GE MVS IRLP Wiring Instructions

(This text, and instructions for connecting other radios for IRLP can be found on the IRLP website at www.irlp.net/pnp-radio-pinouts.html.)

The option connector is found by removing the metal plate from the bottom of the radio. Two Torx screws hold the plate on. With the plate removed, locate the 13 pin option connector, near where the power cord enters the radio. Pin #1 is closest to the back of the radio.Note that the GE-MVS manual refers to pin #10 on the MVS as an audio mute pin. However this pin generates 5 volts DC when a signal is detected, making it useful as a COS pin.

Ground DB9 pin 6, and audio jack ground to one of the screws near the option connector. Ensure that the radio and your computer share a ground.

From the point of view of the MVS Option Connector, the connections are as follows:

Audio Levels

This method of connecting your radio is simple, but you may find that the audio level from the radio is low. Before doing anything, check the volume setting on your radio. On at least some MVS radios (apparently not all), changing the volume will change the output level on pin #3. Travis, AA9NV, reported to me the following: "I fought with audio for three days assuming pin # 3 audio was wide open audio and thinking something was messed up with the tnc or such when all I had to do was turn up the volume. I connected the MVS to my HP service monitor and sure enough, the audio goes from very weak to multiple volts by the time it hits the half way mark connected only to pin # 3, no other audio was connected." If this is the case with your radio, set the volume level where you want it for proper audio levels into the computer, and leave it.

I have found this on some GE-MVS radios but not all, and have yet to correlate this effect to certain model numbers. (Travis' model number was NPH20.) If changing your volume level has no effect, and your audio is too low, to boost your audio output, follow one of the two suggestions described in the "Improved Interface for GE Phoenix RX audio" section on the IRLP website. If you are going to take audio off the speaker (the simplest approach) the following photo locates the speaker connection.

Follow the board where the option connector is located toward the front of the radio. Remove the ribbon cable temporarily. Toward the front of the radio is an orange two wire cable. This is the speaker cable. To tie in directly to the speaker, connect to the pin closest to the transistor (in the photo, a blue wire has been soldered to the pin.) If you're not sure which pin to use, get out your ohm meter. With no power to the radio, measure each pin against ground. One pin will show 0 resistance against ground. Use the other pin.

If you connect to the speaker pins, and reconnect the speaker, you will bleed much of the signal off to the much lower resitance of the speaker. You will have to run the volume quite high to drive your sound card properly. On the other hand, if you keep the speaker wires disconnected, a very low volume level will provide ample signal level. (There is no point in leaving the speaker on, as you can only hear one half {the RX} of any IRLP conversation anyway.) If, without the speaker connected, you are overdriving the input of the sound card, try soldering a small (under 100 ohms) resistor across the two pins. That will bleed off some of the signal as the speaker does.

Visit www.irlp.net/pnp-radio-pinouts.html for information on connecting this and other radios for IRLP use.