[Milsurplus] Aircraft comm/nav specs

[Jack Antonio]

During WWII, channel spacing for the VHF sets was 180 kc, starting
at 100.08 Mc.  The crystal frequencies were on 10 kc spacings, starting
at 5560, then 5570 and on up.  126.18 was a widespread common channel,
with a fundamental of 7010, which is why there are a lot of surplus
CR-1A/AR crystals on 7010 floating around.

I have read that even at 180kc spacing, there were some issues with
frequency stability in the early days. I am pretty sure that the
improvements in stability came about with improvements in crystal
manufacture.

I don't know when the move to 100kc spacing came, sometime in the
early 50s I would guess.

Jack Antonio WA7DIA/4