--- In Repeater-Builder@yahoogroups.com, "Jim Cicirello" <[EMAIL PROTECTED]>
wrote:
>
> We are going through the same growing pains here in Rural Western
New York.
> The problems with the NON-TRUNKING SCANNERS, is they will not go
out to 12.5
> KHz or even lower of a split. Here is an example; one of our
frequencies,
> 155.0475. Now if you try to put that in your BC-895XLT it will
round off.
> Another problem is that on the narrow band frequencies, they use a
deviation
> of about 3 KHz. The scanners, even the new TRUNKING SCANNERS that
will go
> out to the new narrow band frequencies will NOT consistently decode
the
> lower generated PL Tones below about 4 KHz. I called Uniden and
told them
> that I wanted a list of scanners that would do the new narrow band
> frequencies BUT DID NOT NEED TRUNKING. He told me that the only
scanners
> they have capable of narrow band are the TRUNKING UNITS. Now if you
are
> close to the transmitter, you can sometimes hear the rounded off
frequency
> OK without distortion. And if the PL don't decode, use carrier
squelch.
> Hopes this helps. Join the crowd of the new Narrow Band Generation.
>
>
>
> _____
>
> From: Repeater-Builder@yahoogroups.com
> [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED]
> Sent: Sunday, February 17, 2008 12:09 PM
> To: Repeater-Builder@yahoogroups.com
> Subject: [Repeater-Builder] Wide Band / Narrow Band
>
>
>
> Our local fire, police and ambulance departments are going to
Narrow Band
> per the FCC. I was told by one fire department that their pagers
will only
> work one narrow band. Now this guy must be talking about the tones
for the
> pagers? But to me wide or narrow the tones are the same. Right?
Going
> narrow just means that they are taking up less of the band width
for their
> frequency? He also said that scanners will not be able to listen to
them
> unless the scanner is set up for narrow band. His wife gave me her
nice
> Uniden BC-895XLT scanner because her husband told her the same
thing.
> Some one who is in the know would like to fill us in on the topic.
All EMS
> departments will be narrow band by April, in our area; from what he
said.
>
> Rod
>
Well, guys, it's not all that hard to narrow band a wide
band receiver, by narrowing the IF frequency amplifier / limiter
circuit string by decreasing the coupling between stages and making a
responce curve that looks like an inverted "V" rather than a modified
inverted "W"..!! Modifying the discriminator depends on what kind of
circuit it uses.
Years ago when everybody went down to + - 5kc from + - 25KC, that's
what we did.. On transmit just turn down the modulation.. best done
with a Deviation Meter or a Service Monitor..
Dick, CET, W7TIO
