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World Radio League

How to Make a Contact on Ham Radio The Easy Way (Using Simplex)

Simplex Contact Guide

While repeater operation is one of the more popular uses with a handheld amateur radio, there is another type of operation that you should be prepared for when you program your radio.

Simplex operation is … SIMPLE! It relies on using one frequency to talk to someone else, or everyone else, all on the same exact frequency. In simplex — or single-frequency — operation, you use the exact same radio frequency for transmitting and receiving.

 Diagram of Simplex Operation

If you are familiar with using FRS or Family Radio Service walkie-talkies and you are using Channel 7 for instance, everyone you are talking with is listening and transmitting on 462.7125 MHz. When one person transmits, everyone else on the same channel hears the same thing.

Simplex operation on amateur radio frequencies is structured in that certain frequencies in the VHF and UHF bands are set aside for simplex operation. In addition, certain frequencies are designated for calling purposes so you can reach out to other hams using simplex and either stay on the same simplex channel or switch off to a different simplex frequency so you don’t tie up designated national calling channels.


How and why you should use simplex frequencies 

Let’s take a look at how and why you operate on simplex.

Simplex frequencies on VHF and UHF ham bands can accommodate a number of uses. Here are some common, and even more intense, use of simplex ham frequencies:Amateur radio events: If you’re attending a hamfest, a large electronics flea market where you can buy and sell used ham equipment and other electronics, you might stay in touch with some of your radio friends on a simplex frequency you choose before the event, so you’re all on the same frequency when you arrive. That way you can shout out for bargains you know your friends are looking to find!

An electronics flea market, called a hamfest and typically sponsored by a local amateur radio club, attracts electronics vendors as well as hams selling their used equipment. You can keep in touch with your radio friends at a hamfest on a discreet simplex frequency.

Public service events: Some amateur radio organizations provide communications for various community events, augmenting event personnel through the use of their radios. If the event is a close-in event that only covers a few blocks at most, a simplex ham frequency may prove sufficient for such use to keep repeaters open for other communications, including emergencies.

Traveling/commuting: If you’re on a long trip, it might get bothersome to constantly reprogram your radio for repeaters along your way. Thus, many mobile hams like to monitor simplex frequencies to reach out to other mobile hams, especially during long travels and even during regular commutes. Some hams may put decals on their car windows to indicate what simplex frequency they are monitoring (146.520 MHz is typical) in case anyone else sees their antennas and call sign license plates while passing on the highway or street.

This is an example of a decal used to advertise what simplex frequency you are monitoring so other hams driving by can potentially call for you on the radio!

Out of repeater range: You may find that you live in an area without ham repeaters or you may find that there are no repeaters around you while traveling. Thus, you can always try to reach out to other hams on a discreet simplex frequency. Holler on a simplex frequency and see whether you can make a contact.

Contests: One amateur radio activity is to try and contact as many other hams as possible during a set time period, such as a weekend. During most contests that include the use of VHF and/or UHF frequencies, you can get contest score credits for making contacts on non-national simplex frequencies. For instance, while you would be prohibited from using the national simplex frequency of 146.520 MHz, you still could give a shout out for other stations operating in the contest on 146.550 or 146.580 MHz, two other popular 2-meter simplex frequencies.

Friends: Hey, there’s nothing to say you and some friends can’t use a designated simplex frequency for your own use on an every-day basis, as long as you don’t interfere with other users on the frequency. 

Nets: Some local nets may occur on simplex frequencies to ensure you have the capability to reach other hams. These nets allow amateurs to test their equipment on the air to ensure they can talk to others. Nets typically are run on a weekly or monthly basis with a net-control operator who acknowledges hams who check in on the air during the net. Don’t be shy! Listen first and then chime in. Here’s a video example of a net in operation on VHF: https://youtu.be/HbkXhWVWffE

We can’t possibly cover all the various activities that hams use simplex frequencies for, but you may find specialized operations in your area that you need to avoid or perhaps join in! Some of these users may include geocachers, search and rescue teams, families, railfans, plane spotters, emergency services teams, and much more! As you can see, amateur radio allows diverse operations on myriad frequencies. Tune around and shout out on simplex.


National simplex frequencies

Each VHF and UHF ham band has simplex frequencies that are set aside on a national basis. These are of note for Baofeng owners:

2 meters: 146.520 MHz

1.25 meters: 223.500 MHz (program this on your tri-band Baofeng)

70 centimeters: 446.000 MHz

When you call out on a national simplex frequency, it is best to switch to another simplex frequency (or even a repeater within range of both or all stations) to avoid tying up the frequency. National simplex frequencies are best used for “calling” purposes only. You call out to reach a specific station or any station that might hear you and when you establish contact, switch to another simplex frequency. However, if you live in a very rural area, you might get by staying on the national simplex frequencies if you don’t interfere with other stations that may need to use the frequency.


Other simplex frequencies

We talked about national simplex frequencies that most hams monitor on a routine basis. We also mentioned that you should switch to another simplex frequency after establishing contact on a national simplex frequency. So what are those other simplex frequencies?

