Dick, I think you missed his point. If the scanner's microprocessor leaves you tuned several Khz off-channel, making the receiver more narrow would actually make the problem worse.
73, Paul, AE4KR ----- Original Message ----- From: ocwarren2000 To: [email protected] Sent: Monday, February 18, 2008 1:43 AM Subject: [Repeater-Builder] Re: Wide Band / Narrow Band --- In [email protected], "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: [email protected] > [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] > Sent: Sunday, February 17, 2008 12:09 PM > To: [email protected] > 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
