ESI cables for bridge system

Today we got an interesting set of cables, designed by ESI for their bridge systems such as 242D in the late 1960s or early 1970s.

Cable looks like typical Belden with nice insulation and moderate flexibility. Connector jacks are huge aluminum cases with gold-plated over nickel banana terminals. Photos show conditions as received, forgive the decades long crust and dirt present.

Welcome stackable banana interfacing cables. ESI 9346 is just a short banana with stacking port on the other end. It can be used to tie multiple terminals together on same node with low contact resistance and full shielded metalwork around the signal connection.

Center banana pin held on acrylic or polycarbonate insulator. It would be very interesting to test leakage of these insulators and see if these can be used for very high resistance measurements, such as above 100 MΩ.

The machine work is very good and everything feels very robust and designed for hundreds of cycles with operator manual work, as was typical for manual ratiometric measurement systems back in those years.

These stackable ESI banana connector pretty cool and feel real solid when connected together. Little steel spring ring holds the aluminum plug snug and firm together in the connector stack.

Sadly gold-plating is done over the thick nickel underlayer, so it’s not low thermal EMF.

ESI 9347 is short dual banana connector into dual banana connector plugs. ESI 9345 is same style but single-banana type variant.

ESI 9277 is dual banana plug connector into kelvin gold-plated alligator clip jaws. Rubber got destroyed and solidify after decades in storage, but should be easy enough to fix.

ESI 9332 cable is dual banana plug into single non-stackable banana plug.

ESI 9294 cable is single stackable banana plug into non-stackable short banana plug.

ESI 9337 cable is single non-stackable banana plug into same type plug.

ESI 9335 cable is short dual banana plug into dual banana plug.

ESI 9330 cable feature dual banana plug into dual kelvin connected fork with shield terminal.

ESI 9331 cable feature single banana plug into dual kelvin-connected fork with shield terminal.

This 5-plug header with two cables designed to plug into bridge interface and provide two kelvin-connected gold-plated clips for clamping on the terminals or wires. Rubber that gives spring return action to the clip jaws turned into solid plastic goo from the age, but this can be easily fixed up.

And here’s the cable example plugged into ESI 240C bridge out of ESI 242D system.

Perhaps we can try these cables on the full system for historical reasons some day…

Stay tuned and let us know your feedback on this post! Discussion about this and related stuff is also welcome in comment section or at our own IRC chat server: (port six-zero-ten-zero, channel: or via e-mail.

Author: Ilya Tsemenko
Created: Feb. 20, 2024, 4:18 a.m.
Modified: Feb. 20, 2024, 4:19 a.m.