Simplex Operations

Simplex is as easy as two radios talking directly to each other. There are established frequencies but any frequency within the bands can be used. Simplex is mostly referring to vhf and uhf frequencies. HF is simplex by default since repeaters are not used at those frequencies.

Madison uses a default set of frequencies and participates in testing of those frequencies. This document is to cover those procedures and to provide standardization for the options on those frequencies and the choices for alternative frequencies and methods

Our stand frequencies for testing is 146.550 and the alternate 145.550.

  1. Tests start at the end of the normal net.

  2. The stations wishing to participate QSY to the 146.550.

  3. The net control operator goes through the roster covering Madison stations.

  4. Each station reports when called.

  5. If a station hears a response to the call they will report to the net control operator that they heard the call.

  6. Each station should maintain a log of stations that they heard during the role call.

  7. At the end of the role call , the net control operator will call out for any non Madison stations.

  8. Any station not hearing the net control station should contact a station that they can hear to be relayed into the net.

After the formal test stations are encouraged to engage in simplex calls to test their coverage. All contacts should be logged with a signal report in the X59* format and send there results to Results will be compiled and used to establish best practices for use of simplex and what stations can be considered as net control in an emergency.

Any station can start a net and assume net control in an emergency. Many times two or more stations will be needed to provide coverage.

X59 just eliminates the tone since tone is only valuable with CW.

Alternate Uses of Simplex.

Simplex covers analog and digital modes of communication. We will first cover our analog options and practices.

Analog Simplex

Program your radio with the following frequencies.




Label each as required to be able to know which frequency is used. An example is below but use what you would like. 1 and 2 after the digital listing is the Time Slot for testing. See below.

Extra uses for analog.

Adding a number of the same frequency can provide a option that may be useful after our testing. Add a PL tone to a analog channel listing. This can be a receive or send tone. It can allow the use of simplex to talk to groups set up with that tone. Other stations will not activate without the PL tone. This allows for communication to specific groups and provide information without the other group being disturbed.

This has been tested in SSB testing and functioned perfectly. One group goes to upper and one group goes to lower SSB. Overly, strong signals can compromise this operations by splatter.

Digital Simplex

Digital Simplex has a number of frequencies and can be set up in a number of ways. Below is a list of simplex frequencies. The important part of simplex in digital mode is to set the talk group to simplex – TG99. You can also set up the TS. By default Madison is using TS2 but if there is room you can add a channel using TG1, Since this is using the time slot method you should not hear the TG2 traffic. There are work arounds for this where both slots can be opened but that will depend on the model being used. Older versions of code used both time slots bit now most codes are restricted to a single time slot.

A CSV file is linked below. You should be able to add the data to your radio easier.

Simplex CSV