[R-390] DMM bounce

[Dan Merz]

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.