Amateur Repeater Linking

Back to Home Repeater Linking
By Kevin K. Custer W3KKC
With a few comments from Mike Morris WA6ILQ

The 'best way' to link repeater sites is really dependent on the situation and personal preference, so instead of giving you one "best" way, I'll give you a few examples of how it can be done and you can decide what it the best for your situation. This article is oriented towards linking repeaters in the amateur service, but the procedures could be followed to link commercial sites as well; assuming you are within the rules of the particular commercial service.

The "Remote Base" type link system is the most common because of its simplicity and low cost. Basically a second radio (even a old hand held or mobile rig) is connected to a repeater that you want linked to another and uses that new radio just as if it was a regular "user radio" on the other system. This "link" radio need not be duplex because of the way the link and repeaters are configured. Naturally the remote base radio will need to be on the same band, frequency, split, and PL as the repeater you are linking to. Remote Base operations in the amateur radio service can be carried out on any amateur voice band, even HF! Links below 220 MHz should be used on a part time basis because the FCC says that 'linking' must be done above 222.15 MHz, however Remote Base operation is left to individual and local interpretation.

Commonly, when deploying a link SYSTEM that will be * ON * full time - a repeater on 222.15 MHz. or above in the center of the desired coverage area is designated to be the system "HUB". Sometimes a new repeater is installed just to be the hub system. You can remote base, or "link", as many "outboard" repeaters into the hub as you wish, providing each of the outlying repeater site(s) has a good RF path to the hub. Unless you use an audio notch filter the MCW ID from the hub system will be heard through the entire system. If you like voice ID's, they need only exist on the hub. Since you can disconnect or "un-link" any repeater from the system, all outboard repeaters should have their own controller with it's own ID. The controller at the outlying sites needs to have 2 ports, one for the repeater and one for the remote base radio.

Several controller companies make controllers that have remote base link capability as part of their feature set. The sequence listed below is NOT an indication of preference. All have web pages at this repeater site.

ACC
Arcom
ICS
Link Communications - the RLC models
Micro Computer Concepts
NHRC - their models 4, 5, 6 and 10
Pacific Research Solutions
SCom - the 6K could be pushed, the 7K and 7330 are preferred (the 7330 is in current production)

How a Remote Base works.....
Basically, a Remote Base link is an addition to a normal repeater, which works like this: the user transmits on the input frequency, the controller recognizes the user and keys the repeater transmitter. Audio from the repeater receiver is transferred into the repeater transmitter, and the user is heard on the repeaters output frequency. When the user unkeys, the controller adds some 'hang time' (also called "carrier delay") on the repeater transmitter; during this time is when the courtesy tone, if any, is heard and the repeater transmitter drops after this time (usually 1 to 5 seconds) has expired. A repeater with a remote base operates the same as any other repeater, except that it has three modes: "remote base off" (i.e. repeater is normal), "remote base receive" (or monitor), and "remote base transmit" (or transcieve). In the receive or monitor mode the repater listens to two frequencies, the normal input and also whatever frequency the remote base radio is listening to. In most cases the courtesy beep is changed so that the listening user can tell that the system is in monitor mode, and which receiver the signal is coming in on (i.e. maybe "beep" for the main channel, and "boop" for the remote base channel). When the remote base is in transmit mode the user keys into the repeater on the input frequency, the controller recognizes the user and keys the repeater transmitter and the remote base radios transmitter, the user speaks and their voice gowes out not only on the repeater, but also on the remote base transmitter. Naturally, if the remote base is dialed on a repeater frequency, the users voice is heard on the linked repeater also. When the user unkeys, the remote base transmitter drops immediately while the repeater transmitter continues to transmit during the carrier delay ('hang time') as usual. The instant the remote base radio unkeys it reverts to receive mode and the remote base user will hear the far end repeater's courtesy beep (if any). The remote base could just as well be on a simplex frequency, or even an HF frequency (yes, you can run a 20 meter SSB killowatt using your 440mhz handheld). It is good practice to have the courtesy beep on the repeater side of the remote base to have an indication that the remote is in transmit mode - maybe a "beep" for the main channel receive, "boop" for the remote base channel receive, and "bee-boop" for remote base transmit enabled.

With this type of link, the remote base transmitter is only 'on the air' when the user is transmitting; thus the link transmitter follows the activity of the local user, (I.E. link PTT only during COS/PL). Activity heard on the remote base receiver makes the controller key the repeater transmitter and this audio is heard over the local repeater transmitter. So, immediately after the user unkeys the audio from the linked repeater is transmitted over the local repeater and you hear its courtesy tone and hang time. Since the remote base transmitter is keyed off and on, its duty cycle is really no more than the user so you don't have to be overly concerned about it burning up because of not being rated for continuous duty (unless someone on the repeater side sits on their microphone...).

