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LF: Re: Re: 500 / OLB test-sig...

To: <[email protected]>
Subject: LF: Re: Re: 500 / OLB test-sig...
From: "GW3UEP" <[email protected]>
Date: Fri, 3 Aug 2007 16:15:09 +0100
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References: <005001c7d3fe$e4786d80$6400a8c0@oem17oeylz9on8> <001901c7d42b$e6fbeaa0$86048351@w4o8m9> <00a001c7d43c$f4180690$0a7ee150@o> <[email protected]> <[email protected]> <003001c7d4d1$fcaf0390$db3a383e@Tom> <000101c7d5a4$5f527220$4e69e150@o> <008901c7d5b0$eea7c040$a17d383e@Tom>
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Tom,
I use the L-match on all ants, from half-waves to verticals, with a simple differential version for open-wire doublets.
Currently, I have ~3000pF across the 50R coax at the remote feed on MF [the resonating vario/L forms part of the L-match].
Your 6600pF is a good indication of a low input-resistance and resistive transformation from 50R downwards towards the ant.
Coincidentally, Mike has just tried the L-match with my sensitive resistive-reflectometer cct - he nulled at 5600pF.
Your R_in looks like ~24R [Mike's ~28R]; mine is an appalling ~40R.
Rog.
 
P.S.
I use the L-match to arrive at  i/p resistance by measuring the C/L values of the nulled cct.
Then, use RFSim to simulate the ant load & find X & R_in.  The results can be verified by substitution on the bench.
A really good/low R_in [<10R] will require ~15000pF or more on MF.
 
 
 

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