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LF: Re: Re²: Tune the loop...

To: [email protected]
Subject: LF: Re: Re²: Tune the loop...
From: "captbrian" <[email protected]>
Date: Fri, 13 Aug 2004 12:05:05 +0100
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]>
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Merci,
 I wonder why you don't use the commonplace  (for higher frequencies ) small  loop inside the bigger one for impedance transformation and variable coupling?. Notice I am learning from others' mistakes before making my own loop  :-))
 
Bryan G3GVB
----- Original Message -----
From: F6CWN
Sent: Friday, August 13, 2004 11:07 AM
Subject: LF: Re²: Tune the loop...

13./08/2004   0944z
 
 Good morning Bryan,
 
 The impedance ( in my case, for the loop # 005 ) is around 65 KOhms mesured
at the tune resonnace with a network analyser.
The mesure is not very easy to do because the loop pick up signals...
I tryed to pack the loop with chicken wire netting, and put then to the ground,
like a Faraday box. This is not a fine system, because the network analyser need
an external AC power line... :0)
To know the impedance is not very important opposite to the high Z of the input
of the active impedance adaptater ( many M Ohms).
The most important thing is the quality of the tune capacitor to keep a high Q and
consequently a narrow band pass ( R // to L)
In a next time a will try to use a air butterfly capacitor (~ 500 pF) to tune the complete
band. To my knowledge, this component do not exist, then: "to it yourself!"
If you are rich (this is not my case!), you can try to use two vaccum capacitors in
 differential structure. (why not!)
Higher is Q, better is the noise immunity!
 
"So many thingamajig to do, so short time!"
 
Cheers: Jeff
 
 
From: captbrian
Sent: Friday, August 13, 2004 8:01 AM
Subject: LF: Re: Re: Re: Re: RX in OZ

,,,and what is the impedance at the ends of the loop _before_ Z translator ? ?
 
S.V.P
 
Bryan
 
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