Many times a handheld radio (like an Icom IC-2AT or IC-3AT) on low power is plenty good enough to link to another repeater. Remember you are linking one repeater site to another and many times this path is "line of sight". Remote base antennas can range from a simple rubber duck when linking to another local repeater to a tower mounted beam or corner reflector for more distant sites. Remember the FCC says linking antennas need to be directional. Some link systems are frequency and band agile, meaning you can select a particular band, frequency, split, PL frequency and even power remotely. The ACC controller company made this type of linking popular with the FC-1 and FC-900 link interfaces. A more modern combination is a NHRC-10 and an Icom 706 which covers 160m through 6m (complete with an autopatch), later models added 2m and 450mhz. Back in the 1970s the Arizona division of the Cactus radio group had a 12 channel 250 watt 2m remote base connected to one of the UHF system sites, complete with a remotely controllable antenna rotator - the Cactus Remote Antenna Pointing system. All TTL logic, no microprocessors, all crystal controlled.

Hopefully by now you see that this type of link system is just like operating a handheld or mobile rig that talks to another repeater while you sitting at your own repeater site. The only difference is you have the ability to do it while away from the site; in fact anywhere the repeater side of your remote base has coverage... From your office, home, the restaurant, anywhere.

Another trick: you can have a repeater at a hilltop site, with a 420mhz link back to your house, and operate your HF station at your house as a remote base. It would take a two-port controller at the repeater site feeding the link radio, and a controller capable of operating the HF radio at you house controlled by the link radio. WA6ILQ once watched a gentleman work Pitcarin Island on 20 meters using his 2m handheld while sitting in a booth at a Dennys Restaurant.

Here are url's to 3 systems, local to me, using this type of linking system:
http://www.kuggie.com/target
http://www.n8yib.com
http://www.shol.com/kuggie/ahra/hmft.html

Full Duplex?
A different method of linking sites, commonly used in larger link systems, like those of the Cactus Intertie (originally based in California but now in many states - see the map and realize that every dot is a fully functioning UHF repeater, and every line is a point-to-point full duplex link), NERA, and other larger systems use full duplex radio systems to accomplish their links. This type of system is likely better for full time systems if you can afford it. It's expensive because every link is just like running another complete repeater (remember it's duplex), so duplexers are often required along with modified radios that will operate full duplex for extended duty cycles. The controllers needed for this type of system need a duplex audio buss inside them and hence are complex and expensive (and in many cases are designed and built by the group themselves). Implementing this type of system (correctly) is not an easy task. This type of system *could* have the links transmitting all the time, but usually doesn't. This eliminates any 'lag' time for the system to become active, and usually sounds much better due to running "flat audio" throughout the system. There are articles on flat audio at this web site.

Here are url's to their systems so I'll not go into trying to explain them here - again:
http://www.cactus-intertie.org/ (see the map mentioned above)
http://www.qsl.net/nera/

Internet Linking:
The latest type of linking to hit the amateur scene is via the internet. IRLP, I-Link, EchoLink, app_rpt - Asterisk, TLB, and others have shown that the internet is a great way to connect repeaters together that have quite a distance between them (or poor radio path). All you need is to have access to a good internet connection at the repeater site, or a point-to-point link to a location that has it. Just realize that any natural disaster that affects the internet connection (i.e. the DSL goes down) will take out your link.

Here is information on those systems:

IRLP - Plus there is an IRLP page at this web site
I-LINK
Echolink
Echolink Boards
app_rpt - Asterisk
The Asterisk app_rpt Project

Linked repeater systems
Here is a list of sites for linked repeater systems that we know of. It is not intended as a all-inclusive list. All of the links below go to their own web sites. Send corrections, additions amd deletion requests to Mike WA6ILQ at (his callsign) /at/ repeater-builder /dot/ com

