[R-390] DMM bounce

[Dan Merz]

Hi Joe,  my DMM is BK 2905 calibrated with dc and for ac with 400 hz.  I

have no idea yet of  details on the other guy's meters except I think
they are autoranging type for ordinary dc and 60 hz measurements.  I'll
try to get more details on his meter but I don't think they are types
for measuring much above 5 khz.  I use my meter occasionally for
measuring up to 5 khz,  though I have no idea how accurate it really is
up there but I use it to get voltage ratios for evaluating audio
transformers.   I have checked it  against my HP 403B meter and decided
for what I was doing it was good enough.   It reads about 3% low at 12
khz and close on up to 7 khz.    Thanks for any thoughts on my
question,  best regards,  Dan.

Joe Foley wrote:

> What frequency are your voltmeters calibrated for?
>
> Joe
>
> --- Dan Merz <djmerz at 3-cities.com> wrote:
> > Hi,  here's a general question related to making
> > resistance measurements
> > when an inductance is involved,  e.g. the winding on
> > an audio
> > transformer.  Generally,  I make such measurements
> > either with my BK
> > DMM on a fixed scale setting or with a Simpson 260
> > old-style
> > multimeter,  and I usually have no problem.  But
> > recently I repaired an
> > audio transformer and sent it to the lucky guy and
> > he emailed that the
> > primary was ok but his digital meter just bounced on
> > the secondary and
> > never settled on a reading.  I thought maybe I made
> > a bad solder
> > connection.   The approximate inductance of this
> > secondary is about 360
> > henries.  He sent it back to me and I measure it as
> > ok,  about 1500
> > ohms,  using my usual methods.  I do notice that the
> > reading shows a
> > couple of high reading before settling down.  This
> > doesn't happen on the
> > primary which is much lower inductance.  My question
> > - are there some
> > DMMs,  maybe the autoranging types,  that have
> > problems with such
> > measurements.  I could imagine this could happen
> > depending on the rate
> > at which it tries to "range" the reading but it
> > would seem that it
> > should eventually settle down.  He tried it with two
> > different digital
> > meters and couldn't get a stable reading.  I
> > sometimes use this
> > measurement method on 390a parts,  hi.   Hopefully
> > waiting for
> > illumination,  Dan.
> >
> >
> >
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