> What is the allowable deviation for a two meter digipeater in
> amateur service? Is 15 kHz excessive?
Lord, yes, 15 kHz is excessive. The occupied bandwidth would be on the
order of 35 kHz for Bell 202 tones. You'd be clobbering both adjacent
channels.
5 kHz is typically considered the maximum deviation for narrowband FM, and
often lower than that is necessary on 15 kHz-spaced channels on 2m.
There's no reason to run more than 4 kHz for AFSK. Tests I did back in the
day when AX.25 packet started to get popular showed that 3.5 to 4 kHz was
optimum as the best compromise between maximizing S/N and avoiding
distortion in receiver IF's, i.e. the most reliable decode on weak signals
was in that 3.5 to 4 kHz range for the radios I was testing with (typical
ham rigs of the day, Kenwood TM-221A and an Azden PCS-5000? was what I
remember experimenting with).
Set the deviation limiting at 4 kHz, and turn the audio down such that the
high tone (2200 Hz IIRC) is just slightly below the limiting point and you
should be good to go.
--- Jeff
