A simple 2 meter repeater. Receives one frequency and retransmits 600 KHz above or below.
Duplexers filter frequencies so only TX frequencies pass on the transmitter side, and only RX frequencies pass on the receiver side.
This is the Elephant Mountain repeater. All BBARC 2-meter repeaters are installed in this manner. For this discussion, we will assume duplexers exist between any repeater and the repeater antenna.
In order to expand the system, we first add an external controller. Again, all BBARC repeater sites are designed this way.
To add remote sites to the system, we must have a way to link them. So we add a 70 cm ‘Link Repeater’. We could link to the 2 meter output, but that leads to issues of interference. We use 70 cm for linking, but 1.25 meter is also used in some systems. In 70 cm we refer to it as a 440 or a 420 link. 1.25 meters would be a 222 link. These refer to the frequency in MHz.
2 Station Linked Repeater System Our ‘Hub’ station can talk and listen at the same time, on both bands. Our ‘Remote’ station can talk and listen on 2- meters. It can only talk or listen on the 440 link.
Hub station when there is user traffic on the remote station. Someone is talking on the remote 2-meter station. That 2-meter repeater retransmits the signal and the controller also passes it to the 440 link radio. Here at the hub, the 440 repeater hears the link signal and retransmits it on 440. The controller passes the signal to the local 2-meter repeater for output.
Since the hub’s 440 link is a repeater, it can hear the transmitting site and repeat the signal on the 440 output so other sites can hear the signal and transmit it on their 2-meter repeaters. In this way, the number of remote sites we can add is limited only by how many coordinated frequency pairs are available, how much real estate we can gain access to, and how much money we have.
Let’s add a Telephone Patch to our Hub. Controller A is a simple controller. Controller B has a built in phone patch. We connect the phone patch to a land line and connect the controller B output to one of controller A’s inputs.
We also want to link to the West Texas Connection. We use a remote base radio for the link. Controller B can control the remote base radio.
Finally we add the SAME Weather Alert Radio to Controller A. SAME is Specific Area Message Encoder. Where are Hector and Juliet? They live inside controller B.
POWER SOURCES FOR REPEATER SITES All of our remote sites use storage batteries for a power source. Solar panels are connected to the batteries through a ‘Charge Controller’ to keep the batteries charged. All equipment at our hub site, except for the 2-meter repeater, run off batteries. At this site we keep the batteries charged with a power supply connected to Grid Power. The 2-meter repeater only runs from Grid Power. Therefore when we lose Grid Power at the hub site, everything continues to run off of the batteries, but the 2-meter repeater goes off the air. The controllers and the link repeater run off of the batteries, so all of our sites stay linked.
BBARC Repeater System 146.620-, McDonald Observatory, Ft. Davis, Texas 146.720-, Twin Sisters Mountain, Alpine, Texas 146.820-, Christmas Mountain, Terlingua Ranch, Texas 146.920-, Glass Mountains, 13 mi. east of US67 near Brewster/Pecos county border HUB REPEATER SITE 147.020+, Elephant Mountain, 23 mi. south east of Alpine
440 LINK FREQUENCIES The HUB link repeater transmits on 448.000 MHz. The HUB link repeater receives on 443.000 MHz. All Remote Site link radios transmit on 443.000 MHz. All Remote Site link radios receive on 448.000 MHz. All BBARC repeaters and link radios use 146.2 Hz PL tone.
HECTOR’S MESSAGES The following messages can be played back on demand by keying your mic and entering the corresponding numbers. Key In:Message: 30“Welcome to the BBARC Repeater System.” 33“Hi!” 34“2 Meter net tonight at 8 PM.” 35“146.2 PL may be in use.” 36“Meeting tonight at 7:30 PM.” 37Plays the Hector and Juliet argument. 38Time announcement (the clock is not correct.) 39Time announcement (the clock is not correct.) 5xx…Enter 5 and any digits you choose and Hector will read back everything entered after the 5.
HECTOR’S MACROS Hector’s Macros control how the automatic announcements and other items are controlled. 961Hector will respond “M1”. On system wake up Hector will greet with “Welcome to the BBARC repeater system.” then the CW ID clock will be started and Hector will announce “146.2 PL may be in use.” periodically. 962CW code “M2” will be transmitted. There will be no voice announcements from Hector. Only CW ID’s will be automatically transmitted. 963Hector will respond “M3”. On wakeup Hector will greet with “Welcome to the BBARC repeater system.” then the CW ID clock will be started and Hector will announce “2 meter net tonight at 8 PM.” periodically. 965Hector will respond “M3”. On wakeup Hector will greet with “Welcome to the BBARC repeater system.” then the CW ID clock will be started and Hector will announce “Meeting tonight at 7:30 PM.” periodically.
WEST TEXAS CONNECTION LINK No DTMF codes, Hector announcements, CW ID’s or Weather Radio transmissions are passed to the WTC link radio. Even though these things will be heard on the BBARC repeaters, they will not be heard on the WTC. If you want to turn Hector off while linked to the WTC, put the system in Macro 962 (CW ID’s only) before you bring up the link. One of the things 962 does, is turn off the remote base radio that we use for the WTC. 102 brings up the WTC link for receive and transmit. The response from the controller will be “Transmit.” in CW or Hectors voice depending on which Macro is in effect. 103 Turns the WTC link off. The controller response will be “Off.” 101 Turns the link on to receive only. It will not transmit anything to the WTC. The controller response will be “4.05 minus.” when activated.