Interphone Patch Cord

[Guest cam130nav]

I've got all of the materials to make a interphone patch cord and was wondering if anyone out there has a wiring diagram to put one together. If so, can you e-mail me a copy?

[Guest psfpilot]

Recipe for patch cord:

A patch cord basically pipes your choice of audio into the interphone system through the wires that normally are attached to the microphone. A Good Patch Cord incorporates a resistor into the microphone/audio-in gound wire, because military systems are engineered to use a lower resistance input than the output of a typical iPod/CD player/DVD player is engineered to use.

Cut an old pair of earphones so you now have a wire with a stereo plug. Go to life support and get a helmet cord (our SQ discards the ones that come with new helmets, those are nice). Starting from the tip of the stereo plug, the first two contact bands are left and right stereo channels, with the third band runs to the common (shared) ground wire. Solder a 10k Ohm resistor ($.99 for 5 @ Radio Shack) to the ground wire, then solder the other end of the resistor to the green wire on the helmet plug, which runs to the 1st band on the helmet plug. Then solder L&R stereo wires to the red wire, which runs to the 3rd band on the plug.

Now, take a multimeter and verify that you have nearly zero resistance (Ohms) between the stereo plug's 1st/2nd band and the helmet plug's 3rd band. Verify approximately 10k Ohms resistance between the stereo plug's 3rd band and the helmet plug's 1st band.

For further clarity, albeit with different wire color combos see: https://www.davidclark.com/PDFfiles/H10-76.pdf (right click and "save as" to desktop)

Your helmet plug may have different wire colors, just use a multimeter to verify which wires run to the 1st and 3rd helmet plug contact bands- that is the main thing. When the multimeter reads ~zero resistance, you have found the winning combo that allows current to flow.

Heat shrink tubing is nice to cover up the exposed wires. The proper resistance level may vary according to MWS, (5k to 10k Ohms works on Hercs) so beware that this advice is worth the price you paid. Make sure you heat your work, not the solder: don't just dribble it onto the wires; heat the wires and melt the solder into the hot wires. WEAR EYE PROTECTION IN CASE A RESISTOR BLOWS UP while you are working on it. Work in a well-ventilated area...be smart...etc, etc.

I'll try to respond to messages with ??s.

[ 11. February 2005, 08:22: Message edited by: propdriver ]

[Hacker]

It's much easier to just put earbud earphones on under your helmet. Koss makes a pair of earbuds that have foam cylinders that block outside noise just like the EAR yellow foamies do.

Not only does it eliminate the possibility that when you key the mic, you'll transmit Jimmy Buffett for *everyone* on freq to listen to (heard numerous times in the CAP during NOBLE EAGLE!), but if you're on a crew airplane you won't have to make the entire airplane listen to your tunes.

I have a patch cord as was described above, but I use it to pipe radio and intercomm into my DV camera versus putting music into the intercomm.

[Guest manumsn]

Propdriver,

Thanks for the information. The information that I had was from:

https://www.astrocom-electronics.com/cat_he...et_10299_zw.htm

I thought that I had to have an impedance matching transformer.

I just want to make sure that I don't damage any equipment and that I get (pretty) good sound quality.

Thanks again for the info...

[Guest rumblefish_2]

Hacker,

So does the stereo plug go from your helmet into an AV input on your camera or something? That sounds pretty genius. When did you start flying with the music in your helmet? Is that pretty accepted across the fighter world?

[Hacker]

Originally posted by rumblefish_2:

So does the stereo plug go from your helmet into an AV input on your camera or something?

Yes...depending on how the patch cord is wired, you can either hear just intercomm or intercomm and radio. It plugs directly into the "mic" plug in the camera, a 1/4" jack.

Originally posted by rumblefish_2:

When did you start flying with the music in your helmet? Is that pretty accepted across the fighter world?

This isn't something you do every day, mind you. I certainly don't do it on the 0.7s and 0.8s I'm flying in the Smurf, but on pond crossings, ONE sorties, deployments to Nellis, and other long boring flights that I did in the Eagle, it was a nice thing to have.

[Flare]

Originally posted by Hacker:

It's much easier to just put earbud earphones on under your helmet. Koss makes a pair of earbuds that have foam cylinders that block outside noise just like the EAR yellow foamies do.

Thread revival!

Hacker, is this what you're talking about?

https://reviews.cnet.com/Koss_The_Plug/4505...30235828-2.html

Also, does anyone know where you can just buy one of those patch cords yet?

[ 02. December 2005, 22:45: Message edited by: ENJJPT IP ]

[HerkDerka]

I suggest the Herkbox off of E-bay. It has audio in and out plugs so you can record comm.

HD

[Hacker]

Originally posted by ENJJPT IP:

is this what you're talking about?

https://reviews.cnet.com/Koss_The_Plug/4505...30235828-2.html

Yep...that's them. I still have the same pair I purchased about 4 years ago and they work great. I have abused them quite heavily in that time -- I use them at the gym on the treadmill daily and fly with them occasionaly, and they're still working great.

