[BC] MUTUAL CUE TONES

[Gary Glaenzer]

From: "Tom Spencer" <Radiofreetom at gmail.com>
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>
> And in 2-way land, anything under 300 Hz is "subaudible" - the CTCSS
> tones, forex, are as high as 150 Hz.

the 'standard' tones went to 192.8 ('7A')

then they were extended as high as  250.3.........which cause problems when integrating
less-than-greatly-designed radios into a  system....poor filtering of transmit audio
caused all kinds of problems

the lowest I ever saw used was 'XA' = 71.9 on a VHF repeater / voting system for local
Sheriff's Dept, they used that low, seldom-seen tone to prevent falsing of the receivers
(6 of them)

I recall a couple of old low-band systems that used as high as 6A ( 173.8 ) and 6B (
179.9 )

but most were between 100 and 162.2 Hz

the tones were spaced at 3.5 % intervals   100, 103.5, 107.2, etc as that was considered a
'safe' interval when using the old electro-mechanical 'reed' systems