![]() On the 440 (70cm) band it is usually 5mHz positive or negative in relation to the transmit frequency. It simply takes the weaker received frequency from say a mobile or ht and re-transmits it (repeats) at a higher power level on a different frequency. On the 2 meter band, this separation between transmit and receive frequency is usually 600kHz either positive or negative in relation to the transmit frequency. The exciter modulates the audio coming from the receiver which is tuned to the transmitting stations’s frequency at the proper transmit frequency, and the power amplifier simply boosts its level so the signal will travel further. Most “machines”, as repeaters are sometimes called, have a transmitter composed of an exciter and a power amplifier. It’s also where CTCSS (Continuous Tone Coded Squelch System) or “PL” decoding takes place. It is set to receive the input frequency. This receiver is generally a very sensitive and selective one which helps weaker stations to be heard better by the repeater. It helps to reject very strong nearby frequencies from other repeaters or rf producers from getting into the repeater system. A duplexer has the shape of large tall cans and is designed to pass a very narrow range of frequencies and to reject others. It prevents the receiver and transmitter from hearing one another by the isolation it provides. The duplexer separates and isolates the incoming signal from the outgoing and vice versa. This device serves a major role in a repeater. The signal loss with hard line versus regular coax is much lower than in standard coax, so more power gets to the antenna and weaker signals can be received due to the very low loss of the “hard line”. Look just above the telephone lines and you will see much larger “aluminum” cable. It is very similar to cable tv line that you see strung between power poles around town. A type of specialized feed line called “hard line” is usually used. The feed line used on most repeaters is not just a piece of standard 50 ohm coax cable. Lots of repeater system antennas are located on a high hill or mountain.Īntenna systems for repeater use are usually very costly and have an omni-directional pattern. It usually is a high performance, high gain, heavy duty, and very efficient antenna located as high on a tower or structure as we can get it above the surrounding terrain. ![]() The antenna is used on transmit and receive signals that are going into and out of the repeater. Part 3 – Getting started on 2M FM (Basic Programming of a 2 Meter HT) Part 2 – Getting started on 2M FM (Basic operation of a 2 meter HT) Part 1 – Getting started on 2M FM (Repeater Basics) More about Repeaters. See these very informative videos below from K7AGE, Randy.Ī video is worth a thousand words! 3 Parts and a must see! (About 10 to 11 minutes each) Here’s a simple block diagram of a repeater below: A repeater “gets out” your signal and receives the station you are talking to with a far greater range and coverage area! You take advantage of the repeater’s higher elevation to increase your effective transmitting and receiving coverage versus your mobile or hand held transceiver! ![]() Repeater systems are used to “transfer” your transmitted and received signals to much higher levels electronically using large, very efficient high gain antennas, low loss feedlines and a transmitter and receiver that is rated for heavy or continuous duty. Why it’s needed: Your mobile or hand held transceiver, has a limited range due to it’s antenna height with respect to the radio horizon and rf attenuating surroundings. It’s nothing more than a “dumb electronic machine” with some smart people behind it. What: It’s a two-way radio system that receives on one frequency, then re-transmits what it receives on another frequency at exactly the same time. What is a Repeater and Why is it Needed, and How Does It Work? It contains a basic description of a ham radio repeater, how to use it properly and is written with the NEW HAM in mind for one of the most popular ham bands….2 meters. This article will help the New Ham to be more at home on repeaters and understand the operation and procedures on Ham Radio Repeaters. How to Use Amateur (Ham Radio) Repeaters by N4UJW
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