What is This?

Here's a wild a$$ guess.

It's some kind of thermal switch and 373C is the Curie point of the magnetic strips, the temperature above which they lose their magnetic properties. (Pure nickel Curie point is 358C, maybe its an alloy of nickel/iron)

Interesting thought! We had thought of a magnetic switch, but had not thought of the Curie temperature. The curie temperature of nickel is 627K, or 354°C, so with just a bit of iron alloyed in, 373°C sounds quite attainable.

ON the other hand, as I indicated in the original post, the brass tube inside the body appears to be continuous from one end to the other. I measure 0.1Ω resistance from the contact ring to the collet, with the long strip completely removed.

Perhaps this could be the core of a coil, part of a resonant circuit that would suddenly move into or out of resonance as it passed the Curie temperature...

On the third hand, 373°C sounds a little high for phenolic, even though 50 or 60 years ago, I believe phenolic was the best economical plastic available for higher temperatures. Teflon™ was new and very expensive.

Ha! I just noticed that you already had a Curie point temperature for nickel in your post. I didn't see it when I first read it. Fortunately, our sources agree within a few degrees... And we both independently thought of alloying in a bit of iron.

I did look up the temperature limits for Bakelight, the earliest phenolic and quite likely what this is made of, and it's only 90°C for continuous exposure, 105° for brief exposure. So I'm virtually certain that the 373C must have some other significance.

Tool for checking the polarity of an antenna.....

http://www.l-com.com/blog/post/2017/03/16/All-about-Antenna-Polarity.aspx

Please elaborate! I do understand antenna polarities, but don't see a connection to this device.

No clue, just a wag....

Rather than an antennae testing tool maybe it is a removable antenna itself.

Can you pull out the brass tube? Does it extend?

"Can you pull out the brass tube?" No. The phenolic tube has about 0.025" wall thickness, and clearly has a couple of bulges where rings of the brass tube have been pressed in to it. Here's a photo that shows the bulges, if you look closely, about half an inch in from the body end..

Also in this photo, you can see the brass collet and a section of the long strip, with a rounded end. While taking this photo, I noticed that the last 1/4 inch of the strip is tapered (both ends), so the very tip is only about 0.010" thick. Also, now that I looked more closely, I'm not at all sure that the discoloration on the end of that strip is pitting. It may be a deposit of some kind. I was able to remove some of it with my fingernail. I have the impression that if it is rust, it is from contact with some other object.

Here's a photo of the other end, removed from the tube, but with the strip having the bend inserted:

As you can see there are perpendicular slits cut into the phenolic to hold the strip. The two slits have different gap thicknesses. One slit holds the strip tightly, while the strip fits loosely into the other slit. This assembly snaps into the non-threaded end of the brass, and can be rotated to any position after insertion.

Seeing this shows me that the end of the short strip with the bend has to be toward the center of the body.

If the long strip is inserted when the short one with the bend is already in place, the long one hits the short one with about 1.5" still extended. Only a little wiggling makes the long one easily pass the bent one and slide the rest of the way in.

These pics make it look like an Exacto knife with a rounded chisel blade. Possibly blade storage in the handle section? See the collet on this Exacto brand knife.

I tried looking up "hobby knife" on Google and found one that's vaguely similar made by Tamiya. Wasn't able to find an exact match nor was I able to find a rounded blade like that.

The collet is indeed very much like that of an Exacto™ knife, but there are no sharp edges. the thinnest tip is still 0.010" thick. I haven't tried filing it, but I don't think this material is very hard.

Still, thanks for the thought! All ideas are welcome, unless/until someone can come up with a definitive answer.

BINGO! Thanks a lot! How'd you find it?

Mostly luck, I think. After deciding that C didn't mean Centigrade, I decided it had to be some kind of tool with the part number 373C that fit in a narrow gap.

Many, many years ago as a field engineer, I had to work on a telephone crossbar switch and there was a special tool to clean relay contacts without damaging the gold plated coating. I guess maybe that was in the back of my mind.

Nice find!

Good one! It's a burnishing tool holder 373C. The inside blade is the burnishing tool 374 A (B or C). These are from the old Bell Telephone Company (AT&T).

Great observation! The blade (burnishing tool) would fit in the slots, just like the knife you copied.

I recall a mechanical pencil that had a collet like that. Is anything spring loaded. If I remember correctly the pencil I am talking about was spring loaded. Push one end and the collet loosens up on the other end to slide the lead in or out.

I thought I was going to include a photo of one of those, but I didn't find it... I know I still have one somewhere. I thought it might be with my collection of slide rules, drafting templates, and French curves, but it wasn't there.

There are no springs in the unknown device.

I'd send these photos to the ARRL. I'd bet some member would know.

www.arrl.org/home

Interesting thought. although I'm not yet fully convinced that it's a radio device.

Part of a military radio antenna.

The blade is part no 374A, 374B and 374C.

The 'burnishing tool' suggestion is indeed correct. While still in college I worked over one summer for Illinois Bell preparing a central office for cut-over from #5 crossbar to ESS. These tools were all over the #5 crossbar area of the building.

My favorite memories from this job were when I was working the night shift. At 2:00 in the morning the sounds from the relays were infrequent, a click-click here, a clack-clack there. As our community awoke and began their day, the office crescendoed. By 8:00, the din from the relays was so loud and continuous, conversation in the crossbar aisles was difficult without raising one's voice. Hearing the village come to life each morning was rather magical. I suspect today's central offices sound pretty much the same any time of the day or night.

Thanks. I see in Rixter's link, that the drawing is dated 1976. Is that generally the time frame of your experience?

We really appreciate all the replies to this thread. Curiosity was intense...

Quite a coincidence. Yes, it was in fact the summer of 1976 in Wheaton, Il. I graduated high school (Glenbard West in Glen Ellyn) in '75.

Let me guess. Uhmm...it's hard on 373 deg C only. Otherwise, it's sag.

That's it guys, I am out of here. Just dropping by to say hello to yah all. It's good you're all doing fine.