Ron Milione, Ph.D. CETma W2TAP

 A repeater is a device that performs 3 basic functions:  It receives and demodulates an RF signal.  It regenerates the audio information.  It modulates and retransmits the audio on a new RF carrier.

 Amateurs experimenting with VHF/UHF in the 1930’s discovered that propagation was generally limited to line-of-sight.  The limited working range offset the advantages of VHF gear for mobile/portable operation (small antennas and light equipment)  In the 1950’s, widespread availability of WWII surplus electronics led to the creation of the first repeaters on the West Coast.  The repeaters were AM and used frequencies on the 2 meter band.  By the 1970’s, standard offsets and FM were introduced.

 Repeater antennas are almost always vertically polarized and have an omnidirectional azimuth pattern.  Generally the same antenna is used for transmitting and receiving.  The antenna is mounted as high as possible in order to have good line-of-sight coverage.

 A duplexer is a special type of filter that allows a single antenna to transmit and receive simultaneously on two closely spaced frequencies.  A typical duplexer consists of two pairs of resonant cavities.  Two pass the transmit signal from the transmitter to the antenna while rejecting the received power.  The other two pass the receive signal from the antenna to the receiver while rejecting transmitted power.  Typical rejection is better than 70 dB, while attenuating the desired signal less than 2 dB

 A repeater receiver must have good sensitivity and excellent selectivity, in order to have adequate rejection of the transmitted signal.  The receiver will have at least two outputs:  Audio output  Carrier detect  The audio output can contain both audio signals and out-of-band control tones.  A signal appears on the carrier detect line when an RF carrier breaks the receiver’s squelch. (a repeater use requests service)

 The carrier operated relay turns on the transmitter in response to:  a carrier detect signal  an ID transmit signal

 The transmitter should meet the following criteria:  High spectral purity (to avoid unnecessary receiver interference)  Highest possible output power (for greatest coverage)

 The ID timer performs basic ID housekeeping tasks:  Generating appropriate ID’s  Tracking time between ID transmissions

 The control operator (repeater trustee or his designee) needs to be able to control the operation of the repeater transmitter, in the event of:  Electrical malfunction  Inappropriate use of the repeater  To implement the external control function as well as some other desirable features, the carrier operated relay is generally replaced by a repeater controller

 A repeater controller provides (at least) the following capabilities  Telephone line interface  Voice ID and announcement capability  Linking  Transmitter controls  Special supervisory tones (courtesy beep, etc.)  DTMF decoding  CTCSS decoding

 Via telephone  The repeater operation is controlled through DTMF tone groups sent through a phone line.  Via RF link  The repeater controller is accessed via a separate simplex RF link (above MHz)  On-the-Air  DTMF tones sent into the repeater are used to control its operation.

 An autopatch is a connection between an amateur repeater and the PSTN that permits a repeater user to make a phone call from his/her radio, provided that the radio has DTMF capability.  The call made through the autopatch is subject to all the restrictions of an amateur transmission.  The popularity and utility of of autopatch has declined significantly with the advent of cell phones.

 A reverse autopatch is a connection from the PSTN to an amateur station through a repeater.  The call is originated by the PSTN subscriber, not the mobile amateur.  The originator of the call should be an amateur – the call will be carried on amateur frequencies  Once again, the restrictions on amateur transmissions apply to these communications.

 All modern repeater controllers have an autopatch capability. All that is required is a connection between the phone line and the controller.  Cell phones may also be used to provide a line for autopatch. If the line will also be used to control the repeater, an older AMPS cell phone is necessary.

 CTCSS is the “continuous tone coded squelch system”  A repeater using CTCSS will cannot be accessed unless a user transmits a subaudible tone with his audio information.

 Repeaters may be linked to increase the coverage available to the users.  Linking methods:  Internet – ilink, etc.  Telephone line  VHF/UHF link between repeaters (remote base linking)

 This type of linking uses VoIP (Voice over Internet Protocol) to connect repeaters via the Internet.  The repeater is connected to the Internet via a PC running software such as Ilink, Echolink, IRLP/Speak Freely  The software provides A/D conversion and compression for the audio and transceiver control.  The repeater may be accessed from the Internet by users who have VoIP capability

 Uses a dial-up link to connect two repeaters.  Primary repeater’s controller makes an autopatch call to the secondary repeater.  The secondary repeater’s controller answers the call and goes into reverse autopatch mode.  This type of linking is full duplex

 A separate RF link is installed between the primary and secondary repeaters.  FCC rules require that this link operate above MHz  When the primary repeater is opened, its controller routes audio to the RF link transceiver and puts it into transmit mode.  When the secondary repeater’s RF link transceiver receives a signal, this signal is sent to its controller, which retransmits the signal over the secondary repeater.  This type of linking is half-duplex (simplex)

 All transmission over a repeater should be in accordance with FCC Rules.  Amateurs have no “right” to operate on a repeater. The repeater or his/her designee grants operating privileges to amateurs.  Wait for the courtesy tone!!!!  The repeater should not be tied up by long conversations – use a simplex frequency for a long QSO.

MacroCommand / MessageMacroCommand / Message * Patch Autodial410Morning Net #Patch Down411Evening Net 026Time (male voice)420Skywarn Net 027Time (female voice)425Meeting Week 029Date426Meeting Tonight 400Repeater Off427Breakfast 401Repeater On430Outside Temperature 406Patch Disable431Rack Temperature

 FM Repeater operation is often the first type a new amateur attempts, and is the main mode for many amateurs  All repeater users should be polite, courteous and helpful to newcomers/visitors  The W2VL repeater is flagship repeater of LIMARC  W2VL  W2KPQ  W2KPQ  PL for all is 136.5