amount of real estate.

I keep mentioning the ZB and the ARB, because the ZB was such an important system that seldom gets the recognition that it deserves.  The ZB is so easy to fit to the ARB that it surprises me that the ARB manual doesn't explicitly detail the installation...IIRC, those ZB mounting posts on the top of the ARB case go unexplained in the ARB manual.  It's clever how the ARB control box allows switching to the ZB simply by selecting the broadcast band in HOMING (loop) mode, and allows normal broadcast band use by selecting that band in COMMUNICATIONS (non-loop) mode.  Those awkward ZB control and relay boxes and associated cables are *not* used.

Mike / KK5F