Return-Path: Received: from rly-dd04.mx.aol.com (rly-dd04.mail.aol.com [172.19.141.151]) by air-dd10.mail.aol.com (v123.4) with ESMTP id MAILINDD101-b7549d4bae5141; Thu, 02 Apr 2009 09:17:43 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dd04.mx.aol.com (v123.4) with ESMTP id MAILRELAYINDD047-b7549d4bae5141; Thu, 02 Apr 2009 09:17:26 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1LpMmS-0001al-71 for rs_out_1@blacksheep.org; Thu, 02 Apr 2009 14:16:28 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1LpMmR-0001ac-G2 for rsgb_lf_group@blacksheep.org; Thu, 02 Apr 2009 14:16:27 +0100 Received: from mail.cz.gmc.net ([77.48.211.230]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1LpMmO-0006pU-KL for rsgb_lf_group@blacksheep.org; Thu, 02 Apr 2009 14:16:27 +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; Thu, 2 Apr 2009 15:15:35 +0200 Message-ID: From: =?iso-8859-1?Q?Petr_Mal=FD?= To: References: <20090402074911.6B552F3866@smtps02.kuleuven.be> <1LpKtN-16pRzc0@fwd02.t-online.de> In-Reply-To: <1LpKtN-16pRzc0@fwd02.t-online.de> Date: Thu, 2 Apr 2009 15:15:34 +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-Karma: unknown: 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_0152_01C9B3A5.DF1A0550" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.3 required=5.0 tests=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_0152_01C9B3A5.DF1A0550 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable T-Online eMailHello Ha-Jo Thanks for your suggestion. My transmatch woud be used mainly for RX, howeve= r, I still believe that a tuned antenna is better than detuned one. At least= it is a good preselection for RX. Most of the RX's have just a LPF at these= fq's and therefore they are "broadband" in some way. The transmatch is then= the only tuned circuit in front of the RX. I am still wondering whether a standard Pi network could be used? There woul= d be two large banks of condensers on both sides (high voltage ones on the s= ide of ant) switched by rotary switches. Fine tuning would happen by the var= iometer in the middle. The only disadvantage would be that on the lower end=20= of range (say 50 or 100 kHz) the vario inductivity would be too low and tuni= ng would be difficult (woolly), while on the higher end (550 kHz), it would=20= be too high, tuning would be rather sharp and losses in the vario also rathe= r high. Could this work? 73, Petr ----- Original Message -----=20 From: hajo.brandt.dj1zb@t-online.de=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, April 02, 2009 1:15 PM Subject: Re: LF: Tune and match the ant for 50kHz...550kHz Dear Petr, I guess the easiest solution would be to seperate receiving and transmitti= ng. For receive it is not necessary at all to tune the antenna. I am using my=20= LF T-antenna for receive from 10 kHz to 30 MHz (in addition I also have an u= ntuned wire loop covering 10 kHz to at least 500 kHz, pointing to the north)= . Tuning the antenna would just increase the antenna noise too, as SM6BHZ ha= s also told me. You may just need somewhat more amplification before the rx,= and possibly an rx preselection before this preamplifier. Concentrating on just tuning the antenna for transmitting on either 136 kH= z or 500 kHz would be much easier. And, by the way, the "sphere in sphere" variometer has a big drawback: It= s Q is quite OK at maximum inductivity but very poor at its minumum. Explana= tion is simple. Just assuming the resistance of the wire being constant, at=20= low inducitivity the relation XL to R becomes very poor. 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 variometer=20= 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 of=20= 11. The variometer comes from an 500kHz marine transmitter and it would be r= ather complex to build a copy (mechanical). Running low power you could use a parallel LC circuit. One end to the an= tenna and the other end to ground. The TX is connected to a tap at the coil,= close to ground. You can tune the antenna to resonance by changing C (varia= ble capacitor) and match to 50 Ohm by changing taps on the coil. I did that=20= with success in the early days on 136kHz, but I could run only 30W power bef= ore the capacitor (plate distance 2mm) started arcing.=20 Now you will need a capacitor with a ratio of 121, but that is not so ha= rd: most variable capacitors have a range of 20 or better and you can put so= me fixed capacitors in parallel (via switches). 73, Rik ON7YD At 09:26 2/04/2009, you wrote: Hi all, =20 I want to make a small transmatch (RX, TX up to 10 Watts, or so) to tu= ne 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 s= ystem is the popular loading coil (home made variometer, and taps to find 50= Ohms match). The simple variometer (cylindrical coil in another cylindrical coil) i= s easy to make and works fine on 136kHz. However, it is possible to change i= nductance in the range about 1:2 or 1:3 only, not much better. Therefore the= redudant inductance is too high to fetch the ant to resonance on 550 kHz. Solution would be to make a more sophisticated variometer (best: spher= e in sphere) to reach the ratio 1:10 or so. Or, to use a different kind of network. Pi network, L network or T net= work. BTW I would also prefer to use a rotary switch and solder twenty conde= nsers rather than to make twenty taps on a coil wound with litz wire... =20 How did you solve this yourself? =20 Thanks, 73, Petr, OK1FIG =20 =20 =20 Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm for more in= formation.=20 =20 ------=_NextPart_000_0152_01C9B3A5.DF1A0550 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable T-Online eMail
Hello Ha-Jo
 
