[ARC5] More ZB

[Robert Eleazer]

The F4U-1 Corsair pilot's manual, the one issued during the latter half of 1944 has the following info on operation of the ARR-2:

1.  Turn the ARR-2 on by switching the Voice-Nav switch on the NAVIG panel to NAV.
2.  Turn CHAN SEL indicator to the channel desired of the 6 channels available.
3.  Turn SENS knob clockwise to obtain comfortable volume level.
4.  Vary pitch or beat note by turning PITCH knob to a comfortable frequency.

So, with the ARR-2 even the pilot of a single seat aircraft was given the ability to switch the received ZB modulation frequency, which was changed by a set schedule as well as the sensitivity of the set.  He also could adjust the "Tone," which I assume was done with a BFO?  Except that I do not recall that the ARR-2 had a BFO, so perhaps it was purely an audio tone. 

The frequency of the ARR-2 is given in the manual as 234 to 258 MC, so they were not taking great pains to hide it, despite the deliberately mismarked receiver dials and the fact that the pilot could not change the frequency.

Also, I find it curious that the APX-1 IFF gear had the usual destruct charges but that the ARR-2 did not.  They must not have been too worrried about the enemy finding out about the ZB system.

Finally, the manual shows a view of the radio controls in the cockpit, including a a tube mounted along the longitudal axis of the aircraft fuselage, and located just above the  radio control boxes, identified as "Navigation Antenna Control."  I have no idea what this could be.  Any ideas?    

Wayne
WB5WSV