Austin Amateur Radio Club Repeaters Systems
2017 marks an exciting time for VHF and UHF communications in Central Texas. Amateur Radio repeaters are playing a large part in the growth of the hobby and the interest in new technology relating to communications. Amateur Radio’s continued focus on emergency communication has also contributed to interest in repeater communications.
The Austin Amateur Radio Club (AARC) has enjoyed a good relationship with several benefactors over the past twenty-plus years that has given the Austin Amateur community a foundation making extremely good VHF and UHF communications possible in the Central Texas area with the repeaters the AARC operate. The year 2016 has seen a continued growth of community sponsorship of AARC repeater activity. What follows is a summary of each site where the AARC has operating repeater assets. There are also some comments of what could be done to improve coverage or functionality by taking some steps that are reasonable based on the site constraints.
City of Austin Site at Mt. Larson
This location has a run of 7/8 inch hardline that is about 200 feet long and a DB-224 antenna. There was also a VHF duplexer at this location. These three items were at this site to support a FM repeater operating on 146.78 MHz. This location has a tower that was built by the City for various UHF and VHF radio systems. The self-supporting 300 ft. tower supports AARC antenna and feedline. The need for a VHF repeater frequency for the AARC D-Star system prompted an arrangement with Ross, N0GSZ to keep this site operational. The AARC moved the 146.78 MHz Texas VHF Society coordination to the D-Star repeater in South Austin. The AARC radio equipment and duplexer was put in storage and Ross provided a VHF duplexer and Motorola Quantar P-25 repeater. This system is now operating under the callsign of N0GSZ and is using the AARC antenna and transmission line vacated by the old 146.78 AARC repeater. The Austin amateur radio community now has open access to a P-25 repeater on 146.86 MHz and the AARC D-Star VHF repeater at the South Austin Medical Center is operating on a coordinated frequency.
Recommendation: Keep our relationship with the City of Austin Wireless Department positive in order for the AARC to maintain a position on this tower and in this building rent free. The position and height of the tower provides excellent downtown coverage using N0GSZ equipment operating in mixed mode (FM/P-25). This is a desirable location for the amateur community. This site could also be used for a secondary receive location that could provide easy linking to Buckman Mountain. There is some degraded performance of the antenna or transmission line due to age or water damage. Further evaluation of the exact nature of what is causing poor VSWR on the line is needed. This site’s building and tower has a large potential for growth due to the City of Austin removing a large number of radio systems housed at this location.
Pickle Research Center (PRC)
The tower and building we occupy supports the 146.88 System Fusion repeater and 444.10 FM Repeaters. The land is owned by the University of Texas at Austin and leased to the LCRA for site management. The tower is a 300 foot guyed facility built in the mid-1990s. It also supports microwave and digital trunk radio systems operated by the LCRA in the 700 and 800 Mhz. bands. There is a UHF duplexer and NHRC-5 controller supporting the GE MASTR PRO repeater running 35 watts TPO. The VHF repeater is a Yaesu System Fusion DR1(X) running 25 watts TPO. There is a UPS providing backup power and AC line isolation for the VHF repeater at the site. The antennas and transmission line for these two repeaters were new in 1998 and were provided by the LCRA. The antennas are at the 275 foot level of the tower. The building is heated and air conditioned and has been recently renovated to provide a clean and secure housing for AARC equipment at no cost to the AARC.
Old GE MASTR Pro repeater gear that was supporting the 146.88 MHz repeater and the controller for this site were gifted to the Milam County Radio AARC this past year.
444.1 Repeater – Reliable system. Minimal maintenance is required for this repeater. Good commercial power and tower grounding has provided a good home location for our equipment. Roy, WA5YZD, replaced the old UHF repeater made from a modified mobile radio with a GE Mastr Pro in 2008. This hardware was restored to like new status. New tubes and many new components were purchased for the system. The receiver and transmitter were calibrated and aligned to provide excellent repeat audio quality and very good system availability. The AARC purchased a controller made by NHRC to go with the MASTR Pro UHF radio hardware WA5YZD refurbished and donated. Reliable coverage for Central Austin, North and Northeast Travis County is provided by this site. The transmitter is producing 35 watts out of the duplexer to the feedline. Receiver sensitivity is .35 uV for 20 db quieting.
