Batboard

Hi everyone!

I'm setting up a UHF GR300. This particular unit is totally original with 2 GM300 radios and a simple RICK controller. I wish to use a different controller but want the ability to return to original if needed.

I have the GR300 setup/service manual, and if I understand it correctly then I should just be able to connect my controller to J4 (ACC) on the RICK, and leave the repeater enable button on the RICK turned off so that the external controller takes over.

Looks like all of the signals which I need are there on J4. This would be a great if I can do it this way because then the tx & rx cables to the radios are already in place and I can quickly return to original just by unplugging the external controller and re-inserting the shorting plug.

Thoughts are appreciated as always and thank you .

- Darrell/K7LZR

Yes. I'm currently doing this on a GR300 with an old Link Comm RLC-2. You have to disable the internal repeat path of the RICK, I believe the manual details how to do this. Then you make the connections to J4 with your external controller.

If you don't disable the repeat path, you'll have two repeat paths and things on your external controller (DTMF mute, repeater enable/disable, for example) won't work.

Thanks! I'll be sure to disable the other audio path.

Let us know how you made out, and any caveats you come across. It's been a LONG time (10+ years) since I've done this, but I know it works, as I still have the configuration I did 10 years ago on the air and working without issue.

Okay, got it working . Inside the RICK, turn S2-7 ON and S2-6 OFF. The RX audio at J4 pin #11 is gated audio and so is switched with the incoming signal. Seems to work fine although I would have preferred unsquelched audio. The audio source is still from the RX radio discriminator so no worries there.

All needed signals for an external controller are indeed available at J4, and if you have a RICK, i20R, or similar controller with radio cables already in place then it makes a convenient and dead simple way to interface.

Pin #11 is RX audio

You can access TX audio at either pin #2 (mic) or pin #5 (flat) depending on your needs.

Pin #3 is PTT (low) and pin #8 is COS/CTCSS (goes low) depending on RX radio programming.

Pin #7 is ground.

In my case, I'm upgrading to a much smaller system from a homebrew Mitrek based system which has given 10 years of reliable service but is housed in a 6ft. tall rack and is just way to big/heavy for its new desktop location. The controller is a PC with custom one-off software and has also been running trouble free for many years.

I also was a little concerned about TX duty cycle with the GR300 after reading various pieces about it but in their sales brochure, Motorola does say 100% at 25w with genuine 16ch. GM300 radios and a properly working fan.

My unit has 10w GM300 radios and I've tested it with keydown at the full 10 watts into a Bird Termaline for 2+ hours twice with no overheating nor power dropping issues.

Anyway, thanks again and hope this helps someone who is using this equipment

jistabout wrote:The controller is a PC with custom one-off software and has also been running trouble free for many years.

I'd like to hear more about this...

d119 wrote:

jistabout wrote:The controller is a PC with custom one-off software and has also been running trouble free for many years.

I'd like to hear more about this...

I'll be happy to provide details as soon as I get time to sit here & do so, likely within the next few days

d119 wrote:

jistabout wrote:The controller is a PC with custom one-off software and has also been running trouble free for many years.

I'd like to hear more about this...

I promised to tell more about computer control of the repeater when I had time so here goes .

The computer is interfaced to the radios via J4 on the R.I.C.K., to a serial port on the computer. A simple bi-directional level converter consisting of 2 NPN switching type transistors (I used 2N2222s) converts RS232 levels to TTL levels for the GR300. At the com port on the computer, the CTS line is used to sense COS activity from the receiver, and the DTR line is used to key the transmitter.

Repeat audio is routed through the computer's sound card - RX audio to line in, TX audio to line out. Under program control, the sound card mutes/unmutes audio as needed.

The control program can be written in any programming language which can access the com ports & sound card. My program is written in MS Visual Basic 6.

Software timers within the program control all timing - carrier hang time, courtesy tone if used, and transmitter time-out among others. The program doesn't require very much computing horsepower. It will run quite reliably on an old 266mhz 1st generation Pentium.

That's a basic explanation of whats going on with it. Using a computer for repeater control opens up a whole different level of possibilities vs. using a hardware controller. Features can be easily added and/or updated simply by writing them into the software. As an example, I just recently completed writing into the program a simple IP server which allows me to command the repeater with my smartphone, thereby satisfying the FCC repeater control requirements for amateur radio repeaters. All aspects of repeater operation are easily changed via a simple user interface.

In my case, the old Mitrek repeater here has been running under PC control for 9 years without any problems whatsoever, and it look so far as if the GR300 will be reliable also.

As a historical note, I was actually experimenting with this back in the early 1980s.....Myself and a friend wrote one of the very first repeater control programs and ran it on a Commodore VIC-20. That computer was connected to a Motorola 80D repeater station, complete with "Sensicon A" receiver, and 829B PA tube in the transmitter. Copies of that simple program are still floating around to this day .

Hope this helps, any questions please let me know.


- Darrell/K7LZR