In a message dated 23/01/05 12:19:41 GMT Standard Time, [EMAIL PROTECTED] writes:
The really confusing aspect of it all is a 270 pfd capacitor should be labelled "271", so you have the case where something marked "270" isn't a 270 pfd capacitor. --------------------------------------------------------------------- The problem with marking small capacitors is providing the value on them so that it is more easily readable. What the manufacturers of the bulk of the capacitors now used by Elecraft is that the last digit of the three provided is the multiplier. This is just the same as with resistor color codes. Following this a capacitor marked 271 is 27 with a multiplier of 10 = 270 pF (27 x 10 = 270). For a 27pF capacitor this would be marked 270 = 27 with a multiplier of 1. (27 x 1 = 27) This can be useful when higher values of capacitor are used. For example 0.1uF = 100nF = 100,000pF and would be marked 104. This is 10 with a multiplier of 10,000 (10 x 10000 = 100,000pF). After a while reading the capacitor values becomes automatic just as one learns to read the resistor color code. Not really sure which way I read the values of resistors, but suspect I look at the last digit first to see the multiplier and then the value within that multiplier. Now do the same with the capacitors that Elecraft use. The problem arises with this capacitor marking system with values below 10pF cannot be accommodated and manufacturers either resort to just providing the value direct or adding a *p* where the decimal point should be. Philips use the *p* or the *n* for marking their capacitors. This means a 2.7pF capacitor would be marked 2p7 and a 0.1uF or 100nF capacitor would be marked 100n.To be sure I check all the values of the capacitors in doubt with the capacitance measuring facility in my DVM. A large proportion of the DVM seem to have this facility provided even down to the low cost versions and at least my $50 DVM will measure down to single digit pF values with reasonable accuracy. Bob, G3VVT _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
