The 'correct' maximum depends mostly on your neighbors when it comes to
the ham band, but you should never run so much as to interfere with
adjacent channels. If you are operating in a 15 kHz bandplan where the
next adjacent channel above and below you is 15 kHz away, you should run
not more than 4.5 kHz deviation (resulting in a 15 kHz bandwidth). That
leaves no room for frequency error, but if you're on frequency, and your
neighbors are, too, it will help minimize any problems.
If you're in a 20 kHz spacing area, 6 kHz may work OK. You would have a
bandwidth of 18 kHz. That would allow for up to 0.5 kHz of frequency
error on both your part and that of your neighbors. Running 5 kHz
deviation would give you both 1 kHz to play with for frequency error
since your bandwidth would be only 16 kHz.
If you're running UHF in Ohio, give it up - you only have 12.5 kHz to
deal with. That means a technical maximum of 3.25 kHz deviation (12.5
kHz bandwidth). You may as well convert to SNFM (2.5 kHz deviation).
That said, some receivers, particularly scanners, are now designed with
much more narrow filters in them that will cut off at 17 kHz. That means
listening to your system on one of those will sound choppy on voice
peaks if you're running at 6 kHz deviation, or an 18 kHz bandwidth. So,
sticking with 5 kHz is the best bet. It will retain compatibility with
commercial specs (who are limited by law to 5 kHz maximum deviation for
NBFM).
Joe M.
mbloom0947 wrote:
>
> Dear John,
>
> Thank you for the helpful feedback. I can be a bit pig-headed at
> times. I really wasn't sure exactly what deviation to set. I did
> monitor other repeaters and they are as wide as I mentioned. Having
> said that, I will adjust the deviation back to 5 KHz max if that is
> best practice.
>
> Michael Bloom, W7RAT
>
>
> Yahoo! Groups Links
>
>
>
>
>
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