[Elecraft] Resistance Readings with Digital Volt Meter

Wed Jan 2 15:51:05 2002

George,

I was lucky enough to be going through Electronics classes in college with 
a Simpson 260, a VTVM, a Fluke 87 digital multimeter, and an inexepensive 
manual ranging digital multimeter available to us for testing.  We did a 
lot of playing around with the different meters after a couple of texts we 
had didn't correctly instruct us to do what actually worked with all of the 
meters.

A VOM with a digital readout would read differently than a manual ranging 
VOM with a digital readout.  And it would have the voltage configured as 
you said.  From what Mike said in his message, I think he was using a 
Micronta Digital Multimeter with a manual range selection.

Some time back, there was some discussion on the main Elecraft forum and 
the Elecraft field test forum about the differences between the different 
types of meters.  As I remember, the recommended meter for building an 
Elecraft is some kind of digital multimeter because of its characteristics 
on measuring volts and resistances.  The main concern in choosing a DVM for 
building the kits is that the other meters have exactly the charactistics 
you describe.

Hope this clarifies things a bit.
Tim Raymer
73 de KA0OUV

At 19:41 12/31/2001 -0600, George, W5YR wrote:
>...but are you sure that it is a true digital VOM or a regular analog VOM 
>with some sort of digital readout?
>
>Your problem sounds like you are using a conventional analog VOM which can
>yield different results when used to measure in-circuit components. Also,
>such meters usually have the black or negative test lead with a positive
>voltage on it when measuring resistance. The true DVM does not.
>
>And finally any readings made of components in a circuit necessarily
>include the effects of all the other circuit elements that are connected.
>
>"Timothy A. Raymer" wrote:
> >
> > Mike,
> >
> > That is a common problem with meters.  Best thing is to pick the next
> > highest full scale reading to check it.  So, if you have a reading that is
> > 1kOhm, you would select the 2kOhm scale.  Since this one is >100k, you
> > should get the most accurate reading with the 200k scale.
> >
> > Tim Raymer
> > 73 de KA0OUV
> >
> > At 09:04 12/31/2001 -0600, Mike Willey wrote:
> > >I have a question on the prelimary test readings on my K1 sn
> > >998  (Actually, it is more a question about taking the ohm meter readings
> > >with my digital volt meter)
> > >
> > >For the test points that should read >100k Ohms, I get different readings
> > >depending on what scale I am reading on the ohm meter.  I am using a
> > >Micronta meter I purchased at Radio Shack several years ago that has the
> > >following Ohm meter ranges 200, 2k, 200k 2m 20m.. For the test points in
> > >question, I get different readings on the 200k, 2m and 20m range.. All
> > >readings are OK on the highest range, but may be close in the 200k range..
> > >
> > >The meter reads purely resisitive loads (resistors) fine on all ranges..
> > >
> > >Any ideas from anyone..
> > >
> > >Thanks
> > >
> > >Mike Willey
> > >WA1GWE

Timothy A. Raymer               <[email protected]>
Missouri Department of Health   <[email protected]>
and Senior Services