Alabama Inter-City Network uses 29 repeater pairs and remote bases to cover a large portion of Alabama. Interesting to note that the "repeaters" are operating half/duplex on repeater pairs. *OPEN*
Arizona Repeater Assoc. owns and operates 22 repeaters on 2, 1.25, and .70 meters in Arizona. Along with the East County Repeater Association comprise the CalZona Link. *OPEN*
Armadillo Intertie - Texas state-wide system with connections to the Cactus Intertie. **CLOSED** (available to members only).
Big Bend Amateur Radio Club site by Douglas S. Otoupal, N5HYD. They run a large coverage linked repeater system in the Davis Mountain region of West Texas. *OPEN*
Cactus Intertie covers large portions of California, Arizona, New Mexico, Nevada, Utah, Colorado and Texas. Additional coverage is now available in the Washington D.C and the surrounding area of Maryland, Virginia and West Virginia, Pennsylvania and Delaware, however it is not linked to the rest of the system on a full time basis yet. **CLOSED** (available to members and affiliate members only).
Colorado Connection employs fifteen repeaters to cover a large area of Colorado. *OPEN*.
Colorado Repeater Association is an amateur radio group providing voice and data services from 6-meters thru 1.2 GHz for hams in the Colorado Front Range. *OPEN*
Columbia Amateur Radio Club operates a wide coverage linked repeater system. The repeater system consists four repeaters in South Carolina. *OPEN*
The Condor Connection is a group of privately-owned, linked 220 MHz repeaters with coverage extending from below the Mexican border on the south to beyond Las Vegas and Phoenix on the east and to just below the Oregon state line in the North. *OPEN*
East County Repeater Association owns and operates 11 VHF and UHF repeaters in the Southern California area, with locations on most of Southern California's highest mountains, and coverage in both San Diego and Imperial Counties. Along with the Arizona Repeater Assoc comprise the CalZona Link. *OPEN*
Electronics Applications Radio Service (EARS) covers eastern Illinois and central Indiana. *OPEN*
Evergreen Intertie is a network of interconnected Amateur Radio repeaters though out the Pacific Northwest States. There are about 30 repeaters in the VHF and UHF bands. Each repeater is connected to a backbone made up of radio links. There are currently two main parts of the backbone. The first connects Northwest Oregon to Seattle (the North/South Trunk), and the second connects Seattle to parts East (the East/West Trunk). *OPEN*
Graham Repeater Association serves the region of Guilford, Alamance, Orange, Durham and Wake Counties, North Carolina. *OPEN*
Green Mountain Repeater System is composed of two repeater sites located on a mountain chain east of the city of Huntsville, AL. that runs in a roughly North-South direction. The sites are about 10 miles apart. *OPEN*
Hams for Emergency Radio Communications (HERC)The HERC system is a network of interlinked repeaters across the state of Wyoming. This system is useful from many areas and provides very important emergency communications capability throughout the state as well as a great way to keep in touch for travelers or folks living in different communities.
KF4TNP Repeater Group covers Marshall, Maury, and Giles Counties in Tennessee. *OPEN*
The Intermountain Intertie, also known as the Snowbird system consists of 17 repeaters and has coverage of Utah, south western Wyoming, southern Idaho, West Yellowstone Montana, and south eastern Nevada (the Las Vegas area). *OPEN*
The Intermountain Repeater Emergency Amateur Network is a collection of 4 repeaters covering northern Utah. It can be linked into the Sinbad system or the Intermountain Intertie. This linked system operates on the 222MHz band. It also features two remote base radios that can be brought up on the 2m or 70cm bands. *OPEN*
The Montana Repeater Link Association covers southern and central Montana with 7 repeaters. This is an open system and is supported by it's users. This linked system can link into the Intermountain Intertie. *OPEN*
MegaLink is a wide coverage system of 21 repeaters owned and maintained by Paul Choc, WA5IHL, in New Mexico. The Mega-link, together with the repeaters of the Upper Rio FM Society and the other affiliated repeaters comprise the Upper Rio Linking System. *OPEN*
Rocky Mountain Radio League owns and operates eight repeaters at four sites along the Front Range of Colorado. *OPEN*
The Sinbad Desert Amateur Radio Club repeater system covers most of eastern Utah and parts of Salt Lake and Utah counties. It consists of 9 repeaters. *OPEN*
The Tennessee Linked Repeater System covers a large part of Tennessee. **OPEN**
The Target Link System operates over parts of Pennsylvania, Maryland, Virginia, and West Virginia including parts of Baltimore and Washington, D.C. *OPEN*
Upper Rio FM Society operates 8 linked repeaters in New Mexico. At one time I listed this as a CLOSED system, however I believe this is changed. URFMSI appears to connected also to Mega-Link, which includes many of the repeaters from the now defunct ZIA Link. **OPEN??**
WR6AAC Repeater page with photos of equipment and sites, on 5,000 and 8,000 ft. mountain tops in California. Basically a 220 system using GE MVP's converted to 220 MHz. *OPEN*
Western Amateur Link Assoc. operates in California. Use of the system is provided for free, however access codes are limited to those who make a yearly donation of $50.00 US or more. There are links on their website to mods, manufacturers, and a truck load of URL's to outstanding sites! *OPEN*
West Texas Connection is a linked repeater system covering more than 20,000 square miles of West Texas. The system provides continuous coverage along Interstate 20 from the Fort Davis/ Big Bend area to Colorado City and from the Andrews/Seminole area south to McCamey. Coverage also includes Interstate 10 from the Davis Mountains past Fort Stockton. *OPEN*
The Western Intertie System or WIN System is a series of 71 repeaters that are linked 24x7 year around. Most are 440, or UHF repeaters, but they have some 2-meter and 220 repeaters as well, that cover a great deal of California, 16 States, and four Countries around the world (see this list). The WIN System is owned and operated by Shorty, K6JSI, with a lot of help. If you want to listen in just connect to the Streaming Audio. The "Insomniac Net" at 2300 Pacific time is fun to listen to (or join in), just connect to IRLP reflector 9450. The system is Member Suported but *OPEN* to guests and visitors.
Wisconsin Interstate System W.I.S. covers a large part of (what else) Wisconsin's Interstate system. Coverage also includes the Minneapolis/St. Paul, MN, area. *OPEN*
VE2RM The Western Quebec VHF/UHF Amatuer Radio Club.
Short Mountain Repeater Club (W4YXA) is on the frequency pair 146.31/91 located approximately 60 miles SSE of Nashville, Tennessee at an elevation of about 2200 feet. *OPEN*
SuperLink is an "on demand" system covering North Dakota, Minnesota and Wisconsin. *OPEN*

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Page created March 24 2003 by W3KKC

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.