[Milsurplus] AN/GRR-5 Power Supply Questions

[Neil Barnett]

----- Original Message ----- 
From: "WF2U"

> ABSOLUTELY not true! The voltage rating of electrolytic capacitors, just
> like that of any other capacitor indicates the insulation level between 
> the
> two electrodes which form the capacitance.

Electrolytics differ from ceramic, polyester, and similar capacitors
in that they *require* an applied DC voltage to form and maintain
the dielectric, in a complex chemical action.  If you don't apply a
certain minimum DC voltage, the electrolytic capacitor won't reach
its rated capacitance.  To ensure that it does, the applied voltage
should be not less than about two-thirds of the marked Working
Voltage.

> "Forming" an electrolytic capacitor also has
> nothing to do with "attaining their full capacitance".

Here's what the ARRL Handbook (1995) says:  "The actual
dielectric is a very thin film of insulating material that forms on one
set of plates through electrochemical action when a dc voltage is
applied to the capacitor."   (page 6.9).

And, "Electrolytics should not be used if the d.c. potential is well
below the capacitor working voltage."   (page 10.5).

And the 1992 Handbook says:  "A dielectric is "formed" by the
voltage applied to the capacitor.  As a consequence, electrolytics
should not be used where the dc potential is well below the capacitor
working voltage."   (page 26.22).

73 de Neil ZL1ANM