[ARC5] [Milsurplus] Interesting ARC-3

[Jack Antonio]

On 11/27/2017 10:32 AM, jeepp wrote:
> Particularly interesting.  A lot, arguably tens of thousands, of xtals 
> went obsolete when the RTCA and ARINC first instituted 100 kHz VHF 
> comm channel spacing.  I remember that the USAF tower common freq.  in 
> the 40s and 50s was 126.18.

Out of curiosity, when did this happen, and also, *how* did it happen. 
Was it a gradual phase in of the new plan, or
was there a hard cut off date when the transition occurred? Did it 
happen at same time in military and civilian service?
Was it driven by the military, or by the civilian side of the aviation 
community?

Along the same lines, was there a "drop dead" date after which the tower 
LF(278kc), aircraft HF(3105/3023.5kc) system
would no longer be used?

Jack Antonio
WA7DIA