"Wait...what?" The 1930's Bendix Antenna Terminal

One of the more inexplicable design choices for some of the Bendix equipment was the bright idea of providing a quickly removable antenna terminal. I'm not sure how much of their product line deserved the dubious honor of receiving these terminals, but at least the TA-2* series transmitter, its MT-36 MF tuner, and the MT-66 artificial antenna certainly shared it. Its high probablity for misplacement(i.e., accidental loss) is reflected in the fact that thirty years of trying to find a single example has so far been a failure. Finally overcoming a certain amount of inertia, I decided to try and replicate a reasonable facsimile of this part, cryptically identified as the "AE11089" antenna post.

I started with the fact that the basic quick release mechanism was the Dzus fastener, patented in 1931. Popular for retaining fuselage access panels on aircraft, the engineer assigned the antenna terminal role must have been enamored with the functionality.

Patent for the Dzus fastener.

Below is a glimpse of this elusive terminal from the Bendix TA-2J manual:

Antenna Terminal AE11089

Here is a photo of the interior of a Bendix product with the terminal interface:

Interior view of the Dzus spring that the antenna terminal interfaces

Since I had no dimensions for this terminal, I had to rely on scaling the photos and drawings in the manual. As a result, it may not be a precise duplicate, but it appears to be pretty close.

Piece parts for the assembly

The three parts shown at the upper left above illustrate the breakdown of parts that need to be made. I started with a standard Dzus fastener from Aircraft Spruce, then cut off the screwdriver head and threaded the shaft with a 1/4-28 thread as shown in the finished piece above the standard part. I knurled a long piece of 1/2" stainless steel, then cut off pieces to make the rest of the assembly. It's a straightforward wire terminal, same as a thousand similar designs like it to capture a single wire between the head and body, with a 3/8"-24 thread to clamp the antenna wire.

Finished antenna terminal

The finished terminal, plugged into the MT-66 artificial antenna, is shown below. You do have to do some test fitting of the depth of the Dzus fastener to make it "snap" into the wire spring without being too loose or being too tight. Not a bad afternoon's work for the three I needed.

Antenna terminal plugged into a socket

I now await with trepidation the almost certain "misplacement" of this terminal in the chaos of the "Flight Deck", after removing it to connect an antenna...

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