146.88 System Fusion Repeater – This system has been operating reliably for about a year. The repeater was connected in January, 2017 to the Wires-X network using a HRI-200 Wires-X appliance, PC running Windows 10 with transmission line and antenna provided by Roy, WA5YZD, to the AARC. A FT-400D radio on loan from Don, AC5YK, is providing the RF link to the repeater site. The Pickle Research Center Site does not have broadband connectivity. As a result, a RF linked Wires-X node is located off-site. The node is currently hosted by WA5YZD using internet connectivity provided by WA5YZD.
The repeater is connected to the Texas-Nexus Room by default giving it access to several repeaters spanning from San Antonio to the Dallas/Ft Worth area. The repeaters in distant cities in this network (Room) are fully linked to the Austin 146.88 repeater. Wires-X features are not available when the Austin user is operating analog FM. When users are running their Fusion radio in the digital mode, all the features of Wires-X are supported. The Austin 146.88 System Fusion repeater operates in an Automatic Mode Switching configuration that repeats FM if the user is transmitting a FM signal. If the user has a System Fusion compatible radio and operating it in the digital mode, the repeater will repeat the signal in digital format and a full Wires-X feature set is available to the user.
The Austin users with Fusion digital radios are able to connect the repeater to any Room or Node in the Wires-X network that is open for a connection. After 30 minutes the WA5YZD-ND node will reconnect to the Texas-Nexus Room.
Recommendations: If the AARC wants to continue to use the features of Wires-X and System Fusion, a radio, HRI-200 appliance, PC, antenna and transmission line should be acquired by the AARC. A site with internet broadband in coverage range of the repeater is also needed to host the node. The site needs to be attended due to need for occasional hands-on attention required for the PC based Wires-X application. Off-site hosting of the node is recommended at this time due to the need for quick and easy access to the PC hosting fast developing Wires-X application.
Buckman Mountain – KLRU/KVUE/KEYE Tower
The Austin Repeater Organization gained access to the original KVUE-TV tower and KLRU-TV building in the early 1982 due to the relationship Sanford Musgrove (W5FIT- SK) had with the two stations at the time. The 146.94 Repeater and the 224.80 repeaters were housed inside the KLRU-TV transmitter building. In 2011 the KVUE analog tower was removed from the site. KVUE and KEYE agreed to allow the AARC to move antennas onto the jointly owned tower that is located on this site plus the addition of a UHF repeater system antenna. 660 feet of 1 ¼ inch hardline and antennas were acquired by the AARC to support the move activity. Rack space was provided by KVUE in their building for AARC hardware.
All three AARC repeaters share the single feedline to the 500 foot level of the tower. The AARC owns duplexers, controllers and couplers at this site to provide exceptional coverage of Travis County and parts of surrounding counties.
444.2 Repeater – A UHF MASTR II repeater was donated by KVUE and added to the two repeaters that existed at the site. The Austin Repeater Organization had a coordination of 444.2 that was transferred over to AARC for this site from a location in South Austin.
In 2016 KVUE provided the connection to a UHF antenna the station has at the 950 foot level of the tower for use by the AARC 444.2 repeater. A MASTR II remote receiver was acquired by donation from Paul, KE5ZW and placed in the building at the top of the tower. This shared use of a KVUE antenna providing commercial communications for the TV station is the result of strategy and planning that took over 6 years to materialize.
Chuck, W5PRO, has provided an Asterisk server located off-site in Central Austin and client micro-computer that is connected via a DSL internet service to the 444.2 repeater. Many Hams in the AARC have been given station numbers on this system as a test platform. The system has proved to be a successful project. The system can provide users access to the 444.2 repeater via 3G and 4G Smartphones. PCs and MACs connected to the internet running the Linphone Asterisk application are also able to connect to the system. WA5YZD has picked up the monthly DSL broadband connection cost for this part of the system.
January of 2017 also marked the addition of the Allstar network to the 444.2 repeater. WA5YZD provided a site to host a node controller and N0GSZ provided a UHF link radio to make the link operational. Tom, K5TRA, provided technical assistance and guidance to configure and get the Allstar node into service. The 444.2 stays connected to other Allstar nodes in the Travis County area on a full-time basis thus expanding the wide area coverage repeater even farther.
Operational Status: This repeater is working reliably and all features are functional.
