The Basic Settings for 2-way FRS / GMRS Radios

In this blog we will only discuss how to simply set the FRS / GMRS radios to communicate each others, we will not talk about other features and more deep settings.

What is FRS / GMRS ?

GMRS: General Mobile Radio Service. It is a service for short distance 2-way communication using FM UHF radio service.

FRS: Family Radio Service. It is a kind of personal radio service uses 462 and 467 MHz UHF band.

What is FRS / GMRS radios ?

Any radios with FRS / GMRS features :).  OK, let us limit what radio devices we are talking about: We will discuss the settings using the Unden GMR3740-3CK 2-way FRS/GMRS radios package:


Set the radios to communication each others:

After we purchase the radio package from store, we just want to let them work right away, we do not care about other features, the most important is how to make the 3 radios communication each others.


Check the picture above which is a front panel of the radio. For communication, we will have to set 2 important options:

1: The Channel

2: Sub Code

If each radio set to same channel and same sub code, then you can use them to talk. On the image shown above, the number 12 is Channel 12, the 83 is the sub code.

How to set Channel

There is a Channel button on each radio device, you can click the small triangle up or down to adjust channel. But we have to know you might not set any channel which you want since some channels need license.

We can totally have 22 channels to select;

Channel 1 ~ 7 and Channel 12 ~ 22 have the range up to 30 miles, which are GMRS channels. If you set in those channels, it indicates radio device will scan GMRS channels, but you have to know that you need GMRS license if you want to use the GMRS services and frequencies. So if you only want a home usage, please avoid setting to channel 1~7 and 12 ~ 22;

For home usage and short distance usage, we can select channels 8 ~ 14 which have the range of up to 5 miles (FRS). it is enough to us.

If you set a GMRS channel, you will see hi icon displayed, if you set a FRS channel, you will see lo icon. In above image, we can see we set a FRS channel.

How to set Sub Code

Each channel has 122 sub codes. we can set any one of them, but OFF code is the one of 122, we do not recommended set to OFF since more security requests even you can still receive signal;

1:When you open the radio device, click the Menu button, make sure you see the sub code indicator flashing now, if you do not see the indicator flashing, click Menu button one more time;

2: Use Channel button up or down to set a sub code which you want;

3: Press menu button to exit the sub code setting;

4: Press any other key but not Channel and Volume buttons. to let the radio returns to idle status.

How to talk

On each of radio device and on the left side, there is a side button called PTT button. hold the up section of PTT button, you can speak but other radio devices can only listen, after you finished your talk, release the PTT button so that other people can start speaking.

Make sure you see a tx icon when you start to speak, otherwise other people can not hear you.