Return-Path: Received: from rly-df04.mx.aol.com (rly-df04.mail.aol.com [172.19.156.17]) by air-df06.mail.aol.com (v123.4) with ESMTP id MAILINDF063-54249d9afa71fc; Mon, 06 Apr 2009 03:31:22 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-df04.mx.aol.com (v123.4) with ESMTP id MAILRELAYINDF041-54249d9afa71fc; Mon, 06 Apr 2009 03:30:49 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1LqjH5-0004fd-3r for rs_out_1@blacksheep.org; Mon, 06 Apr 2009 08:29:43 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1LqjH4-0004fU-6G for rsgb_lf_group@blacksheep.org; Mon, 06 Apr 2009 08:29:42 +0100 Received: from mail.cz.gmc.net ([77.48.211.230]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1LqjH1-0006cn-8y for rsgb_lf_group@blacksheep.org; Mon, 06 Apr 2009 08:29:42 +0100 Received: from Lenovo (192.168.100.32) by dove.gmc.net (192.168.40.18) with Microsoft SMTP Server id 8.1.358.0; Mon, 6 Apr 2009 09:29:04 +0200 Message-ID: <65FC7E2034594015B29488202AA874CA@gmc.net> From: =?iso-8859-1?Q?Petr_Mal=FD?= To: References: <20090402074911.6B552F3866@smtps02.kuleuven.be> <1LpKtN-16pRzc0@fwd02.t-online.de> <20090402124918.EBC0B31E703@smtps01.kuleuven.be> In-Reply-To: <20090402124918.EBC0B31E703@smtps01.kuleuven.be> Date: Mon, 6 Apr 2009 09:28:52 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6001.18000 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18049 X-Spam-Score: 0.5 (/) X-Spam-Report: autolearn=disabled,HTML_FONT_FACE_BAD=0.452,HTML_MESSAGE=0.001 Subject: Re: LF: Tune and match the ant for 50kHz...550kHz Content-Type: multipart/alternative; boundary="----=_NextPart_000_0213_01C9B69A.19398A70" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_20_30,HTML_FONT_FACE_BAD, HTML_MESSAGE,MISSING_OUTLOOK_NAME 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-AOL-IP: 193.82.116.20 ------=_NextPart_000_0213_01C9B69A.19398A70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello all, Thanks all for your comments, it helps. I can't recall that anybody would ever mention the possibility to change ser= ial connection of the coils of a variometer to the parallel one.=20 If the ratio is about 1:4, which is still possible to reach with the mechani= cally simple cylinder-in-cylinder design, the ranges will meet each other an= d the overall ratio is about 1:16. BTW there is currently a beautiful loading coil on the eBay. Such items rare= ly appear there. I would buy it myself immediatelly but unfortunatelly the s= eller ships the item to Germany only. Hurry up, about one day remains and th= e price is still only 2 Euro! http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=3D110371392404 73, Petr, OK1FIG ----- Original Message -----=20 From: Rik Strobbe=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, April 02, 2009 2:49 PM Subject: Re: LF: Tune and match the ant for 50kHz...550kHz And, by the way, the "sphere in sphere" variometer has a big drawback:=20= Its Q is quite OK at maximum inductivity but very poor at its minumum. Expla= nation is simple. Just assuming the resistance of the wire being constant, a= t low inducitivity the relation XL to R becomes very poor. I agree on that. Rloss stay more or less constant over the entire range. With my variometer I mearured a Q =3D 430 at maximum inductance (450uH), d= ropping to 50 at minimum inductance (40uH). 73, Rik ON7YD - OR7T OK? 73 Ha-Jo, DJ1ZB=20 "Rik Strobbe" schrieb:=20 Hello Petr, 50-550kHz seems a "big shot". If you want to tune (bring to resonance) the antenna using a variomete= r it would need a ratio of (550/50)^2 =3D 121. The variometer I use on 500kHz has a range of 40-450uH, thus a ratio o= f 11. The variometer comes from an 500kHz marine transmitter and it would be= rather complex to build a copy (mechanical). Running low power you could use a parallel LC circuit. One end to the=20= antenna and the other end to ground. The TX is connected to a tap at the coi= l, close to ground. You can tune the antenna to resonance by changing C (var= iable capacitor) and match to 50 Ohm by changing taps on the coil. I did tha= t with success in the early days on 136kHz, but I could run only 30W power b= efore the capacitor (plate distance 2mm) started arcing.=20 Now you will need a capacitor with a ratio of 121, but that is not so=20= hard: most variable capacitors have a range of 20 or better and you can put=20= some fixed capacitors in parallel (via switches). 73, Rik ON7YD At 09:26 2/04/2009, you wrote: Hi all, I want to make a small transmatch (RX, TX up to 10 Watts, or so) to=20= tune LW 41 m (or smaller T-ant) in the range 50 ... 550 kHz. I am not too good in theory... but I believe that the most efficient= system is the popular loading coil (home made variometer, and taps to find=20= 50 Ohms match). The simple variometer (cylindrical coil in another cylindrical coil)= is easy to make and works fine on 136kHz. However, it is possible to change= inductance in the range about 1:2 or 1:3 only, not much better. Therefore t= he redudant inductance is too high to fetch the ant to resonance on 550 kHz. Solution would be to make a more sophisticated variometer (best: sph= ere in sphere) to reach the ratio 1:10 or so. Or, to use a different kind of network. Pi network, L network or T n= etwork. BTW I would also prefer to use a rotary switch and solder twenty con= densers rather than to make twenty taps on a coil wound with litz wire... How did you solve this yourself? Thanks, 73, Petr, OK1FIG Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm for more=20= information.=20 =20 Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm for more info= rmation.=20 ------=_NextPart_000_0213_01C9B69A.19398A70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hello all,
 
