[Amps] measuring rf colis

Conrad_G0RUZ conrad at g0ruz.com
Tue Jan 24 21:15:11 EST 2006


Don't MFJ recommend putting a known value capacitor in parallel with the
coil and measuring the resonance? Then as you know the capacitors value ± 5%
and the MFJ frequency ± 5% you should be able to calculate the approximate
inductance of the coil for large inductors at lower frequencies at least.
Forget it in the VHF region though, stray C between turns become very
significant. I use an AADE LC Meter II and I am delighted with it, it comes
up with very accurate results on some lab standard inductors that we have at
University. Here is a link
http://www.aade.com/lcmeter.htm

73

Conrad G0RUZ

> -----Original Message-----
> From: amps-bounces at contesting.com 
> [mailto:amps-bounces at contesting.com] On Behalf Of Will Matney
> Sent: 25 January 2006 01:47
> To: amps at contesting.com
> Subject: Re: [Amps] measuring rf colis
> 
> Chuck,
> 
> Most stock chokes are measured at frequencies around 1 and 10 
> kHz using a precision LCR (bridge) meter. I have both the 
> analog and digital bridges here and use both. There are some 
> LCR meters by HP and a few others which can measure up to 10 
> MHz. Most all stock coils though like Ohmite are measured at 
> around 1 to 10 kHz. The three top manufacturers of LCR meters 
> is HP, ESI, and GenRad.
> 
> Best,
> 
> Will
> 
> *********** REPLY SEPARATOR  ***********
> 
> On 1/24/06 at 7:51 PM Partain, Chuck wrote:
> 
> >probably touched upon 10k times but..
> > 
> >Using my MFJ-259b, measuring some rf coils I have here, sweep the 
> >frequency...
> >all coils I have, move all over the place. Is there a standard 
> >frequency these are rated at?
> > 
> >say a coil is advertised at 10uh. at what frequency? I can 
> pretty much 
> >determine the current by the size of the wire...??
> > 
> >chuck
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> 
> 
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