[ARC5] How Secret Was the ZB/YG System? Not much!

[Mike Morrow]

Jay wrote of the ZB/YG homing system:

>...why so secret? the Eastern Bloc knew just about all
>we knew technology-wise.

The ZB/YG system was never SECRET...not even close...not even when WWII was in progress.

In the WWII-era, levels of classification in the US Armed Forces ranged from RESTRICTED to CONFIDENTIAL to SECRET to TOP SECRET.  The classification of the equipment manuals is an indication of how secret the equipment is.  Before and even in the midst of WWII, the classification of the ZB-*, AN/ARR-1, and AN/ARR-2 equipment manuals was only RESTRICTED.  That is a very low level of classification...even the SCR-*-183 and RU/GF were RESTRICTED.  The homing decode cards for the ZB/YG system were often at the next higher classification of CONFIDENTIAL, but only when filled in.  

Manuals for WWII USN IFF systems like the AN/APX-1, -2, and -8 were CONFIDENTIAL, with red covers on the manuals.  

After WWII the RESTRICTED classification was eliminated in the US.  Manuals for the ZB/YG homing system were completely declassified.

Mike / KK5F