[Elecraft] CAPACITOR VALUES

[Ron D'Eau Claire]

Don't know which DMM you are using, John. I have a Radio Shack DMM that
features capacitance scales, but switching it to capacitance with NO =
leads
attached shows a reading of 111 pF. I will ready values as low as 5 pf =
quite
accurately IF I use the front panel jack for diodes/resistors/caps (no
leads) and IF I allow for the 111 parasitic capacitance in the meter. =
That
is, a 5 pf cap will read 116 pF on the meter.=20

Of course large value caps are unaffected by the parasitic capacitance =
when
111 pF is a tiny percentage of the total.=20

 Your meter seems to be showing a parasitic value in the 20-30 pF range =
that
varies. I suspect you were using leads. Leads add odd amounts of =
capacitance
that will change with small movements, so it's not really very practical =
to
try to use them to measure small caps.=20

Ron AC7AC

-----Original Message-----
Encouraged by the book to do so, I checked all the capacitor values.   I =
had
just purchased an autoranging DMM with a capacitance measuring feature =
(the
first time I have ever owned such a device) and began to go through the
packets.   All the monolithic caps checked out fine, so did the
electrolytics but, when I turned to the NPO caps, I began to get very
strange readings from most of them.

For example:

    1 pf    read     21 pf
    10pf    read    35PF
    12pf    read     38pf
    20pf    read    51pf
    27pf    read    62pf
    33pf    read    70pf
    39pf    read    77pf
    47pf    read    90pf
...John   ZL3LI