Here’s where we say your mileage may vary. Band plans are established not only by the American Radio Relay League, but also state and regional frequency coordinating bodies. These organizations not only set guidelines as to how hams should use their VHF and UHF frequencies, but also approve and coordinate frequencies used by repeaters and links between repeaters. To find the VHF and UHF band plans for your local area, try using Google to find your state’s frequency coordination body, such as if you search for “Illinois repeater association’ for Illinois’ governing body, you’ll find the website for the Illinois Repeater Association. The organization includes a band plan page that tells you what frequencies you can use for simplex frequencies without causing interference to other operators in that state.

While band plans for your area may vary, here is a list of generally acceptable frequencies for routine simplex amateur communications for 2 meters, 1.25 meters, and 70 centimeters.

2 meters: 146.400, 146.415, 146.430, 146.445, 146.460, 146.475, 146.490, 146.505, 146.535, 146.550, 146.565, 146.580, 146.595, 147.405, 147.420, 147.435, 147.450, 147.465, 147.480, 147.495, 147.510, 147.525, 147.540, 147.555, 147.570 and 147.585 MHz.

FACTS: The most popular simplex frequencies are 146.550 and 146.580 MHz. Take note, however, that some of the frequencies in the above list may be used for repeaters in larger metro areas and you should avoid using them and causing interference to other operators. Before using ANY simplex frequency, be sure to monitor first!

1.25 meters: (use if you have a tri-band Baofeng handheld) 223.400, 223.420, 223.440, 223.460, 223.480, 223.500, 223.520, 223.540, 223.560, 223.580, 223.600, 223.620 and 223.640 MHz.

70 centimeters: 440.900, 440.925, 440.950, 440.975, 441.000, 441.025, 441.050, 441.075, 445.900, 445.925, 445.950, 445.975 and 446.025 MHz.

FACT: Some of the 441-MHz frequencies above may be used on a local basis for digital hotspots, so it is advised to avoid their use, especially if you hear noise on those channels.


What simplex frequencies should I program into my Baofeng? 

Here’s an easy list of simplex frequencies that every amateur radio operator should have programmed into their handheld or mobile radio to allow the flexibility of direct communications, especially for use when out of range of repeaters or for emergency communications purposes. If you can’t program in all usable simplex channels, be sure to program these channels at the very least.

2 meters: 146.520, 146.550 and 146.580 MHz.

1.25 meters: (use if you have a tri-band Baofeng handheld) 223.500, 223.520 and 223.540 MHz.

70 centimeters: 446.000 and 446.025 MHz.


Why can’t I use any frequency for simplex? 

Quite simply: You could cause interference. Amateurs should never intentionally interfere with other operators because we’re just that way. 

For instance, you might choose to use 145.800 MHz to talk with some friends. However, you will incur the wrath of other operators over a wide area who are monitoring that frequency to hear ham-astronauts aboard the orbiting International Space Station! Yeah, you don’t want to go there. 

Likewise, you could cause interference to amateur satellites, repeater links, packet stations (sending data from one station to another), amateur television stations, weak signal aficionados, and more. In addition, you could be using a frequency that is used as the input frequency for a repeater and your signal unknowingly could be retransmitted over a large region or metro area, or even perhaps half a state! That would prove highly embarrassing when you find out you were causing interference. 

Before using any simplex frequency, MONITOR the frequency to make sure you don’t interfere with operations or communications already in progress. Keep in mind that when listening on simplex frequencies that you may hear one station, but may not hear the other station because it is farther away from you than the other station on the frequency. Listen long enough to make sure there are NO stations using the frequency before transmitting.

Lastly, be sure you’re not causing interference to a frequency that could be in use by members of local Amateur Radio Emergency Service (ARES) or Radio Amateur Civil Emergency Service (RACES) organizations, search and rescue teams or even a local club that is conducting a fox hunt (practice exercise for members to track down a low-power hidden transmitter) or in support of a community event such as a marathon. LISTEN! LISTEN! LISTEN!


Should I use subaudible tones on simplex? 

Here is one last note on whether or not you should use subaudible tones while operating on simplex. Generally speaking, you should not use subaudible tones such as CTCSS (continuous tone-coded squelch system) or DCS (digital code squelch). It is only recommended that you use them for a specific purpose or you fully understand their use.

Subaudible tones allow you to use a frequency and not hear others on the channel. See where this could be a problem? You could be using CTCSS to communicate with another ham and you could be causing interference, and the other stations you are interfering with would not be able to tell you of the problem. However, using CTCSS or DCS could prove valuable for emergency services work on ham frequencies. 

If you understand the concept of CTCSS, then the only recommendation is to use 100.0 Hz as a subaudible tone on TRANSMIT ONLY. This way you still can hear other stations on the frequency, yet if there is someone else who is set up only to decode a 100.0 Hz tone, they will hear you. So again, if you don’t need it or don’t understand it right now, don’t use a tone on simplex frequencies. If you understand it, set up your simplex frequencies in your radio to receive in carrier squelch, or basically no tone, and transmit with a 100.0 Hz tone.

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