[ARC5] Use (or Non-use) of the ZB (or AN/ARR-1) Control Box and Antenna Switch

[Lloyd Godsey]

Long as we are on the subject:
I have a decent ZB-3 sitting here, Got some crud on the lid dishwasher 
didn't take off.
Inside real nice.
Those 954's and acorn sockets would sure work good in one of my projects.
For sale or trade.
Make offer.


Thanx
Lloyd Godsey KK7IZ
kk7iz at cox.net
480-620-7145
http://www.lloydsdipsydumpster.com/
http://antiqueradioarchives.com/
Skype: lloyd.godsey

-----Original Message----- 
From: Mike Morrow
Sent: Saturday, November 05, 2011 3:06 PM
To: arc5 at mailman.qth.net ; milsurplus at mailman.qth.net
Subject: [ARC5] Use (or Non-use) of the ZB (or AN/ARR-1) Control Box and 
Antenna Switch

The well-known ZB-series VHF homing adapters(and the AN/ARR-1 JAN
version) had a pilot's control box and an external antenna switch
as accessories.  The antenna switch disconnects the associated
broadcast band receiver's antenna terminal from the aircraft's
wire antenna and connects it to the output of the homing adapter.
The pilot's control box has a HOMING-COMM switch that controls the
antenna switch, plus a DISTANT-LOCAL switch that adjusts the RF
sensitivity of the homing adapter.

It is well-documented that the ARB receiver was designed to mount
a ZB-*, provide it power from an accessory connector on the front
of the ZB-*, and connect to the output of the ZB-* through the
ARB's loop antenna terminals and associated switch.  Mike Hanz's
site at http://aafradio.org/docs/atb-arb.html has the description
from the USN Radio & Sound Bulletin No. 8, 1 October 1942 which
boasts the resulting elimination of the ZB antenna switch and
pilot's control box.  Apparently there was no real value in dropping
sensitivity of the ZB, for that is the only loss of function that
arises from the simplified ARB/ZB installation.

Only the ZB unit, a three-conductor power cable from the ARB to
the ZB, and a RF connection from the ZB to the ARB's LOOP terminals
are required.  To select the ARB/ZB combo, the operator selects the
560 to 1600 HOMING band on the ARB control box and tunes to the
BCB output frequency of the ZB.  If the operator wishes to use that
band normally, he selects the 560 to 1600 COMMUNICATION band on the
ARB control box to swap the ARB input to the normal antenna connection.

The same philosophy of interface simplification appears to have been
utilized in ARA with ZB installations.  The BCB Cxx-46145 receiver
could replace the beacon-band Cxx-46129 in the receiver rack.  The
ZB could get power through a three-conductor cable between it and
the Cxx-62036 power adapter panel that is standard on all ARA
Cxx-46145 BCB receivers.  No antenna switch is needed.  Use with
the homing adapter is the only reason for the BCB receiver in
most such command set installations, so the Cxx-46145 could be
permanently connected to the output of the ZB homing adapter.  When
the ZB homing system is required, the pilot needs only select the
ARA audio bus (A or B) that has the output of BCB receiver.

John/W4THQ reported in June 2010 on the radio installation aboard
a recovered F6F-3 that had been lost in Lake Michigan in January,
1945.  The aircraft carried an ARA/ATA with ZB-3, among other
things.  When John last reported, no ZB antenna switch or pilot's
control box had been found, while all other expected controls
and other accessories for all the radio gear had been found and
listed.  This supports the system configuration that makes most
sense.  I'd like someday to get positive confirmation of the use
of the ZB without the antenna switch and pilot's control box.
Any new info John?

The exact same configuration is applicable to the AN/ARR-1 when
used with the SCR-274-N.

The "improved ZB" AN/ARR-2 would have been utilized with the
AN/ARC-5 command set.

I have a Handbook of Flight Operating Instructions (the "dash 1")
for the B-29, B-29A, and B-29B.  Some of these aircraft carried the
AN/ARR-1 ZB-homing adapter.  The AN/ARR-1 output was directed to
the ANT connection of the AN/ARN-7 ADF receiver.  The VHF homing
system usage instructions tell the operator to select ANT on the
ADF control box, select CW mode, and tune the appropriate frequency
in the 410 to 850 KC band.

Bottom Line:  There would have been no value to including the
ZB or AN/ARR-1 antenna switch and pilot's control box when using
the homing adapter with the ARA/ATA, ARB/ATB, or SCR-274-N.
For that matter, even the old RU-* could have been connected to
the ZB through the RU's loop terminals, eliminating these accessories
even there.

Mike / KK5F
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