Need help splicing u-94/u ptt with u-174/u military plug.

[MotormanLocked]

New user. I'm not an electrian or an avionics tech. I'm trying to splice together a u-94/u M9177/5-2 tjs-102 ptt switch with u-174/u M9177/2-1 tp-101 military plug. For use with a military headset. All military; I'm not trying to convert anything to civilian. This is all aviation gear that I'm setting up for ground use with military portable radios that accept 174 plugs.

I have an issue David Clark (H10-76 I think) headset plugged into the ptt. For testing I have a two wire external speaker, a battery power source, and a simple light bulb current tester. Started with 9 volt battery and switched to a 12 volt car battery. With these batts my test gear squawks and lights up but I think army helicopters run on 24 volts with some systems on AC and some on DC; I don't know if that matters. I have tried various combinations and I can produce squelch in the headset and external speaker as well combos that verify the ptt breaks squelch but I'm not sure if any given wiring combo is correct. I have not been able to produce any sound through the microphone; if its even possible with test set-up I have. I don't know if I need AC or DC. I'm obviously lost and have no clue.

Can anyone provide a simple color to color wiring solution? The ptt leads are red, black, green, white, and the yellow jumper for the switch; one for each color wire. The 174 plug leads are: 2x White, 2x Black, 1 red, and 1 green. If someone could just tell me which wires go to which wires that would be amazing.

 

[romanr]

If you need to connect a headset onto the audio panel of a military helicopter, you should have the crew chief get an avionics guy to do this.
No offense intended, but your questions make it clear that this task is beyond your skill level.

 

[MotormanLocked]

If you need to connect a headset onto the audio panel of a military helicopter, you should have the crew chief get an avionics guy to do this.
No offense intended, but your questions make it clear that this task is beyond your skill level.

Thanks for the reply. As I said, this is for ground use only. Not aviation ground support. Infantry type ground use to be used with portable, handheld radios.

In a previous life, I had sets of gear with aviation components. Ballistic helmet outfitted with aviator night vision mount and battery pack. We used to use aviation goggles. Aviation headset worn under Gentex SOHAH ballistic helmet designed to be worn with "over the head" comm sets. Plugged into a U94 ptt switch that plugged into my handheld radio which was molle mounted on my body armor. We used this equipment for cross compatibilty and convenient access for tech/maintenance support services. Plus the 174 plug is in widespread use. If a given piece of comm gear didn't accept the 174 plug, we were issued adaptors.

It's just a switch. The mechanics I can handle. I can make very solid splice connections using pin sleeve connectors and I can solder. Red to red, green to green etc.; no problem, I can make a splice as strong and durable as an electrician. I just don't know what to do with this friggin' yellow jumper that would complete the circuit to the switch. I don't currently have a crew chief, avionics tech, or a helicopter at my disposal. I need this as a back up for some contractor work coming up and I'm not going to have enough time to hunt down someone who can do it. Thanks anyway.

 

[speedway_navigator]

Does the portable need to see voltage for PTT? All the commercial radios I've worked keyed when the PTT lead went to ground.
When I was in racing I'd get people bring in aviation David Clarks wanting to know why they didn't work on a Standard or Motorola radio.
Most radios use 150 ohm mics and 8-16 ohm speakers, the aviation models were 5 ohm mics and 150 ohm speakers, I think 300 ohms wired in parallel, but it's been a while.

Some radios used balanced audio so they needed an audio xfmr so the speakers could use a common ground. We used
1 ground
2 PTT
3 mic
4 spkr for race car harnesses and portable to headset wiring.

You should be able to verify the resistance values on the nexus plug.

And don't make the mistake I made at a race one night when I had a new driver's helmet with no tx audio. I ohmed out the nexus plug and had nothing between pins 1 and 3, so I replaced the M101 mic. I still had no reading and spent a few minutes flexing the mic lead to make sure I didn't have an intermittent open.

Finally I got smart and ohmed out each pin from the solder side to the plug side of the nexus and found pin 3 was open.
Since it was a new helmet kit I KNEW the plug was OK....

Never assume nothing is poor grammar but sticks in your mind as a troubleshooting tool.

 

[mancow]

1st please don't put car batteries on anything, the current could roast the hell out of everything. Yes some aircraft use 400 Hz AC for primary power.

Can you post some more details about exactly what equipment you are trying to interface?

 

[romanr]

The typical "infantry type" portable today will probably have a connector for an H-250/U handset. The 5-pin version of this is the U-229/U on the handset, but there is also a 6-pin variant, the U-329/U.

There are some Motorola portables radios such as the SRX-2200 around that use the Motorola APX connector - please let us know if the SRX-2200 *is* the target radio.

The H-250/U and it's various replacements have a microphone impedance of 150 ohms and a speaker/headphone impedance of 1000 ohms. The 1000-ohm speaker can be matched to 8-16 ohm circuits pretty easily with a transformer, but matching a 150-ohm dynamic microphone to a system with a different impedance will require a better understanding of the target system.

You can find the pin out of these connectors here:

U-229 Connector pinout

cryptomuseum.com

 

[prcguy]

Sounds like the OP is only making an interface with PTT between a male and female Nexus connector. If the headset is otherwise compatible with the radio equipment it should be a simple wiring job, which I don't have the answer for at the moment. If he is trying to interface the DC H10-76 headset to something other than an aircraft radio the 5 ohm impedance of that mic will be a problem. Some non aircraft radios use a higher impedance dynamic mic and others use condenser or carbon equivalent mics which need a bias voltage and they would not be compatible without an appropriate interface box with power source and preamp.