Life before Transistors :-((
(or why the Nike System was so big)

Dear Friends,
A long time ago, maybe a hundred years ago, say 1900, there were no

• radios
• TVs
• Automobiles

I can't tell you about life then, but I can tell you about life in 1950, when the Nike Ajax was designed.
We had

• Radios with vacuum tubes - they weighed 7 pounds and up
  and were usually larger than a loaf of bread or a shoe box.
  If portable, they needed heavy ( 7 pound ) batteries.
• Small (13 inch) black and white TVs
  and up to 6 channels near some big cities
• Automobiles, with self starters :-))
  You did not have to crank to start. Radios were an expensive option.

Nike was designed in that era - World War II was just over. There were no commercial transistors, no color TV, no cell phones, no satellite news, no NASA,
- but the Russians were poking people with their big elbows, had the atomic bomb, and had just helped North Korea invade South Korea.

Since transistors were still a laboratory curiosity, Nike used vacuum tubes when ever you wanted to amplify some signal - and there were lots of signals to be amplified. A guess would place maybe 1,000 vacuum tubes working in the IFC (radar and control) area and maybe 200 working in the Launcher area (including the vacuum tubes in the Nike Ajax missiles.

Why push the vacuum tube point? Because each vacuum tube

• took about 4 watts to heat the electron emitter.
  Your whole WalkMan or MP3 player takes less than 1 watt.
• took about 2 to 4 cubic inches.
  A chip with a million transistors can fit on your finger nail
• took about 200 volts to work correctly.
  Your MP3 player takes 3 volts.
• had an average life of maybe 30,000 hours - a little over 3 years?.
  Every drug store had a "do it yourself" tube tester and had tubes for sale.
  Your WalkMan will last "forever" unless the dog chews it.
• (year 2015) Now we have "smart phones", with GPS, still camera, movie camera, movie player, ...
  and a cell tower based portable phone which fits easily in a pocket.

This meant that the Nike system was

• big and heavy - to hold and power all those vacuum tubes
• maintenance and adjustment of the electro-mechanical parts,
  and the detection/replacement of dead/dying vacuum tubes - was a BIG THING.

A reason modern anti-aircraft systems are smaller, better, easier to transport and maintain is because of - you guessed it - transistors have replaced vacuum tubes in all but very specialized high power, high frequency applications.

The precision analog adjustments necessary to get great Nike accuracy have been replaced by massive digital processing and communicating with the missile and responding to missile sensors. Techniques actually impossible in Nike design days.

A Patriot battery with transistors and modern digital, communication, & radar techniques,

• requires 1/15 the manpower
• is 1/15 the weight
• is MUCH easier to keep working and accurate
• is many times more effective
• and likely much cheaper, not even allowing for inflation.

Dan Lasley found following web sites which give some idea of vacuum tubes

• Introduction to Vacuum Tube Audio Electronics
• Vacuum Tube Preamplifier Analysis and SPICE Simulation

---

If you have comments or suggestions, Send e-mail to Ed Thelen

Return to Home

Updated June 26, 2007