About the 442.15 repeater in Austin

Output frequency is 442.15, +5 Mhz split with input frequency 447.15Mhz, PL tone 186.2 Hz.
Repeater identified by AA5BT/R
EchoLink node #136958, identified by K5AXW-R
AllStar node #28856, identified by KD5EUO
Trustees: Los Chupacabraderos


The 442.15 repeater system is run as a benevolent dictatorship. Experimentation with other support and control systems has shown us that our current system results in the smoothest operation. It is an open repeater system, and all licensed amateur operators are encouraged to participate.

Financial support is accomplished by the core group financing the majority of equipment costs. These are actual equity holders in the system. Donations of lesser amounts are taken by active users as the needs arise. These smaller donors are non-equity holders in the system.

The trustees are ultimately responsible for the legal operation of the system. The system is registered through the Texas VHF FM Society. The trustees encourage freedom of speech, debate and discourse on any topic with free and un-fettered communication of ideas and philosophies between all system users. We feel we can serve the community best -when users feel comfortable to express their thoughts in a healthy and supportive environment. Normal rules of decorum and mutual respect are to be observed. The trustees reserve the right to bar any station from using the system without prior notice.


The 442.15 system consists of two repeaters. The UHF system is based around a Yaesu Vertex-5000 commercial repeater. It is running 25 watts out -through a pair of Wacom BpBr -90Db duplexers with 74 feet of LMR-600 to a Diamond X700HNA +13DBD Omni directional antenna at 750′ MSL. It is located at the University of Texas at Austin. The system also uses a Phelps-Dodge pre-selector cavity and HP GaAs FET preamplifier. This system is fully battery backed-up with a 100AH deep-cycle cell on float charge.

The repeater’s technical operating characteristics are constantly monitored and optimized. It is operating at the UHF noise floor and its TX power is exactly matched to the RX sensitivity. Several custom modifications have been made on the repeater to improve audio characteristics and overall operation.

This is first repeater in Austin to feature the Echolink Internet linking system. It was implemented February 21st, 2002  after a few days of fabrication and de-bugging of the micro-controller interface board. The hardware is a dedicated P-III 450 on a 100 base T ethernet connection -running into the PIC microcontroller interface- which feeds a T-81a HT -powered by a lambda switching PS. The duck only has to cover 1000 ft to the repeater.

The codes are as follows:
00 — Random connection to simplex station
01 — Random connection to Repeater -not recommended
05 — Kill Ilink for 10 minutes
* — Play Ilink announcement
# — kill Ilink connection

Contact a trustee if you would like to use the Ilink system (security access code)

Usage protocol: Take it slow like on HF. There is about a 5 second turn around time. Some international stations cannot speak English fluently; please remember to delete colorful sayings and colloquialisms from your speech. We are representing the USA internationally on this system, and so remember that a good impression reflects on your country…act accordingly. This is citizen diplomacy.

Get the Echolink software here.

Budget and operating history:

Spring 2001 antenna upgrade:
Received $590 from generous donors. Funds went to:
Diamond Antenna – $339
Coax – $82.40
Connectors – $45.21
Hardware – $64.17
TX VHF-FM Dues $10.00
Total $540.78

Feb. 20th, 2002: ILINK was installed. Microcontroller was $46. Case and connectors were $15.35.

May 2002: We moved the 442.15 into air conditioning in late April due to fuse blowing. We purchased 80 ft of LMR-600 and 200ft of guy rope for $131.00. Cost was covered by AB5N, K5AXW, WB5TXW, WX5U.

July 2003: Implemented stage one of a receive sensitivity upgrade and have increased RX sensitivity by 6DB. We separated the RX and TX antennas and installed a homebrew 6DB gain collinear antenna- 30 ft. higher than the RX antenna. Second stage is adding a second preamp at the RX antenna. Computer model analysis shows that we could stand a little more gain right there. RX is better than TX now. You can expect to hit the machine FB using 100mw anywhere in the bowl of Austin. Cost was about $285. Donations came from these people, to which we give thanks:

KD5QIC — $40
N4WJP — $100
KD5SFL Deb and Mark — $100
N5WU Sam — $100
Glenn KD5MFW — unspecified amount.

November 2013: An AllStar link has been established on the 442.15 repeater. The node number is 28856. This link enables the repeater to be linked by VOIP to other repeaters, and for users to access the repeater by VOIP phones. The link is hosted by KD5EUO and consists of a Yaesu FT-7800 and Astron SS-30M power supply (both donated by KC2QJA at a value of $300) linked via a URI cable fob and URI USB radio interface to an Intel Atom-powered PC running Acid CENTOS. Antenna is a four-element 70cm yagi pointed at the repeater. Remaining parts purchased for $300 by KD5EUO; total value is $600 for this node.

December 2013: A remote repeater node has been established in far northwest Travis County and is linked by AllStar to the 442.15 repeater at UT. Its purpose is to extend the range of the original repeater. The frequency is 442.1 both input and output…it is a simplex node. PL is 186.2. Its AllStar node number is 29010. It is comprised of a Yaesu FT-7800 and Astron SS-30M power supply, linked via URI fob and URI USB interface to an HP PC running Acid CENTOS. Antenna is a dual-band J-pole at 960′ MSL near the intersection of US183 and Anderson Mill Rd. Effective radius is approximately 5 miles. All parts and labor provided by KD5EUO at an estimated cost of $500 for this node.

Leave a Reply