I have seen other pilots who have performed the following modification, which supposedly is even better at cutting out noise:

https://www.headwize.com/projects/cmoy4_prj.htm

[Guest Hoser]

Originally posted by ENJJPT IP:

Also, does anyone know where you can just buy one of those patch cords yet?

If you take a case of beer down to the comm back shop on the flight line, they are normally good about finding some "spare" parts and whipping a few cords together.

Hoser

[BFM this]

Originally posted by HerkDriver24:

I suggest the Herkbox off of E-bay. It has audio in and out plugs so you can record comm.

HD, do you have one of these? GtG? I looked at it this morning but the auction's been closed out since then.

[HerkDerka]

Yes I have one, and yes they rock. The guy selling them is in my squadron so I can get you in contact if you want. Just PM me.

HD

[Guest HercNav]

I'm the creator of the HercBox, and I'm sorry to inform you all that I'm currently out of HercBoxes. I have the materials to make 20 more and will have them out on eBay, hopefully by Feb 20. If anyone is interested in taking one on backorder, email me at dm_hercnav@hotmail.com. After my projected auction date, you can find them by searching for keyword "HercBox" on eBay. Notice the spelling is a little different than what was mentioned earlier.

[Guest HercNav]

https://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...me=STRK:MESO:IT

This was the LAST HercBox that was sold on eBay.... I think this auction description is what you're looking for. I'm sorry that I ran out, but when I get time, I'll submit more on eBay....

[Guest thebronze]

I sent HercNav a PM about this box working on a "high impedence" aircraft like the C-17.

Does anyone have specifics about HI that they'd like to share, so it can be built/used on Buddha?

[Guest HercNav]

https://www.edmo.com/index.php?module=produ...1237&cat_id=522

I've never seen the comms of a C-17, but would this work? If so, the HercBox might just work on C-17s....

[Guest thebronze]

that wouldn't work, because the plug on the c-17 is a std mil plug, but it's high versus low impedence.

i'm going to try to find out some more info about HI here at Altus.

Anyone else, chime in...

[Guest txaggie_99]

This oughtta do it...JB-23H

Lo to Hi impedance with MIL plug

[Guest thebronze]

GuardAg99,

Thanks, but not really what I'm looking for. Not looking for a more stuff to put on a contraption. Looking for what the difference between HI and LI is, so that HercNav can make a HI box, not add yet another bunch of wires to it.

Thanks though (not being sarcastic, either).

[Guest HercNav]

To tell you the truth, if this JB-23H works as an addition to the HercBox, then it can be permanantly adapted TO the HercBox, thus creating the.... "BuddhaBox?" I'll check out the cost effectiveness and consider adding it to my eBay auctions....

[POKESC17]

I've got the Gremlin as well. On the C-17 it works awsome in the crew position and playing it over the PA. Not so good in the private position but if I'm not using it for the crew then I'm using ear buds anyways.

[Guest HercNav]

If you have an account, keyword search "hercbox" (for example), and click on "save this search." eBay will email you every morning with the search results, so long as there is at least one item where your search criteria is met. With a little patience, you can find some really good deals.

As for my products specifically, use this address:

https://search.ebay.com/_W0QQsassZ130_hercnav

I don't keep many in stock, but at the same time, no listing will be created without one immediately available for shipment.

[devilviper]

Anyone have an in-line plug that would allow me to record off and/or add audio to a mil comm cord? In-line: ie would work with a fighter and not screw up regular comm usage.

Happy to purchase one if someone knows how to build it.

Thanks,

DV

[RangerMateo]

Anyone have an in-line plug that would allow me to record off and/or add audio to a mil comm cord? In-line: ie would work with a fighter and not screw up regular comm usage.

Happy to purchase one if someone knows how to build it.

Thanks,

DV

Any update on this? Anyone have wiring diagrams since there don't seem to be any "for sale" items anymore...looking for something that would ideally be able to both tap the plane audio off to a VOX and playback a signal as well (from an iPod or whatever). At least some good discussion on what the dangers are of tweaking some stuff (ie - don't do this or you'll fry the whole comm system).

[Butters]

Any update on this? Anyone have wiring diagrams since there don't seem to be any "for sale" items anymore...looking for something that would ideally be able to both tap the plane audio off to a VOX and playback a signal as well (from an iPod or whatever). At least some good discussion on what the dangers are of tweaking some stuff (ie - don't do this or you'll fry the whole comm system).

Well, I hate to be the one to quote regs, but.....

From 11-2C-17V3:

5.9. Portable Electronic Devices. IAW AFI 11-202V3.

5.9.1. Do not connect unauthorized equipment (laptop computers, video equipment, food preparation

equipment, radios/tape players, CD players, etc.) to the aircraft intercom, PA, radio systems, or electrical

system.

I just took an old headset apart and connected it to a headphone jack using trial and error. You will not blow the system, unless you are using an amp that goes to 11.