Re: LF: Re: RF Ammeter

[brian hodgson <g3ykb@yahoo.co.uk>]

Hi J

 

I agree with what Alan says - I've made up three "clamp-on" ammeters using split-core EMC ferrites (500 mA, 2 amp & 15 amp) - they seem to work very well - even up to 4MHz. The two halves of ferrite are glued (expoy resin) to the jaws of strong "hand clamps" with the other components (meter, diode, resistors etc) stuck to the clamp with plastic wood filler.

 

However, for fixed meters eg transmitter output and aerial matching units, I use the regular EMC cores (similar size to the split ones but all in one piece - rather like very large ferrite beads). Its easy to wind the secondary (10 - 20 turns thin enammelled copper wire) and the primary is just the aerial wire poked through the hole. I've also used a 25 mm diam toroid for a 30 amp meter - there wasn't enough space inside the big bead for the 60 turn secondary.

 

GL - Brian (G3YKB) 

Alan Melia <alan.melia@btinternet.com> wrote:

> Toroid splitting seems a lot of effort when you can use an "EMC" split core
> for the transducer quickly and without a lot of effort.

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