To: rsgb_lf_group@blacksheep.org References: <002601c480a7$e7ea4400$1600a8c0@hasbro.co.uk> <001501c480ad$373a9460$0fa424d5@jboi0045tiscali> <004501c480b3$58654670$1600a8c0@hasbro.co.uk> <008801c480cc$25700ac0$0fa424d5@jboi0045tiscali> <001d01c4810b$bb41ede0$0e540150@captbrian> <000901c4811d$6730c2a0$da0024d5@jboi0045tiscali> Date: Fri, 13 Aug 2004 12:05:05 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2615.200 X-SPF-Result: relay.thorcom.net: 62.253.162.43 is neither permitted nor denied by domain of ukonline.co.uk X-Spam-Score: 0.6 (/) X-Spam-Report: autolearn=no,HTML_40_50=0.474,HTML_MESSAGE=0.001,RCVD_IN_SORBS=0.1 Subject: LF: =?iso-8859-1?Q?Re:_Re=B2:_Tune_the_loop...?= Content-Type: text/html; charset=windows-1252 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_40_50,HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Spam-Filtered: by PlusNet SpamCORE (v3.00) Content-transfer-encoding: 8bit

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

To: rsgb_lf_group@blacksheep.org

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

To: rsgb_lf_group@blacksheep.org

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