Headset jacks too short?

[Steve Crewdog]

In my contuned quest to find the oddest problem in an airplane build.....

GTR-200/intercom harness built by a reputable avionics company. Installing headset jacks in the panel, 0.063" aluminum with veneer, total 0.100" thick. Washers total 0.021" but when I mount the jack I barely get 1/2 turn on the jack.

The easiest way would be to grind down the back of the panel, but just wanted to see if you had any other ideas, like are there longer jacks available?

Yes, there is a metal washer between the nut and the fiber washer , just not pictured. You can see it on the mic jack.


Thanks,

 

[Pilot135pd]

If that's veneer, and not conducting metal, why do you still have that isolating fiber washer taking up space on the thread?

 

[DMFenster]

Because the fiber washer insulates the inside of the hole too.
BTW - From the picture - I think the washers Stein sells are thinner.

 

[Pilot135pd]

Because the fiber washer insulates the inside of the hole too.
BTW - From the picture - I think the washers Stein sells are thinner.

Then he can remove the rear washer and install that one from behind.

 

[BobTurner]

No, you can’t use a longer jack - the plug would be too short.

 

[cvairwerks]

You can either counterbore the forward side of the aluminum panel to let the jack sit flush on that side and trim the bushing as necessary, or spotface the veneer and panel face deep enough to let the bushing sit below the veneer face.

Personal preference, if there is good access, would be counterbore the panel.

 

[noelf]

Some fiber washers come as a "pair". One is just flat, the other has a raised inner shoulder to center the jack in the mounting hole. Other times, both have the raised shoulder. You only need one of the washers to have the raised shoulder. I say all of this to suggest that you can sand down the thickness of the washers to make them quite thin. This will allow more threads to be exposed to tighten the required nut.

You can also make your own insulating washer out of mylar plastic material. This can be very thin.

And lastly, you can use a large diameter plastic straw (or electrical tape) to go over the threaded barrel of the jack to provide the required insulation that the shoulder washer provided.

 

[Steve Crewdog]

Thanks everyone, all good suggestions, I'm going to let this simmer and think about it.

 

[Steve Crewdog]

Thanks to everyone's ideas, TIL (today I learned):

that you do NOT want the headset jack holes to be 3/8" in diameter and so precise you get metal jack-metal panel contact, instead they should be 7/16", allowing the black washer to isolate the jack away from the panel. Then comes the fiber washer, and voila!, the jacks now fit!

That was actually a nice way to spend a jetlagged day in the hangar. Learned something, cooked a tri-tip on the Traeger, talked to some friends, watched some airplanes, listened to some music, and solved a problem while the wife was at a sewing class all day. I'll sleep good tonight.

(diagram by Dynon, found on the Steinair website.)

 

[PaulvS]

Steve, are you using shielded wire to the jacks? It is hard to tell from the pics.

 

[Steve Crewdog]

Hi Paul,

Now that I've figured out it was my fault I can say that my harness was built by Fasstack, so Yes, it is shielded, and they did a beautiful job.

 

[PaulvS]

Hi Paul,

Now that I've figured out it was my fault I can say that my harness was built by Fasstack, so Yes, it is shielded, and they did a beautiful job.

Hi Steve, that's great. Thanks for posting what was your solution, I've made a mental note for mine, so every lesson is a good lesson!