Capacitor Question for my Predicta

[Old1625]

You might try Pittsfield Radio for that capacitor; I used to get all kinds of capacitors there back in the early '70s--including the one you mention, I'm sure--while I was building radio prototypes. They may have some left in inventory. Next time I'm in there I can check for you. 413-442-0901 and speak to Alex. Or John. Best to indicate straight off that David Locke sent you. They will be closed the first part of this week, but should be open Weds-on from 1 to 5PM.

That capacitor may well be OK left alone if it is a ceramic disk, domino or dog-bone type, if you are merely "shotgunning" the assembly. If you have diagnostic reason to believe there are issues then that's another story.

If the capacitor is in RF-related circuitry then that N330 temperature coefficient will be apt to be critical. But sometimes it is not, and the coefficient is present simply because that's what the maker had in stock for the board stuffers to grab.

The N330 designation means that the capacitor will have a variance of 330 parts per million over a standard range of temperature, with the "N" indicating that the capacitance will drop as temperature rises.

The site http://www.mitron.cn/product/23-Resi...mpCompCaps.pdf gives a graph that well illustrates this.

That inductors and other components in a critical RF circuit application can change their characteristics with temperature engineers relied on this selection of caps with different temp coefficients to help them compensate for these tendencies so that the circuit would remain stable over a reasonable defined temperature range.