Simplex Repeater
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As you can tell, I'm into NHRC repeater controllers.  Here's another project I've done with an NHRC-2.   This has been on the air over 3 years without a problem.  After a request, I dug up the 1997 e-mail where I described the project.   I'll try to take some pictures of the project soon.

Directions to connect the NHRC-2 Controller to a GE Phoenix mobile.

“Did he say a Phoenix? Doesn’t he mean two? Those radios can’t do duplex.”

Yes, I did mean one Phoenix. But you’re right, this isn’t a duplex radio or a duplex repeater How? Well, with the NHRC-2 controller. 

In addition to being a neat low cost duplex controller, it has a simplex mode. In this mode, it will store 20 seconds of audio and play it back when the user unkeys. Perfect for a temporary repeater. It also does a CW ID to keep you legal. You can remotely reprogram and control it.

The GE Phoenix is a low end, synthesized mobile radio. Since it’s not rock bound, this can be a quick way to get a radio on the air fast. You WILL need a friend with a programmer. Since the radio can’t be on more than 50% of the time, you shouldn’t need to worry about lowering the power output.

Bill of Materials:

Part Source
11 circuit terminal housing, .156 Digi-Key WM2109-ND 
8 circuit terminal housing, .156 Digi-Key WM2106-ND
Pins for above Digi-Key WM2300-ND
8 conductor cable, 10” Any, shielded would be nice
Hook up wire, about #22 Junk drawer

There is just one very simple mod you need to make inside the radio. You need to being the CAS outside. It’s just a wire, so don’t panic.

In case you don’t have a manual, J910 is the 11 pin connector on the rear. Pin 1 is on the left as you look at FRONT of the radio, right side up. J911 is the other, mostly microphone, 8 PIN connector. Also, Pin 1 is on the left as you look at the front of the radio.

Take off the top of the radio. Look at the top board near the front for a long pin labeled J921. Run a thin wire from here to the hole just behind J910, Pin 5. This is designated as a ‘spare’ lead. A touch of solder on each end and you’re done. Put the cover back on.

This lead goes high when the squelch is open. This is what the controller needs to know to start recording. When the signal goes low, then the controller will key up the radio and retransmit the audio it recorded.

Omit the DB-9 connector on the controller. There’s only a few inches between the controller and the jack you’ll be using on the radio. Thanks to nice engineering on both the radio and the controller, the interfacing is easy. Just solder the wires into holes for the DB-9. As you’re building it, take the de-emphasis options.

I take the controller power from PIN 1, which is usually used for the Ignition. At least in my radio, Pin 1 is jumpered to Pin 11, the high current input lead. If yours isn’t, get power from Pin 11.

DB 9 Connections Signal My Color Code GE Phoenix rear connector
1 Ground Black J910 Pin 7 (GND)
2 13.8 V Red J910 Pin 1
3 PTT Violet J911 Pin 2
4 TX Audio Blue J911 Pin 4
5 RX Audio Orange J910 Pin 4
6 CAS + White J910 Pin 5
7 CAS - Yellow J910 Pin 8 (GND)
8 Ground Green J910 Pin 7 (GND)
9 Ground Brown J910 Pin 7 (GND)
n/c   Shield J910 Pin 7 (GND)

In case you need it, the radio’s deviation control is R320 on the top board, extreme right front corner.

The radio I used to design this hook up is a Phoenix VHF, 16 channel with scan (N5HH1W40PB). Almost all the features go to waste in this application. I would assume a simple version would work too. Let me know if you have one and if it did work as I described.

I do need to bring up something in the rules. Here’s what the FCC calls a ‘repeater:’

97.3 Definitions. 

a. The definitions of terms used in Part 97 are:

37. Repeater. An amateur station that simultaneously retransmits the transmission of another amateur station on a different channel or channels.

This set up will not be simultaneously transmitting. Yes, there’s a up to a 20 second delay. BUT, many of the popular repeater controllers have a time delay to help mute DTMF completely. Think about when these rules were written, cheap time delays didn’t exist. But, please read this for yourself and come up with your own conclusion.

Thanks to the NHRC guys for their work on this controller. This project was fun to build and the engineering that went into it far exceeds the standard ham radio type of project. The web page support makes it an on-going development project. I can’t wait for the next release.


rev 01/14/08

Except for portions owned by others, Copyright: Ray Vaughan, 2008