Recommendation: Service or replace the upper triband coupler located at the 500 foot level of the tower. This will reduce loss of transmitter power going to the transmit antenna. This is a recommendation that is common to the 146.94 and 220 repeaters and will benefit all three repeaters.
146.94 Repeater – Repair was made to the lower triband coupler in late 2016 with the help of Ken, K5UHF and Mike, WA5VTV. Coverage is good but can be improved with some attention to the upper triband coupler at the 500 foot level. Suspected detuning of the upper triband coupler may be affecting performance due to losses in the coupler. Performance of the MASTR II VHF repeater supporting this system is exceptional. Long feedline and coupler losses are a concern together with some tower interaction with the antenna.
Recommendation: Repair or replace the upper triband coupler. Investigate the placement of the antenna based on suspected antenna beam tilt and interaction with tower that is causing some coverage problems. All components supporting the 146.94 repeater are operating reliably and overall coverage is exceptional at the time of this writing.
224.80 Repeater – Two separate Icom IC-38A mobile radios make up the receiver and transmitter of this repeater. The controller was designed by Fred Neuenschwander (W5FQR) and built by Charles Rich (WA5ESR). The transmitter makes 11 watts out of the duplexer to the feedline. The receiver is .25 uV for 20 db quieting. This repeater uses a duplexer and shares the same transmission line with the 146.94 and 444.2 repeaters.
This repeater is fully operational and reliably working.
Recommendations: Service or replace the upper triband coupler.
1.2 GHz Repeater – George Harvey (W5NFC – SK) and a group of other Hams had a repeater at Mt. Larson on a very low tower installation. It provides little use to anyone at the time it was located at Mt. Larson. The AARC is now the beneficiary of this repeater. It has been put into a waterproof outdoor cabinet and moved to the KVUE/KEYE tower. The callsign is N5MHI. It is located at the 900 foot level of the tower using separate antennas for transmit and receive. The frequency is 1292.4 (-20 MHz offset) and uses a tone of 107.2. This repeater offers coverage to the Travis County area and extends into surrounding counties. Antennas and feedline were also donated by the previous operator of this repeater.
Operational Status The repeater appears to be cold natured and has the tendency to key and un-key in really cold weather. There are some problems with sub audible tone and the controller at random times. Sensitivity of the receiver good and the power output is a stable 10 watts.
Recommendations: The 1.2 GHz repeater needs to be taken down from the tower to fix the temperature key-up problem. It also should be modified to transmit tone only when the user is keying the repeater and not during ID or hang-time period. Interest to connect this system to the Allstar network is very high due to 900 MHz repeater network growth.
South Austin Medical Center Hospital
This site hosts the AARC D-Star system operating on three bands.
Module C – 146.78 MHz (-.600)
Module B – 440.65 MHz (+5.0)
Module A – 1293.1 MHz (-20.0)
Module DD – 1294.5 MHz (Simplex)
D-Star at this site works through a single run of ½ inch flex hardline to a triband antenna. The transmission line is about 70 feet in length. The 3 digital voice RF modules and the digital data module are connected to the transmission line using a duplexer and filter network. SAMC provides the AARC with internet broadband service. There is a small form factor Dell PC running the applications that support the D-Star gateway.
The site also has a UPS that will run the system for about 30 minutes if commercial power is lost to the rack. There is a second 70 foot run of ½ inch flex transmission line from the AARC rack to the tower with a Cush Craft 2M Ringo antenna attached to it. A tower was installed on the Hospital roof by SAMC that support AARC antennas and the SAMC radio system.
Operational Status: The system is working reliably on all bands and with all four modules in service. The range on Module C is the best for good coverage in the Austin area. Module B is coverage is close to the same as Module C but not a complete coverage of the Austin metro area. Module A digital voice and digital data coverage fair but limited to Central and South Austin. Some hill top coverage to the west has been reported.
Recommendations: Split off the Module A 1.2 GHz DV and DD part of the system from the current feedline arrangement. Install a separate 7/8 inch transmission line to support 1.2 GHz to reduce the losses that exist due to feedline and couplers. Install a separate 1.2 GHz band antenna. Feedline has been donated for this project.
This report is provided with the best information available at the time of writing. Please contact me with your comments and questions at WA5YZD (at) ARRL.NET or any of the AARC officers using address found on the AARC website.
Roy E. Walker