Horn Diaphragm

RonD2 · Post by **RonD2** » Mon Dec 07, 2020 5:24 pm

I know this is a long shot but thought I'd ask if anybody has a bad horn in their scrap or salvage pile (without much corrosion) that they'd part out the diaphragm for a fair price? Mine is shot (full of holes).....

This is out of an Autolite Electric HX-4004-UT 24vdc horn. From what I can tell, M-series Autolite and Sparton diaphragms are all the same. Haven't had any luck finding NOS or repop diaphragms. If I could find out who has the current military supply contract to make 24vdc horns I'd call them. Believe it or not, except for this, the rest of my horn is in good shape.

Thanks!

Eades · Post by **Eades** » Tue Dec 08, 2020 11:16 am

There is a guy on eBay right now with $25 Spartan horns. Good luck.

RonD2 · Post by **RonD2** » Tue Dec 08, 2020 11:24 am

Thanks Rick! That's my fall back plan.

RonD2 · Post by **RonD2** » Mon Dec 21, 2020 6:47 pm

Taking a chance that they're all the same, I got lucky and was able to locate a replacement diaphragm from a similar (but not the same model) take-off horn. The donor horn had no tag so I can't tell the maker, but it has the "dog dish" style back and different internals than my "dome" style Autolite. But the diaphragms are near enough identical to be the same. Got to clean this one up a bit more and paint it, but it's solid.

45auto · Post by **45auto** » Mon Dec 21, 2020 8:42 pm

Outstanding!!

RonD2 · Post by **RonD2** » Tue Dec 22, 2020 10:03 am

Thanks Harold !
I've still got to finish cleaning up and re-wiring the HX-4004-UT horn, then reassemble it and properly adjust the switch contact points for that sweet sound.

Hopefully I'll still have a good working horn when I'm done. I'll take and post a few more photos of that in another thread shortly.

4x4M38 · Post by **4x4M38** » Wed Dec 23, 2020 7:20 am

Ron,
Just a thought. You may not want to paint the diaphragm. It’s internal anyway, but doing so may dampen the sound.

Just my two cents.

Brian

RonD2 · Post by **RonD2** » Wed Dec 23, 2020 12:09 pm

Hey Brian,
Yes, considering that. On inspection of the original and donor diaphragms, only the top outboard side is painted (I'm guessing) because it can be seen under the outer grill and shield, or just got painted incidental over-spray, can't tell which. The undersides are bare metal. I'm kind of concerned about corrosion long-term (even though it'll likely never get wet), so I might either give the underside a light coat of primer or clear anyway. If I can't adjust the horn for sweet sound I can always strip it off. Thanks!