Narrow band technical question
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firedog359
- Posts: 53
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- What radios do you own?: MA/COM KMC-300,ICOM F50V
Narrow band technical question
Hello all, First off I'm not a radio technician. I'm just a Firefighter who loves to collect older/ vintage radios and dispatch consoles so I really know very little about the technical aspects of a radio. Every piece that I have works. I don't like things that just look nice. I want them to work just as well as the day they came from the factory. Pretty much everything that I have is wideband and can't be transmitted on and that irks me to no end. I really would like to learn what parts in the radio make it wide or narrowband and why you just can't change out those parts and make it narrow band. Can someone help me understand this?
Re: Narrow band technical question
Well, a start would be listing the equipment that you have that you want it to be "narrow".
Schrodinger's Radio: It is simultaneously too loud and too quiet, but you will never know which until someone transmits.
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RadioSouth
- Batboard $upporter
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- Joined: Mon Sep 03, 2001 4:00 pm
Re: Narrow band technical question
The other issue is although you can technically tweak some radios down to 12.5 spacing (Motorola even made kits for this purpose for some radios) they're not going to be FCC compliant on 12.5 (they would need to be re-tested which isn't really practical). I understand your attachment to classic Motorola equipment but unless they're going to be used for Ham or is a Marine radio their day has come. Some of mine are being used as receive radios but the rssults of the tighter audio width vary greatly (some are hardly noticeable, others with tighter filters don't sound right).
Last edited by RadioSouth on Fri Sep 04, 2015 5:37 am, edited 1 time in total.
Re: Narrow band technical question
If they worked before, they still do now. The physics of radio didn't change. Just the occupied bandwidth. You'll still hear calls on all those radios whatever they are, and you could still transmit on them if (A) you speak softly, and (B) you're licensed (but we won't dwell on that part). From a strictly hobbyist and preservationist POV, all of your equipment still functions. Being able to legally operate is entirely a different matter, and one you may not be able to resolve at all for some of them.
Re: Narrow band technical question
Hello:
The FCC as your aware did go from wide band to narrow band.
Just in case that doesn't make sense as to what a nb is versus a wb then think of it as this for example.
Lets just for an example 25 kHz wide band is transmitted at 25 inches wide through the air and that a 12.5 kHz narrow band radio transmits only 12.5 inches wide through the air on its tx signal.
Ok if you look at the two now youll notice that a narrow band 12.5 radio only transmits at half the signal width creating yet another 12.5 nb channel for use.
Yes Motorola did make 25kz wide band to 12.5 kHz narrow band kits to change certain radios to narrow band. (Example GP300 and GM300 mobiles)
HOWEVER THEY WERE NOT APROVED BY THE FCC AS I UNDERSTAND !
Reasons I had heard and I said HEARD was that the radio shops were not certified or qarranteed to actualy convert a 25 wide to a 12.5 nb thus leaving the possibility of a improper conversion that wouldn't meet fcc specs .
Now that's entirely possible and yes many radio shops are capable of converting but fcc has a stand that its better that a radio manufacturer make the radio as nb and thus better qarantees a proper working nb radio.
Now that just what I have been told and heard so cant prove or disprove the gossip.
Also a 25 kHz wide band radio normaly transmits a 5kz audio level where the 12.5 kHz narrow band transmits at 2.5 kHz audio levl.
What this means is that a wide band radio transmits louder than a narrow band is that the audio from a louder wide band radio will be twice as loud as a narrow band radio talking to another narrow band.
Also true is a narrow band radio talking to a wide band radio will sound half the normal audio as its audio is half and will sound soft .
But youll still have full audio speaker output on a narrow band to narrow band due to the receiver in each radio amplifies the signal twice that received to make it sound just as loud as a wide band did but only in the receiver of the radio not out in the air transmitted to keep hings from creating disturbances to aboe and below channels now that they are 12.5 kHz apart rather than 25khz separation.
OK NOW I PUT THIS EXPLANATION IN AS DOWN TO EARTH TALK SO ALL COULD UNDERSTAND AND I KNOW THE REST OF US SAVVY TECHS CAN EXPAND ON THIS.
So don't take it as the whole truth but as a get you an explanation so the commoner can start to understand it as well.
And we were all commoners at one time.
Motorola did have some radios that could be flashed or reprogrammed to 12.5 narrow band that would be fcc nb compliant but we would need the radio model number to inform you if by chance yours was one of them.
Satelite
The FCC as your aware did go from wide band to narrow band.
Just in case that doesn't make sense as to what a nb is versus a wb then think of it as this for example.
Lets just for an example 25 kHz wide band is transmitted at 25 inches wide through the air and that a 12.5 kHz narrow band radio transmits only 12.5 inches wide through the air on its tx signal.
Ok if you look at the two now youll notice that a narrow band 12.5 radio only transmits at half the signal width creating yet another 12.5 nb channel for use.
Yes Motorola did make 25kz wide band to 12.5 kHz narrow band kits to change certain radios to narrow band. (Example GP300 and GM300 mobiles)
HOWEVER THEY WERE NOT APROVED BY THE FCC AS I UNDERSTAND !
Reasons I had heard and I said HEARD was that the radio shops were not certified or qarranteed to actualy convert a 25 wide to a 12.5 nb thus leaving the possibility of a improper conversion that wouldn't meet fcc specs .
Now that's entirely possible and yes many radio shops are capable of converting but fcc has a stand that its better that a radio manufacturer make the radio as nb and thus better qarantees a proper working nb radio.
Now that just what I have been told and heard so cant prove or disprove the gossip.
Also a 25 kHz wide band radio normaly transmits a 5kz audio level where the 12.5 kHz narrow band transmits at 2.5 kHz audio levl.
What this means is that a wide band radio transmits louder than a narrow band is that the audio from a louder wide band radio will be twice as loud as a narrow band radio talking to another narrow band.
Also true is a narrow band radio talking to a wide band radio will sound half the normal audio as its audio is half and will sound soft .
But youll still have full audio speaker output on a narrow band to narrow band due to the receiver in each radio amplifies the signal twice that received to make it sound just as loud as a wide band did but only in the receiver of the radio not out in the air transmitted to keep hings from creating disturbances to aboe and below channels now that they are 12.5 kHz apart rather than 25khz separation.
OK NOW I PUT THIS EXPLANATION IN AS DOWN TO EARTH TALK SO ALL COULD UNDERSTAND AND I KNOW THE REST OF US SAVVY TECHS CAN EXPAND ON THIS.
So don't take it as the whole truth but as a get you an explanation so the commoner can start to understand it as well.
And we were all commoners at one time.
Motorola did have some radios that could be flashed or reprogrammed to 12.5 narrow band that would be fcc nb compliant but we would need the radio model number to inform you if by chance yours was one of them.
Satelite