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Notes
- I (Ed Thelen) was on an Ajax site 4/55-1/57
- A.J.M.Weijenberg was on a Hercules site 1/69-6/72Table of Contents
- (Vacuum) Tube Tester
- Volt Ohm Meter
- Synchro Scope
- Wheatstone Bridge
- more ;-)) Dec 29, 2014
We in the IFC had a tube tester similar to this (A.J.M.Weijenberg thinks there was no tube tester in the launcher area. )
A.J.M. (Jos) Weijenberg sent these pictures to remind me of "the good old days" ;-))
Tube Shop
Also often in a drug store
Tube Tester
Near by was a multipage chart showing switch setting for each of several hundred tube types it could testWhen part of a system didn't work, and the interlock switches were either correct or cheated, a good plan was to try to locate the failing circuit by dividing the signal chain in half, then in half again, ... using various operational tests, switches, oscilloscope, ... whatever it took.
When a circuit in a chassis didn't work correctly, (and all the filaments were lit ;-) a person had several options.
- (We did not have spare chassis to swap)
- In general we had spare tubes. Then "Easter Egg" it - swap tubes until the circuit worked or determined the fault was not a tube
- If the tubes seemed good, maybe a "passive" component (resistor, capacitor, diode, rarely a transformer) was at fault. If it wasn't something obvious - broken wire, smoked resistor, ... then you needed a scope and circuit knowledge. Fortunately, our training was very complete, and we were young with retentive memories :-))
- We were not equiped with many passive components - the chassis could go back to Ordnance for swap and repair. Fortunately this was very rare - other than the lump in the TTR elevation potentiomenter which we discovered, I think the only chassis we had to swap out (down time) was due to smoked resistors in the pulse code generator in the MTR.
We had a good rugged analog meter similar to this. (Digital meters for field use were not available yet.) It was in a leather case and could stand up to normal field use.
We also had an oscilloscope which was a ruggedized simplified version of the nice Tektronix oscilloscopes we had in the school labs. The sync circuit for the sweep was simply a coax to the 1000 Hz ( 400 Hz in the Hercules) "clock" that drove the magnetrons and most of the display scopes in the IFC. Although it did its intended job well, I really disliked it 'cause you couldn't play with it, like display voice wave forms because the sweep trigger circuit was so primitive :-(( If you look up "Synchroscope" now, you will find a display used to help synchronize two AC generators - not our equipment at all.
Wheatstone bridge from Wikipedia. Ours was a brief case size instrument in a polished plastic case, intended for gentle handling. Before moving it you wanted to slide a little "button" to clamp the sensitive galvanometer movement so that the little pivots or fine wires wouldn't break.
This Wheatstone Bridge was used to check voltages under test condition in the analog computer.
Dave Lion has a Wheatstone Bridge with an external galvanometer here. Wikipedia mentions galvanometers with 100 micro amps full scale, ours had about 20 divisions so possibly we had 5 microamps per division. And of course you could balance to well under one division, lets say one tenth of a division.
more ;-))
from A.J.M.Weijenberg, Dec 29, 2014