Electronics > Metrology

GenRad 1403 Standard Air Capacitors

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dzseki:
The other day I was up to my elbows in the company’s e-waste bin, and found these bad guys.

Apparently they are all out of tolerance, measured with a Wayne-Kerr 6505P (1kHz @ 1V):
1pF: 0.997 pF
10pF (#1): 9.97 pF
10pF (#2): 9.96 pF
100pF: 99.86 pF

I have opened up these, in principle they look very simple. Is it possible to adjust these simply by adjusting the plate distance? Also I have noted that in some of these the insulating white plastic is shattered. Are these really sentenced to be thrown away?

branadic:
Who cares if they don't meet their initial tolerance, unless their true value is known and written on the units?

-branadic-

jonpaul:
Hello: Guarded three term or just 2 term measurement? Is the Wayne Kerr in CAL?

These are very well designed classics and can be repaired.

A CAL lab can CL them.

If you want to throw them I will take them for the cost of shipping !


PM me if you like

Kind Regards,

Jon

dzseki:

--- Quote from: jonpaul on January 24, 2022, 02:52:56 pm ---Hello: Guarded three term or just 2 term measurement? Is the Wayne Kerr in CAL?

--- End quote ---

2 terminal (floating) measurement were done, the Wayne-Kerr is in CAL, infact we also have a classic HP 4280A (also in CAL), which reads these sligthly beyond limit. The HP is fixed at 1MHz and I know the accuracy has a function with the measurement frequency, but still too high.

At the moment I have no plans to throw them away :)

Henrik_V:
While 'stored' outside... these caps are free air caps (not sealed cans like the 1404) .. maybe they need some drying?

Nice found.. Some time ago I harvested some 1404 1nF cans (only the cans) build by Quadtech .. some failed due to whisker .... 

Can you send a pic of the 1pF open? 

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