[Milsurplus] ZB-2 connection to the ARB

[Mike Morrow]

The ZB homing system, when used with the RU or ARA series of receivers, requires the ZB homing adapter, the ZB antenna relay switching unit, the small ZB control box, and a mildly cumbersome set of plugs and cables to put it all together.

I just read on Mike Hanz's excellent (http://aafradio.org), under the DOCS section, some interesting ARB and ZB info.  The US Navy "Radio & Sound Bulletin No. 8" dated 1 October 1942, describes the ARB/ATB sets.  The article says that when the ARB is used with the ZB homing adapter, no ZB antenna relay or control box is required.  This is because the ARB has a relay to select the loop antenna input automatically when HOMING BAND A or HOMING BAND B is selected on the ARB control box.  Thus, it appears that the only connections between the ARB and ZB would be a three-wire filament/HV power cable, plus a simple RF connection from the ZB PL-259 output to the ARB loop terminals.  I've always considered the ARB loop terminals as intended to support use of a DU LF/MF loop.  But such a loop would never be utilized when a ZB homing system was available.  The ARB was always mechanically adapted to support a ZB with those ZB mounting clip posts on the top of the cabinet, but I never realized that the ARB was also designed to *electrically* accomodate a ZB with minimum additional fuss.

The ARB manual does *not* point out this feature.  Has anyone come across a USN diagram documenting the details of the ZB connection to the ARB?  Is such official documentation unlikely, perhaps because the ZB was replaced by the AN/ARR-2 not too long after the ARB was deployed in quantity?

Mike / KK5F