Pete, others,
that monograph is also available at .
The joy of the Internet Archive is that:
a) no attachment is required
b) frequently (as in this case) a Sandwich PDF is available (an
integral OCR process produces a scanned PDF with searchable and
selectable text, which is frequently useful)
HTH, 73, Stay Safe,
Robin, G8DQX
PS: No wonder Star Trek's version of Q is such a troublesome
character!
On 18/08/2022 14:50, Pete_G4GJL wrote:
A 1955 Monograph?from the Bell Labs Series.
?Some might find this an interesting background,?else
delete.
Pete
G4GJL
On Tue, Aug 16, 2022 at 7:56
AM Dr. David Kirkby, Kirkby Microwave Ltd <
drkirkby@...>
wrote:
On Tue, 16 Aug 2022 at 01:14, Labguy <
georgg@...>
wrote:
There is an
interesting engineering note from Vishay on the
subject of measuring inductance with various pieces
of test equipment (including the 4342A) at various
frequencies. They quote up to 100% variation in
readings on a single test sample (!)
"Frequency Dependance of Inductor Testing and
Correlation of Results Between Q Meters and
Impedance Meters" (sic)
Google: Vishay 34093
Their conclusion was to stick with the 4342A.
Cheers,
George
VK2KGG
If you are talking about the same
document I think you are,
I am not impressed by the
methodology in that document?
They have taken a selection of
instruments (a Q-meter, inductance meter, LC meter
and impedance analyzer), and tested one inductor at
specific frequencies (130 kHz, 1 MHz, 10 MHz, 25 MHz
and 100 MHz). The measured value varied between
594.0 nH & 1300 nH.? At only one frequency (130
kHz) were two instruments used to measure the same
device
Surely it would have been sensible to
provide further results.
1) At a frequency at which all the
instruments will operate (1 MHz). Then you are
comparing apples to apples.
2) Show how the measured inductance
changes with frequency on the HP 4342A Q-meter.
Their only real reason for staying they will
continue to use the results that would be measured
on a HP 4342A Q-meter, is that historically it has
been done that way. They even say they will not
necessarily use a?
HP 4342A Q-meter for the testing.
One interesting? couple of
measurements were made using the Tektronix LC130
L&C? meter and the HP 4192A impedance analyzer.
The Tektronix LC130
indicated L=1300.0 nH and the HP 4192A impedance
analyzer indicated L=607 nH at the same frequency
of 130 kHz. That's a pair of measurements
taken under similar conditions, but giving very
different answers.
An interesting trio of measurements were at 130
kHz, 1 MHz and 10 MHz using 2 different instruments
(HP 4192A impedance analyzer and Boonton 62A
inductance meter). All 3 answers were within 0.17%
of each other, despite the factor of 77 between the
different frequencies.
As you say George, the results of the paper and
intersting, but I felt the note was rather lacking
in substance. I am pretty sure no journal would have
published that as a paper, as there's no analysis of
the results.
Dave