Thanks all for your comments, it=20 helps.
I can't recall that anybody would ever ment= ion the=20 possibility to change serial connection of the coils of a variometer to= the=20 parallel one.
If the ratio is about 1:4, which is still p= ossible=20 to reach with the mechanically simple cylinder-in-cylinder design, the=20 ranges will meet each other and the overall ratio is about 1:16.
 
BTW there is currently a beautiful loading=20= coil on=20 the eBay. Such items rarely appear there. I would buy it myself=20 immediatelly but unfortunatelly the seller ships the item to Germany on= ly.=20 Hurry up, about one day remains and the price is still only 2 Euro!
 
73, Petr, OK1FIG
 
 
----- Original Message -----
Rik Strobbe
Sent: Thursday, April 02, 2009 2:49= =20 PM
Subject: Re: LF: Tune and match the= ant=20 for 50kHz...550kHz

And, by the way,  th= e=20 "sphere in sphere" variometer has a big drawback: Its Q is quite OK at=20 maximum inductivity but very poor at its minumum. Explanation is simple.= =20 Just assuming the resistance of the wire being constant, at low induciti= vity=20 the relation XL to R becomes very poor.

I agree on that.= Rloss=20 stay more or less constant over the entire range.
With my variometer I=20 mearured a Q =3D 430 at maximum inductance (450uH), dropping to 50 at mini= mum=20 inductance (40uH).

73, Rik  ON7YD - OR7T



OK?

73 Ha-Jo, DJ1Z= B=20


  "Rik Strobbe" <rik.strobbe@fys.kuleuven.be>=20 schrieb:
Hello Petr,

50-550kHz seems a "big shot".
If you want to tune (bring to resonance) the antenna using a=20 variometer it would need a ratio of (550/50)^2 =3D 121.
The variometer I use on 500kHz has a range of 40-450uH, thus a rat= io=20 of 11. The variometer comes from an 500kHz marine transmitter and it w= ould=20 be rather complex to build a copy (mechanical).
Running low power you could use a parallel LC circuit. One end to=20= the=20 antenna and the other end to ground. The TX is connected to a tap at t= he=20 coil, close to ground. You can tune the antenna to resonance by changi= ng C=20 (variable capacitor) and match to 50 Ohm by changing taps on the coil.= I=20 did that with success in the early days on 136kHz, but I could run onl= y=20 30W power before the capacitor (plate distance 2mm) started arcing.
Now you will need a capacitor with a ratio of 121, but that is not= so=20 hard: most variable capacitors have a range of 20 or better and you ca= n=20 put some fixed capacitors in parallel (via switches).

73, Rik  ON7YD

At 09:26 2/04/2009, you wrote:
Hi all,

 
I want to make a small transmatch (RX, TX up to 1= 0=20 Watts, or so) to tune LW 41 m (or smaller T-ant) in the range 50 ...= 550=20 kHz.
I am not too good in theory... but I believe that the most effic= ient=20 system is the popular loading coil (home made variometer, and taps t= o=20 find 50 Ohms match).
The simple variometer (cylindrical coil in another cylindrical c= oil)=20 is easy to make and works fine on 136kHz. However, it is possible to= =20 change inductance in the range about 1:2 or 1:3 only, not much bette= r.=20 Therefore the redudant inductance is too high to fetch the ant to=20 resonance on 550 kHz.
Solution would be to make a more sophisticated variometer (best:= =20 sphere in sphere) to reach the ratio 1:10 or so.
Or, to use a different kind of network. Pi network, L network or= T=20 network. BTW I would also prefer to use a rotary switch and solder=20 twenty condensers rather than to make twenty taps on a coil wound wi= th=20 litz wire...

 
How did you solve this yourself?

 
Thanks, 73, Petr, OK1FIG

 

 
 


Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm=20 for more information.

 


Disclaimer: http://www.kuleuven.be/cwis/email_discl= aimer.htm=20 for more information.

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