Thanks for your suggestion. My transmatch w= oud be=20 used mainly for RX, however, I still believe that a tuned antenna is better=20= than=20 detuned one. At least it is a good preselection for RX. Most of the RX'= s=20 have just a LPF at these fq's and therefore they are "broadband" in some way= .=20 The transmatch is then the only tuned circuit in front of the RX.
I am still wondering whether a standard Pi=20= network=20 could be used? There would be two large banks of condensers on both sides (h= igh=20 voltage ones on the side of ant) switched by rotary switches. Fine tuning wo= uld=20 happen by the variometer in the middle. The only disadvantage would be that=20= on=20 the lower end of range (say 50 or 100 kHz) the vario inductivity would=20= be=20 too low and tuning would be difficult (woolly), while on the higher end (550= =20 kHz), it would be too high, tuning would be rather sharp and losses in=20= the=20 vario also rather high.
Could this work?
 
73, Petr
 
----- Original Message -----
hajo.brandt.dj1zb@t-online.de=20
Sent: Thursday, April 02, 2009 1:15= =20 PM
Subject: Re: LF: Tune and match the= ant=20 for 50kHz...550kHz

Dear Petr,
<= BR>I guess=20 the easiest solution would be to seperate receiving and=20 transmitting.

For receive it is not necessary at all to tune the=20 antenna. I am using my LF T-antenna for receive from 10 kHz to 30 MHz (in=20 addition I also have an untuned wire loop covering 10 kHz to at least 500=20= kHz,=20 pointing to the north). Tuning the antenna would just increase the antenna= =20 noise too, as SM6BHZ has also told me. You may just need somewhat more=20 amplification before the rx, and possibly an rx preselection before this=20 preamplifier.

Concentrating on just tuning the antenna for=20 transmitting on either 136 kHz or 500 kHz would be much easier.

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

OK?

73 Ha-Jo, DJ1ZB 


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

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

73, Rik  ON7YD
At=20 09:26 2/04/2009, you wrote:
Hi=20 all,
 
I want to make a small transma= tch=20 (RX, TX up to 10 Watts, or so) to tune LW 41 m (or smaller T-ant) in t= he=20 range 50 ... 550 kHz.
I am not too good in theory... but I believe=20= that=20 the most efficient system is the popular loading coil (home made=20 variometer, and taps to find 50 Ohms match).
The simple variometer=20 (cylindrical coil in another cylindrical coil) is easy to make and wor= ks=20 fine on 136kHz. However, it is possible to change inductance in the ra= nge=20 about 1:2 or 1:3 only, not much better. Therefore the redudant inducta= nce=20 is too high to fetch the ant to resonance on 550 kHz.
Solution woul= d be=20 to make a more sophisticated variometer (best: sphere in sphere) to re= ach=20 the ratio 1:10 or so.
Or, to use a different kind of network. Pi=20 network, L network or T network. BTW I would also prefer to use a rota= ry=20 switch and solder twenty condensers rather than to make twenty taps on= a=20 coil wound with litz wire...
 
How di= d you=20 solve this yourself?
 
Thanks, 73, Pe= tr,=20 OK1FIG
 
 
 


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

 =20
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