Astro_Spectra
Member
You can easily figure if your wanted frequency is going to work by dividing it by 5 or 6.25 kHz. If the remainder is zero then it will work. Example:
154.3775 MHz is the same as 154377.5 kHz so dividing that by 5 giver 30875.5 so that's not going to work. You could tell before starting because writing the frequency in kilohertz immediate shows the 0.5 and an even 5 ain't going to fit that.
Let's try 6.25 kHz:
154377.5 kHz divided by 6.25 gives 24700.4 so that's not going to work either.
So the radio changed it to 154375 kHz which is divisible by 5 (and also by 6.25 kHz as it happens). But that's going to sound distorted on narrow FM and probably wont work on DMR.
Since the radio is intended for amateur use it may not have the right synthesizer design to deliver steps of 2.5 kHz. Some US frequencies, particularly at VHF, are a strange legacy of the old 120, 60, 30, and 15 kHz bandwidth channels that have been used over the history of FM operation. Most of the rest of the world used 50, 25, and now 12.5 kHz bandwidth channels and the needed step size is usually equal to half the channel size.
154.3775 MHz is the same as 154377.5 kHz so dividing that by 5 giver 30875.5 so that's not going to work. You could tell before starting because writing the frequency in kilohertz immediate shows the 0.5 and an even 5 ain't going to fit that.
Let's try 6.25 kHz:
154377.5 kHz divided by 6.25 gives 24700.4 so that's not going to work either.
So the radio changed it to 154375 kHz which is divisible by 5 (and also by 6.25 kHz as it happens). But that's going to sound distorted on narrow FM and probably wont work on DMR.
Since the radio is intended for amateur use it may not have the right synthesizer design to deliver steps of 2.5 kHz. Some US frequencies, particularly at VHF, are a strange legacy of the old 120, 60, 30, and 15 kHz bandwidth channels that have been used over the history of FM operation. Most of the rest of the world used 50, 25, and now 12.5 kHz bandwidth channels and the needed step size is usually equal to half the channel size.