My first job out of college was with E-Tron, a now defunct military contract manufacturer. The company was desperate to get someone in, because the guy I was replacing was moving in a matter of days. Thus, after I graduated from DeVry on that Thursday, I interviewed with E-Tron on that Friday, and starting working on that Monday. I was hired as an Environmental Test Engineer. I received a day-and-a-half of training, and was told I needed to perform a complete set of shock, vibration and temperature tests in accordance with MIL-STD-810 on a device called a blasting machine. In addition, I needed to prepare and submit a detailed test report to the Government inspector the following week. No products could be shipped until the report was approved by the Government inspector and the general contractor - General Dynamics. Talk about pressure. This was asking a lot of a guy who less than a week ago was a short-order cook! But I was up for the challenge.

This is a photo of a pneumatic shock test machine with the carriage in the armed position. You can see the lead pellets right below the carriage, along with the trigger mechanism. The resulting sawtooth waveform is shown on the right.

Many companies still employ this type of test machine, even though studies have shown the shock pulses produced are not representative of real-world conditions. My good friend Wayne Tustin , a true pioneer in dynamic testing, can a test to this fact.

Here is a link to a good article co-authored by Wayne that details the limitations of classical shock waveform testing.

In addition to shock testing, I also performed vibration testing on a benchtop vibration shaker. It was one of the smallest electrodynamic shakers I've ever seen, and the slip table was merely a granite block. I used the setup to perform swept sine vibration testing on the blasting machine. The vibration control equipment was manufacturer by Trig-Tek. I have since used Trig-Tek equipment in almost all of my vibration testing projects, and I have always found them to be an excellent source for quality, low-cost instrumentation.

Example of a vibration shaker with granite sliptable.

High and low temperature testing was performed in a Tenney Engineering chamber. Back then, the chambers were still blue and had rotary temperature controllers mounted on the outside. You could lose hours of recorded data by forgetting to start the chart recorder (yes, it happened). Charts were a valuable part of test reports, and often required repeating entire tests when data was missing. Today, Tenney is owned by a company called TPS. I can't comment on the quality of the new chambers, since I converted to Thermotron many years back. Both companies now produce beige chambers, which I can't say I like very much. They just don't have that nostalgic look and feel of old. However, you still can buy the blue ones-- as an option.

Functional testing of the blasting machine was performed before, during, and after exposure to each test environment. Since the blasting machine pneumatic tester was located on the manufacturing floor, I would have to put on large oven mitts and quickly transport the unit to the station. The functional station used pneumatic control to turn the handle of the blasting machine, which generated an output voltage across a passive load. The waveform was captured on a Nicolet digital oscilloscope. A chart recorder was connected to the scope for plotting the waveform.

When the test chamber was idle, you could often times find food and drink inside. The technicians used the chamber as both a refrigerator and warming oven, for lunch and leftovers.

Me and Kwon troubleshooting a problem with the ATE.

The ATE system employed a Hewlett-Packard 300 Series computer, Crown Amplifier, HP 3488A Switch Control Unit, HP 3456A DMM, HP 3325A Signal Generator and Daedal Rotary Table & Controller. The control language was HP-BASIC (Rocky Mountain BASIC), which I taught myself over a period of weeks. (Click here for some background information on the migration of BASIC over the years). All instruments were GPIB controllable, but GUIs were still in their infancy. The best that I could do at the time was program the function keys on the computer monitor, which allowed the operator to perform specific tasks.

A Rotary Variable Differential Transformer (RVDT) is an electromechanical transducer that provides an AC analog output that is proportional to the displacement of a separate movable magnetic core. It usually consists of a primary coil and two secondary coils symmetrically spaced on a rotary form. The differential output of the two connected secondary coils is linearly proportional to the displacement of the movable core.

General Dynamics used the RVDT for two applications on the M1A1 - steering and throttle control. Unlike a standard drive-train vehicle, the tank needs to send signals back to the engine control using electrical signals. One RVDT was placed in the steering assembly to navigate the tank. The other placed in the right handle, used like a motorcycle throttle.

Looking back, it was amazing how we communicated without the use of personal computers, e-mail or cell phones. We had one word processor in the engineering department, which only the company secretary had access. Here I am printing out a test report on a dot matrix printer, while Paul (mechanical designer) works on a fixture design. See that old relic in the lefthand corner? - that was called a typewriter!

E-Tron provided a good basis for my career. When I first started, I was chief cook and bottle washer. After a year, we hired two technicians to assist me in the growing number of contracts. I found it easier to lead others when you have actually done the work yourself. Below are pictures of Bob Leticeq performing RVDT tests on the ATE system, which was also my office.

For a small company of only 50 people, E-Tron managed to secure several large military contracts. Unfortunately, the company failed miserably in their execution. The problem was quality control. During the brief two years I was there, I saw three different QA managers. The Government issues warnings, then withholds payment when quality becomes a concern.

I recall the company being awarded three major contracts for radar chaff production. At the time, Tracor (North Carolina) was the only qualified producer of chaff in the U.S. Even with three continuous shifts running 24 hours a day, Tracor couldn't keep up with the demand for chaff from the Army, Navy and Air Force. Chaff was used for training, as well as, actually military missions. E-Tron received an initial $3 million contract to produce chaff packages about the size of a pack of cigarettes. This small form factor was excellent for storage and transport, but meant large bundles were needed for each application. The Navy alone fired several thousand packets during each training mission.

E-Tron was unwilling to invest in the precision cutting and packaging equipment necessary to produce chaff in bulk quantities. Instead, they decided to employ a series of razor sharp blades (the poor engineer that worked on this equipment was always covered in bandages) along a conveyor belt line that would essentially reduce a roll of aluminum into a pile of fine aluminum strands. Unfortunately, the daily fluctuations in temperature and humidity caused the alignment of the blades to drift each day. The length and width of the chaff strips were critical, because each chaff package was designed to confuse a specific enemy radar. It soon became an exercise in futility trying to calibrate the equipment prior to each production run.

I was responsible for environmentally testing the chaff dispensors, which had to fire reliably under hostile operating conditions (high/low temperature, altitude, humidity, salt fog, shock and vibration). This required most testing to be performed at an independent testing lab. I was able to convince the Government Defense Contract Administrative Service (DCAS) inspectors to allow me to use "dummy" chaff packages. It would have been a nightmare trying to contain an actual chaff cloud in a lab environment.

Rapid Bloom Chaff (RBC) creates a "cloud" to decoy a missile (Courtesy aerospaceweb.org)

Radar chaff is a passive electronic countermeasure in the form of metal strips that are ejected either from an aircraft, ship or rocket. Chaff is ejected from an aircraft, much like a flare, and it creates a cloud of material that looks like a big radar target to an RF missile. The missile either goes after the larger target, or the target can be obscured by the cloud of chaff.(see figure) Chaff was first used during World War II when the Royal Air Force, under the code name "Window," dropped bales of metallic foil during a night bombing raid in July 1943. The bales of foil were thrown from each bomber as it approached the target. The disruption of German AAA fire control and ground control intercept (GCI) radars rendered these systems almost totally ineffective. Based on this early success, chaff employment became a standard bomber tactic for the rest of the war. Click here to read a 1846 Electronics article on radar chaff, which still contains some good information.

As E-Tron's quality problems continued to mount, and the Government became reluctant to give the company any new contracts, I soon realized the end was near. So, I started searching for a new job, which I eventually found with H.F. Henderson Industries. E-Tron went out of business in 1988.