Hi all, being lazy and not getting round to building myself anything for
measuring inductance above 1mH directly, I have been wondering about the
meter Dave built last year, and is available I believe from Mainline. I
found the ideal as far as I saw it in a multi-meter with an L range, in the
Metex product range from HF Instruments (who do Andy's A/D and DDS pcb)
Unfortunately Chris advised me that Metex had refused to supply them as they
didn't sell enough. I have been unable to find another
importer/distributor/retailer of the product in the UK.
I spotted an ad buried in the back of Radcom by Chevet Supplies Ltd at
Blackpool for a TENMA LCR meter. There are the usual silly typos in the ad,
the lowest range is actually 2mH FSD on a 3 1/2 digit LCD display, so the
resolution (ls digit) is 1uH though this is well below the strays/zero
error. It goes up to 20H for anyone wanting to load an ELF antenna!! The
measuring frequency is 250Hz so there is not much error due to self
capacity. A quick test show that it measures my loading coils to the same
values that I calculated from resonance tests. Where I found it it quite
illuminating is in investigating the effect of ferrite in the coils. This is
a lot easier to do with a direct reading meter. Unfortunately ( though, not
surprisingly ) the R range is done at DC, I was hoping to investigate ground
resistance with that but it looks like I have no alternative but to build
that bit of kit. Still the Tenma was good value at £44 including vat and UK
carriage.
Chevet also do a stock a wide selection of vintage out-of-print radio books,
so if anybody wants a Terman (or a CR100 handbook) they have several on
offer.( Also Admiralty Handbooks)
www.chevetsupplies.co.uk
Cheers de Alan G3NYK
[email protected]
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