Calling any station in Klang Valley Area to perform an audio test on simplex repeater operated at V17 Channel 145.2125Mhz.

Please DO NOT get confused when you heard your own audio re-transmitting after finished conversation. This is how simplex repeater functioning.

If you heard CWID - 'CQ RPT', it means the simplex repeater is in operating mode.

Operating Guidelines as below (Please READ)

The operation of a simplex repeater is not specifically spelled out in the Guidelines and Rules and Regulations. This tends to create opportunities for argument regarding their operation. This document is intended to offer friendly guidelines in the setup and operation of simplex repeaters. Comments and suggestions are welcomed.

What is a "simplex repeater ?"A "simplex repeater" is used to extend the range of low power rigs such as handhelds by storing the signal transmitted on a frequency and then retransmitting it through a more powerful or better-situated transmitter on the same frequency. According to the rules, however, such a simplex repeater is not a repeater since it does not simultaneously retransmit the signals of another station and it does not retransmit the signals on a different channel or channels, as specified in the definition of a repeater. If a control operator is present and controlling the device, locally or by remote control, then it can be used.
There are two distinct classes of simplex repeater operation:

1. Normal Operations
2. Emergency Operations

Normal Operations

Normal operation of a simplex repeater needs to be "other ham friendly". Since many other simplex users will probably feel as though your simplex repeater is an intruder, friendly "co-operation" is necessary. A few concerns must be realized in order for your simplex repeater to be a good co-channel user.

First, avoid the use of common simplex frequencies, like 145.500 MHz, the Calling Channel Simplex Frequency. Many folks enjoy using straight simplex and unless you have a compelling reason, avoid using this simplex calling frequency.Above 2 meters you should endeavor to avoid repeater link frequencies as well. These frequencies can vary from region to region so it would be best to contact your local repeater coordinator to see if that particular frequency is being used.

Second, use a CTCSS (PL) tone to enable the receiver. This allows other users to use the simplex frequency without keying up your simplex repeater. If someone wishes to use the simplex repeater, then they must enable the proper CTCSS tone on their transmitter. If your simplex repeater also encodes the CTCSS tone (which is usually the case in most transceivers if decode is enabled) then it allows for selective monitoring of the frequency by those only wishing to hear users of the simplex repeater.

Third, ID the repeater and identify the CTCSS tone so that someone can communicate with you if you are interfering with their communications. Since another user probably won't want to try all the CTCSS tones to tell you that your are interfering with them, be friendly and announce it over the air. IDing can be a user simply saying, “This is 9W2XXX operating simplex repeater at 145.2125 MHz".

And finally, use the minimum amount of output power necessary to maintain communications. While this is common sense and conforms to rules and regulations, it is sometimes overlooked as a way to maintain good co-channel relations.Remember, some users think that simplex repeaters have no place on simplex frequencies. At least be courteous to other users if you intend to use one.

Emergency Operations

Simplex repeaters and emergency operations seem to be a natural pair. Since a simplex repeater can be set up nearly anywhere, including someone's car on a hilltop, they can be rapidly deployed wherever they are needed in a short period of time.

The first thing to remember about emergency operations is that communicating the message is the key. If a simplex repeater becomes an unwieldy due to its rather unnatural "store and forward" method, don't use it. But, if users have had practice drills using a simplex repeater (highly recommended!) then it becomes a more effective communications method.

Unless the simplex repeater is well known, it may be a good idea to remove any CTCSS tone. This will enable a user who may not be a regular user of the simplex repeater to access it during the emergency. If CTCSS is desired or necessary, then frequent announcements of the tone should be made.

If the needs for prominent communications are a concern, then setting up a simplex repeater on a popular simplex frequency may be necessary. If most of the local duplex repeaters have been knocked off the air, it may be desirable to set up the simplex repeater on the repeater's input/ output pair. This will somewhat mimic the disabled repeater's operation enough for communications to get through if the simplex repeater's receiver is listening to the duplexed repeater's input and transmitting on its output.


Keep your conversations short and simple. No matter how simplex repeater is used, encourage other hams to use it. This will create a body of users that, in an emergency, will be simplex repeater savvy. Encourage local ARES, RACES, or emergency management group to run occasional tests and drills on simplex repeater. Emergency use will help to justify simplex repeater’s existence during the normal times and foster an atmosphere of mutual respect from other hams.


Frequently Asked Questions (FAQs)

What is a simplex repeater?
A simplex repeater consists of a radio on a simplex frequency and a homebrew digital voice recorder. When a signal is received, the recorder stores the message (usually up to 60 seconds worth max.). When the received signal ends, the digital voice recorder retransmits the message on the same frequency. A commonly used term to describe this activity is "store and forward" which is what a packet radio digipeater does.

What's the difference between a duplex repeater and a simplex repeater?
A duplex repeater receives a transmission on one frequency and simultaneously retransmits it on another. The result is that the re-transmission is heard at the same time that the original transmission was made.

A simplex repeater stores the transmission and waits until it has finished before retransmitting it on the same frequency.

What are simplex repeaters used for?
Simplex repeaters are ideal for emergency or temporary situations where you need to communicate farther than a handheld radio would be able. Simplex repeaters can be installed in vehicles and parked on a hilltop to increase the transmission range.

Simplex repeaters are also handy for radio checks. When you send a signal to a simplex repeater you'll hear exactly what you sound like retransmitted back to you.

Who makes simplex repeaters?
Credit to 9W2LL and to everyone who contributes until to this operation stage.

How do you set up a simplex repeater?
Some simplex repeaters simply attach to the external speaker jack and the microphone jack of the radio. When a signal is received via the speaker jack, the unit records the transmission and then retransmits it thru the microphone jack on the radio. This is known as VOX (voice activated).Others will use the transceiver's COS and PTT lines.

I have further questions. Who can I ask?
Since many radio operators are not familiar with simplex repeaters, you may forward your questions to us via email:

Email :

Simplex repeaters can also share many problems that are also associated with duplexed repeaters. One excellent source of information is the Repeater Builders Technical Information Page.

Source : Rob, N1NTE, ADS-SR1, ARRL
Edited : WilayahV17 Simpeater Team – May 2009
Template by: WilayahV17