Hi Jim...
The BK875 is a wonderful meter, along with a number of others, for LC work.
However, for those of who wont', or can't, justify the cost, may I recommend
the DM4070. Its available on ebay, and other places, for about $40, and
compares within couple of percent of the "lab grade" instruments. I have 4 LCR
meters, and its the one that gets used the most, or lent out upon request.
Simply outstanding meter for the price.
Much can be made about reading small inductors with these meters... below 1uh
to tenths or hundredths of a uh. I don't put much stock into it; the reading
will change depending on where the probes are connected on the component
leads... they are that sensitive. The realization that final adjustment with
small coils must be made with a squeeze or a push after installation, with
extraneous material cut, off comes pretty fast.
Most of the time, my different LCR meters will read closely. However, there
are times they aren't, and then I keep in mind the core material, number of
windings, and the meters test frequency. Strangely enough, sometimes it hard
to say what the actual value of a particular winding is after measuring it with
a couple of instruments and finding "large" discrepancies. I've always blamed
"core leakage" and not measuring near the actual operating frequency. Seems
to happen mostly on multi-winding non-ferrite cored materials.... any thoughts
on that?
Not many problems measuring either C or R, though I do put caps through a
leakage check at their rated voltages. I can also measure ESR but don't
generally employ that technique outside of a switching power supply.
Jamie, K9JFK
Previously >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
## I use my B+K 875-B LCR meter to test hv lytics. The 875-B and other
similar meter's will read as high as 20,000 uf. It will also read D factor..and
that feature alone will find a bad cap instantly. The 875B reads AC
resistance and not dc
resistance..and down to .001 ohm. With this last feature, you can measure the
ESR of each cap
as well. After going through case loads of new caps, they will typ all read
the same esr,
within 1 milliohm of each other, at least for a quality brand of hv cap.
## That 875-B is worth it's weight in gold. #1 amp tool in the shop. Being
able to read down to
.1uh and .1 pf saves a lot of time and effort when either winding coils or
measuring coils, or
measuring caps, and stuff like stray C, tube C, effects of AL side walls,
partitions, etc.
The latest B version I have will also allow to zero out the test leads when on
the uh mode, or
resistance mode..and ditto with C mode.
## for testing HV lytics, the caps have to be discharged 1st of course.
Depending on brand,some
hv caps are way on the high side, and some brands are way on the low side. I
also have the older
B+K 875-A. They come with a 3 year warranty, industry standard piece of
test gear. They are
cheap at Mouser.
Later.... Jim VE7RF
Unquote>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>Un
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|