LC meter


Date: Sun Jun 04 1995 - 20:56:39 EDT

Those who are wont to re-read back issues of mags may come across an old 73
article (July '90) which describes how to build a device to measure inductors
(coils) and capacitors using a simple circuit and a trusty Commodore 64.
 This device is so accurate, you will find it beats or equals most portable
digital meters. One flaw in the article was that the programming as written
would read out very small caps in natural logs instead of decimals, making it
unusable for those who don't know how to convert--inconvenient for those who
do. (I haven't tried since college--so I can't actually claim to know how
myself.) Anyway, I have rewritten the necessary portion of the short program
from the article to convert the small value caps into pf readouts for my own
use, and anybody who wants the rewrite can email me. This gives the device
quite a wide range of very accurate readout. Since it is on the C64, I will
have to print and photocopy it, so to save me unnecessary postage, let's say
I'll send it free to those who have the device already working. If you plan
to build one, save this message and drop me an email when you have the sucker
working. (The original program in the article works fine for caps .001 and
larger.) Parts are waiting at your local Radio Shack, and the schematic is
fine in the mag.
    This may not be exactly QRP, but it is very useful for the homebrewers
here. I note that the L meter was used in my shack to find a wrong coil form
(no, I have no idea how I made that mistake! That was a new way to foul up,
for me.) in my new (finally working) SW80--well reviewed already in QRPp--so
I will only add some comparative impressions after I have it on the air a few
days. 72, all. Preston WJ2V

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