[OZAPRS] APRS receiver setting

Ray Wells vk2tv at exemail.com.au
Fri Nov 27 15:32:02 EST 2009


I'd personally consider 3khz too low in a nominally 5khz system. 
However, (there's always a "but") given that the TNC/O.T. doesn't wander 
away from the microphone like some mouths do, you'll always have that 
level once set up, and some receivers with poor IF shape characteristics 
can object to higher deviation (but still below 5khz) on low input 
signals and can distort terribly. The venerable FM828 is particularly 
good in this regard and will accept more than 5khz and stay clean.. The 
FM92 series is good as well if you take de-emphasised audio. The couple 
I tried for discriminator audio had terrible distortion at even 3.0khz 
and, yes, they had a 15khz IF.

That article Darryl referenced is an excellent article that I've been 
recommending for years.

Ray vk2tv

Scott Evans wrote:
> I've always used the setting of 3KHz (on VHF) as some Philips PRM 
> series clips anything above 3.5/5KHz but the your mileage may vary! 
> but if you have the means to measure what is happening around you then 
> maybe match that.
>
> -- 
> Scott Evans <scott at vk7hse.hobby-site.org 
> <mailto:scott at vk7hse.hobby-site.org>>
>
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