Background
Motorola’s R1225 repeater series is a unique series in the legacy of Motorola repeaters. While considered a base tier repeater, it was quite functional and quite adaptable and could be used for many purposes from standalone repeater to LTR with Passport. Even over 15 years since the repeaters ceased being sold they are still common place and revered by commercial and amateur radio operators alike.
To better understand the R1225, we have to understand how the Radius line came to be. In the mid-1980’s Motorola released their first base tier synthesized mobile radio, the Radius. While it would receive updates the Radius chassis and layout would guide what would become the Radius series for nearly the next two decades. As most synthesized radios were not capable of running in full duplex, there was a need for a matching budget repeater for the line. Out comes the Motorola R100 wall mounted repeater. This was a simple repeater based on the receiver and transmitter circuitry used in the Radius. The Radius’ mid-tier brother was the Motorola Maxtrac which for all intents and purposes was the same radio with an expanded logic board. The expanded logic board would allow for trunking support, more channels and was even offered on more band offerings.
The Maxtrac would receive some upgrades in the early 1990’s, most notably the addition of a 16 pin (an upgrade from the 5 pin) accessory connector which added functionality for RX audio, TX audio, PTT and COR among other things. As all of the signalling nessecary to build a repeater from two radios were now present, a simple repeater could now be created with the use of Motorola’s Repeater Interface Communications Kit (or RICK). As the R100 was getting long in the tooth, Motorola decided to package the successor to the Radius, the GM300/M120/M10 in a housing with a controller (commonly the RICK but there were also some built for Motorola by Zetron controllers such as the i50R and i750R) as a turnkey low tier repeater solution with duplexer and power supply. These were commonly packaged as the desktop GR300 and wall mount GR500 repeaters. As the 1225 line was announced to succeed the GM300 and SM120 lines, a new repeater was created. A full duplex repeater with integrated controller, it was named the R1225 and was housed in a Radius chassis with various heatsink designs depending on the RF output capabilities. These were offered in a desktop (GR1225), 19″ rack mount (RKR1225) and individual (R1225) variants with the latter being only the full duplex module. As the R1225 didn’t have a control head, it had no way to turn it on or plug in a standard Radius mobile programming cable…so how do you work with the blasted thing?
Working with the R1225
The control head for the RKR1225 and GR1225 plugs into header pins under the front cover of the R1225 via a ribbon cable, so lets start by removing the cover on the header pins.
Anyone who’s ever taken a Radius/Maxtrac/GM300 control head apart…knows that this looks extremely similar. Marking the header jumper’s location (which simulates the closing of the power switch) we can remove that and then using the service manual for reference, take a look at what those logic board pins are actually used for. What we find is that they are identical in function to the logic board pinout used on the Radius/Maxtrac/GM300 radios. Since the mobile control heads are mostly backwards compatible (and it’s not uncommon to find a GM300 with a Maxtrac control head or a Radius with a GM300 control head that were simply repaired and refielded from the carcasses of other radios that were laying around) I wonder if a GM300 control head will work on the R1225. Let’s find out.
Now for the important question, does it turn on?
And we even get noise. Before we go further, yes I know there are failed segments on the display…remember my comment about the carcasses of failed units on hand? What kind of radio guy would I be if I didn’t have parts radios laying around?
As I actually have done this before professionally and it’s a pain to carry a spare control head around whenever you need to mess with these (companies like Bearcom have entire rental fleets based off the compact R1225 still), I decided this go around I was just going to make an adapter for power/programming purposes so I got busy removing the volume/microphone board from the control head. Very simple, remove the volume knob, and unscrew the Torx screw which retains the board in the head via a metal clip and screw holding in a plastic retainer clip and the entire board comes out of the control head.
There are two wires which need to be removed from the plug. In all cases I’ve seen, these are red but YMMV. They go directly to the internal speaker an are essentially 110 block pins with the wires simply punched down. As I have a full service cable for the 16 pin accessory, I can do just about anything with a RLN4460 box via the accessory cable on the back of the repeater so the loss of the speaker isn’t important.
Now the Volume/Microphone board can be used as a simple (and small) programming/service adapter for these repeaters and as they rarely go bad…pretty easy to dig up from a parts radio.
Programming the R1225
Programming the R1225 is fairly straight forward. All you need is a copy of the last version of the 1225 RSS (Version 4.0 written for Windows XP) which was one of the first unified RSS packages that handled an entire line (mobile/portable/repeater) that Motorola produced and something that would later be followed by the successors to the 1225 line, the commercial and then the TRBO lines, a 32 bit version of Windows (XP/Vista/7/8/10) and a programming cable. RIBless works fine, USB works fine (assuming you have good drivers).
For a quick example on programming these repeaters, see my Youtube video where I walk through programming one for GMRS in real time.
