KISS .......but here S stands for SMART.
Jos on4kj
Merry XMS and Happy 2006 to ALL
-----Message d'origine-----
De : amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] De
la part de Dave Haupt
Envoyé : mercredi 21 décembre 2005 22:28
À : amps@contesting.com
Objet : Re: [Amps] Ohmite thick-film resistor L measurement
Series L could hardly be easier in this case. You can
even use your rig, assuming it's broadbanded.
Use the 100 ohm resistor as a load. At low
frequencies, it will measure SWR=2:1. Raise the
frequency until you see the SWR rise to some
convenient value at which you trust your measurement
device - 2.5:1 or 3:1 for instance. Assume the rise
is caused by series inductance.
Now, plot the SWR=2.5:1 or SWR=3:1 circle as
appropriate on the Smith Chart. Follow the Rnorm=2.0
line up from the X=0 line until you hit the SWR circle
you've drawn. Read off the Xnormalized, and a few
little multiplies and divides and you'll have the
series inductance.
Alternatively, an RF sig gen, a one ohm carbon comp
1/4 watter and a two-channel scope can do it the
old-fashioned way by measuring V and I and dividing
them.
73,
Dave W8NF
>>R.Measures wrote:
>> ??? I need to find someone who can measure the L
of an Ohmite type TAP
>> 600W, 100Ω thick-film resistor. This resistor
will be used for R-supp
>> in a QRO VHF parasitic suppressor R&D project.
>Unless the reactance is greater than about 650 ohms,
you should be able
>to use an MFJ or similar antenna analyzer -- it will
tell you R and Z
>(or L). Am I missing something?
>--
>73,
>Vic, K2VCO
>Fresno CA
>http://www.qsl.net/k2vco
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