Edmonton IRLP  &  Internet Radio Linking Project

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It was soon discovered that the "old" ICOM handheld had seen much better days and had numerous problems. Each time one problem was cured, two more seemed to develop and the radio would never be able to be counted upon to provide reliable service due to component and soldered connection failures resulting from old age and hard use. After countless hours of work, the radio was finally made acceptable for temporary service while a replacement radio was found and prepared.

February 2001  -  New WR-1454 Link Radio

The link radio is at the home of James, VE6SRV, who provides the IRLP internet connection. He had a UHF antenna available for the link radio, but being antenna poor this left him having to use a VHF antenna on his UHF handheld to communicate with the VE6SBR repeater for IRLP conversations. The combination of the handheld's low power plus the less than ideal 3rd harmonic UHF match on the VHF antenna resulted in James having a less than full quieting signal into VE6SBR. It did not make sense for James to have to transmit his signal 12 miles just to access the IRLP link radio sitting several feet away from him so I designed the new link radio for dual purpose use. It provides both, the link radio function for IRLP and also functions as a standard radio for James to use for local VE6SBR repeater access. This is accomplished with some special audio path switching.

To function as a standard IRLP link radio, the radio's receiver COS and transmitter PTT signals must be connected to the computers IRLP interface board. Also, the radio's input and output audio signals must be connected to the computers sound card. For James to also be able to use this radio as a standard radio, it has to be further modified so that -

1. When the IRLP node is active and James uses the radio to transmit to the repeater, the normal receiver audio fed to the computer must be replaced with the local mic audio and the receiver COS signal fed to the IRLP interface board must be replaced with the mic PTT signal so that the mic audio being transmitted to the repeater can also be sent to the IRLP system.

2. When the IRLP node is active and the radio is transmitting received IRLP audio to the repeater, the normal receiver audio to the radio's audio amplifier must be replaced with the received IRLP audio being feed to the radio's transmitter. In addition, the receiver COS signal that un-mutes the radio's audio amplifier must be replaced by the IRLP interface board PTT signal that keys the radio's transmitter so that the received IRLP audio can be heard locally.

The following photo shows the front of the modified radio spread open and the board wired into the radio that was constructed to provide the required COS, PTT and audio switching. For such a small board it is unbelievable how many interconnecting wires are required. The large gray conductors are the two 1/8" shielded wires to & from the sound card. The small gray conductors are the 1/8" miniature shielded wires used within the radio.

Also on the board is a relay for radio channel 1 / channel 2 selection, CTCSS tone encode/decode circuitry and a DTMF decoder that eliminates the need for a separate IRLP controller board.

Using IRLP, you only hear the messages of the node accessed, never the node that you are on.

For local users, the following buttons have been provided to play the node messages of
Edmonton VE6SBR repeater (node 1240) and Alberta SARA Linking System (node 1260).
(Note: The following buttons no longer work due to the way newer browsers work)