[GreenKeys] Military Mark High to Mark Low change - FWIW

[Dave Horsfall]

On Fri, 8 Mar 2024, John Vendely wrote:

> The reason for various military branches switching from MARK high to 
> MARK low is surely one of the world's great mysteries, on par with the 
> construction of the pyramids.  From an engineering perspective, the 
> choice is entirely arbitrary, but so far as I can see, prior to the U.S. 
> Army's introduction of the MD-522 in 1967, MARK high was the 
> convention.  So why change?  This must have been a bit confusing at 
> times for Army RATT operators, since their existing GRC-26 and GRC-46 
> equipment was MARK high...

Perhaps it may have something to do with higher frequencies being 
attenuated or something?

-- Dave (vk2kfu)