[volt-nuts] Anyone know how to make stable inductors?
Dr. David Kirkby (Kirkby Microwave Ltd)
drkirkby at kirkbymicrowave.co.uk
Tue Sep 1 09:09:21 EDT 2015
On 20 August 2015 at 02:38, Todd Micallef <tmicallef at gmail.com> wrote:
> Here is a DIY guide to making some lab standards. It is detailed with some
> component values.
As I wrote before, I think this is of dubious use, as you are not making an
inductor, but just making the meter indicate there's a low Q inductor, by
using the 4-wires in an incorre
> On Wed, Aug 19, 2015 at 8:48 PM, Dave M <dgminala at mediacombb.net> wrote:
> > Here's a paragraph from IETLab's web site on how their inductance
> > standards are made:
> > "Each standard inductor is a uniformly wound toroid on a ceramic core. It
> > has a negligible external magnetic field and hence essentially no pickup
> > from external fields. The inductor is resiliently supported in a mixture
> > ground cork and silica gel, after which the whole assembly is cast with a
> > poƫting compound into a cubical aluminum case."
> > Sounds like their objective is to isolate the winding from as many
> > external influences as possible. Of course, the same couild be said of
> > physical or electrical standard.
> > Cheers,
> > Dave M
> > Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
> >> I was looking to make some inductors that I can use as a sanity check
> >> for
> >> my HP 4284A LCR meter. I don't too much care what their values are,
> >> but I want them to be stable with time. Any suggestions about the
> >> best way to
> >> make or buy them? I'd like values in the range of 1 nH to 100 mH.
> >> The LCR meter has 4 terminal Kelvin connections, with 4 x BNC sockets
> >> on a 22 mm pitch.
> >> The meter is at Keysight at the moment being calibrated, along with a
> >> free software upgrade they are kindly providing. So I'd like to
> >> measure some inductors when it comes back, and track their values
> >> over time, to see if the meter is drifting.
> >> The meter covers 20 Hz to 1 MHz, and has a basic uncertainty of
> >> 0.05%, so ideally I'd like to keep inductor changes to less than
> >> 0.005% over a year, so the inductor is an order of magnitude better
> >> than the meter. Maybe that is not practical. As I say, the absolute
> >> value is not important, since I only want a comparison.
> >> The calibration costs on this meter are not too bad (£207 GBP), but
> >> the calibration interval is 6 months, which is a bit annoying. I'd
> >> rather not
> >> be sending it off every 6 months if I can satisfy to myself it has not
> >> drifted too much. Luckily I don't need to satisfy anyone else.
> >> Dr. David Kirkby Ph.D CEng MIET
> >> Kirkby Microwave Ltd
> >> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex,
> >> CM3 6DT, UK.
> >> Registered in England and Wales, company number 08914892.
> >> http://www.kirkbymicrowave.co.uk/
> >> Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
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