Narrow/Wide Band...It's all relative

Modified on Sat, 25 Feb 2023 at 02:07 PM

Narrow/Wide's all relative
There are two parts to this... frequencies and modulation.


The new commercial frequencies and those assigned to Mars/Caps operations are often on 2.5 kHz steps. i.e., 147.2125, 154.6735, etc. While many radios can do these frequencies, most amateur radio  radios cannot.

Basically, amateur radios can do these frequencies to the fourth decimal (where the x can be replaced with any number)
  • xxx.x125
  • xxx.x375
  • xxx.x625
  • xxx.x875


That's it!! You cannot dial others in from the face of the radio even with the step set to 12.5 kHz. The internal components of the radio just cannot generate other frequencies to the fourth decimal. So, while in the example the radio would be able to do 147.2125, it would not be able to do 154.6735 (the closest it could get would be 154.6625 and while it might hear the signal, it could never transmit well enough to be used on that channel.)

Newer radios can do 6.25 khz steps giving them the ability to tune more frequencies. There will still be those that they cannot access (i.e., 154.6735 in this example - the closest is 154.66875 then the radio steps to 154.675.)

These newer radios can do:


While this gets you more frequencies and even tuning to the 5th decimal point, lots are missing. If you cannot tune to the frequency from the face of the radio, the program cannot put the frequency into the radio. But wait, you say another program will let you enter those strange frequencies... well good luck with how well that will work on the radio.

Radios that do 2.5 kHz or .5 kHz frequency steps can tune to the "new" - frequencies. As of today 01/16/2012 the Kenwood TH-F6 and TH-K20 and the Wouxun KG-UV6D are known to have these step sizes available... not to say there are not others. These radio will be able to do the narrow frequencies such as 154.6735.


When you transmit the signal modulates above and below the frequency by 2.5 (narrow) or 5 (wide) hertz. This is just how radio waves work. On most radio, narrow modulation is set up for a memory channel with though a check box for "Narrow" or as FMN (FM Narrow) as the operating mode.

If the radio has this option, it will be in the programmer in one of these two ways.


The most important part of listening is being able to tune the frequency. As far as listening on Wide or Narrow FM
  • Narrow Channel heard on FM receive - audio will be low. (think of it this way, there is not as much signal there as the radio is accustomed to hearing).
  • Narrow Channel heard on Narrow FM receive - will sound like any other channel.
  • Wide FM being heard on Narrow FM receive - Audio will be distorted (there is too much signal for the receive mode the rest becomes distorted)
  • Wide FM (regular repeater signal) heard on FM receive - Audio will be normal.

Ultimately, if your radio can tune to the frequency, you will be able to hear it. 08/07/2013 01:33PM

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