From: John Woodgate
Subject: Re: Resistors for r.f. applications
Date: Fri, 3 Jan 2003 07:22:34 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Fri, 3 Jan 2003 11:00:36 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Barry Lennox
wrote (in ) about 'Resistors for r.f. applications', on Fri, 3 Jan
>On Thu, 2 Jan 2003 22:20:10 +0000, John Woodgate
>>I tried a web search for resistors that stay resistors, and about the
>>same value, up to at least 10 MHz, but found it surprisingly difficult
>>to find anything. I need some 50 ohm 0.5 W and some low values like 1
>>ohm, very low power.
>Carbon comp will do, but are a bit hard to find these days. Be wary
>though, as different types of carbon comps behave diffently. We had a
>225-400 MHz power amp (made by ITT, IIRC) that would only behave with
>some brands of carbon comps, others would make it oscillate at the top
>end. They looked identical, but were not!
Yes, that's what I've found. I have some 47 ohm carbon comp parts, but
they aren't 47 ohms at 10 MHz.
>SMD will also work well, take a look at http://emcesd.com/1ghzprob.htm
>I have also used a 1.2 Ohm, 0603 SMD as a dummy squib, it was flat and
>resistive to at least 1.6 GHz, the far bigger problem was the physical
>transistion from coax to the SMD part. Just looked as I have a reel of
>about 4999 of them!, they were from Newark and mfg by Xicon.
I have some SMD parts but I haven't worked out a way of using them in an
experimental set-up. Thank you.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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