[Elecraft] Re. Experiment: how much PL tone deviation is required to reliably key repeaters?

[Ian Greenshields]

In the UK, the requirements are fairly clearly defined as part of the
licence conditions for the repeater:

access:The repeater must not be carrier accessed directly from "cold" and
adequate immunity must be provided against access by speech or noise.
Initial access shall, as a minimum, be by a carrier modulated with a CTCSS
tone of the frequency stated on the Notice of Variation.
The CTCSS detector for this purpose, should respond to only that tone, when
it is present for less than 1 second at a deviation of 10% or less of the
appropriate maximum i.e. +/-500Hz for 25kHz units and +/-250Hz for 12.5kHz
units.
In addition, but optionally, access may be by a tone "burst" of 1750Hz plus
or minus 25Hz at a deviation of 50% or less. The acceptance time of the
tone between 200 and 400ms.
The repeater once accessed, must radiate the same CTCSS tone at nominal
level of 10% of maximum. I.e. +/-500Hz for 25kHz units and +/-250Hz for
12.5kHz unit.

73 Ian G4FSU