Radius Gr1225 Repeater Manual Motorola Gr1225 Repeater User Manual - The Joint Boulder GR1225 prevents transmissions over your repeater with-out proper ID or “squelch codes”. Power is adjustable by channel Each channel can be programmed to a different power level, either 1-10W or 25-45W (UHF) and 1-10W or 25-50W (VHF) to meet your Page 3/10. Motorola GR1225 repeater issue. Discussion in 'VHF/UHF - 50Mhz and Beyond' started by AD0MI, Jun 21, 2015. Do you have a Service Manual for this UHF repeater? Gr1225 Repeater User Manual - thepopculturecompany.com This is a Motorola GR1225 UHF repeater, model number M44GRC90C2AA. These are 40 watt, 16 channel repeaters with a band split of 446-470 Mhz. Repeater comes mounted in a GR500 housing which provides continuous duty cycle (100%) and comes complete with internal duplexer. Free Motorola Gr1225 Repeater Manual build a repeater by nearly a third. This stylish, compact, desktop unit relies on a single, full duplex transceiver to transmit and receive. Radius GR1225 Repeater - Industrial.

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Using the Motorola GR1225 as a Repeater
By Don L. Blanchard - WA7GTU
IRLP Node 3574
Edited and HTML'd by Mike Morris WA6ILQ

Note from the editor:

The R1225 is a continuous duty radio (about the size of a MaxTrac) that has two antenna connectors and will work in full duplex mode, and 25w continuous duty at that! The GR1225 is that radio in a box with a power supply plus two options: a duplexer and an advanced controller (the sales brochure is here). The GR1225 was designed to be the continuous duty model in the the GR300 / 400 / 500 line of prepackaged repeaters, all of which were intended for low-duty-cycle full duplex applications like a shopping mall security department repeater, or other low-end non-public-safety repeating applications. The GR1225 configuration parameters allow it to be programmed as a repeater or as a non-repeating full duplex radio and that, coupled with the continuous duty design makes it ideal as a point to point link, and much better than a Maxtrac or GM300 mobile, neither of which can duplex, or run continouous duty. The R1225 / GR1225 also has a fairly decent internal controller where the GR300 / 400 / 500 series required the RICK box to do that. The optional advanced controller could be one of four, and an autopatch was available (see the sales brochure link above).

The Internet Repeater Linking Project is a worldwide informal group of amateur radio repeaters that are linked using VoIP (Voice over Internet Protocol) systems. More information on IRLP is available at http://www.irlp.net. Each repeater in the IRLP network is connected to the internet through a PC running the IRLP system program, with runs on the Linux operating system. The computer is treated as if it was a link radio, with audio in, audio out (via the sound card), COR and PTT (via pins in the printer port). The IRLP interface board that plugs into the printer port has the necessary interfacing circuitry, including a hardware touchtone decoder. The board can be jumpered for simplex or full duplex operation, and if you have a full duplex environment you really want to set the jumper to match. A 'Node' in the IRLP system is one computer and repeater system.

The ideal IRLP situation is where you have an internet connection at the repeater site and can connect the node computer to the repeater controller directly (as if it was a second radio). Since very few repeater sites have an internet connection many connections use the second-best option: a point-to-point radio link (on UHF, 900 MHz or 1200 MHz link frequencies) between the repeater site and a location where the node computer and internet connection is actually located. Others use the third-best option: they set up the node computer and radio as if it was just another user on the repeater.

This article describes how WA7GTU set up a Motorola GR1225 radio as a local repeater, with an IRLP node connected to it. The same GR1225 if programmed differently could also function as a 'ground level' end of a point-to-point link, i.e. set up as a non-repeating full duplex base station.

There are pages at this web site that cover the RSS and RIB in detail.

IRLP Node 3574, located in Cedar City, Utah has been operating with a Motorola Radius GR1125 Repeater on the 444.900 ‑ 449.900 MHz frequency pair for a couple of years. There have been a number of inquiries as to how it was interfaced with requests to make the information available on the Internet. The following document is an attempt to answer those inquiries. It is believed that the mobile GM300 is basically the same radio and the following information should apply to both models, however the GR1225 will run full duplex, whereas the GM300 is a 'normal' PTT radio.

There are several models of the GR1225, and the product line includes models that cover both the 146 to 174 MHz and 444 to 474 MHz frequency ranges with differing power levels. The 146-174 models can be 'stretched' down to 145 MHz, and the 444-474 models can be stretched to 440 MHz.

The first thing that you need to know is that the GR1225 has to be programmed using the appropriate Motorola RSS software, so you either need to know someone with the hardware/software or have good rapport with your local Motorola dealer. The hardware/software is of fairly old vintage and hopefully it is still available in your area. The radio programming software is DOS based and will not even work on today's faster computers. The programming is done through the microphone plug with a computer interface called a RIB. There are diagrams of these interfaces on the Internet, but getting the software is a problem. Please see the RSS page in the Motorola section at this web site for details. The second thing that you need to know is that the 450 MHz version of the GR1225 will program no lower than 444.000 MHz without modification. The 3574 node repeater is operating within this frequency range, so no attempt was made to look into what modification would be required to go lower in frequency, but it probably can be done.

The GR1225 is a small self contained repeater (see photo below) that can be programmed to 16 different frequencies. The 3574 node repeater is also programmed to a second frequency of 444.500 - 449.500 MHz which is another frequency pair coordinated for this area. The built in duplexer handles this second frequency reasonably well with very little degradation, but this frequency is only there as a backup and adding it to the programming took less than a minute. The repeater operates from a built in switching power supply and there is a fan integrated into the housing for cooling. It often operates for hours at a time and there have had no temperature problems. The fan is temperature controlled and does not come on very often. The model in operation is a 10 watts version. The author also has an older 25 watt version as a spare, but has not yet tried it on IRLP. It is all programmed, but some of the connections on the Accessory Connector need to be rewired.

Below is a reproduced page from the GR1225 Service Manual explaining a bit about the available connections in the accessory connector on the rear of the radio. The fuctions of a number of the pins are programmable.

Expanded Accessory Connector

R1225 Transceiver Service Manual

Programmable Pins
Pins 4, 6, 8, 9, 10, 12, and 14 on the accessory connector are programmable. The function of each pin can be assigned using RSS. Information on the available functions and how to program them is contained in the RSS help screens and in the files in the Appendices section.

Pin 4 is an output only. It provides an active high to the 13.8 V dc supply (0.25 Amps maximum), otherwise it is pulled low via 10k ohms.

Pins 6, 10, and 9 are inputs only. They are normally pulled high inside the radio to 5 V dc via 4.7k ohms. To activate any of these input pins, it should be pulled low to within 0.7 V dc of ground.

Pins 8, 12, and 14 may each be programmed as either an input or output. If programmed as an input, the pin is pulled high to 5 V dc via 4.7k ohms. To activate the input, it should be pulled low to within 0.7 V dc of ground. If programmed as an output, the pin is normally pulled high to 5 V dc via 4.7k ohms. When enabled, the output goes active low. Maximum sinking current is