Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-me02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 29E27380000B7; Tue, 29 Jan 2013 08:38:41 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1U0Ary-0007jh-U9 for rs_out_1@blacksheep.org; Tue, 29 Jan 2013 13:04:58 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1U0Ary-0007jY-1w for rsgb_lf_group@blacksheep.org; Tue, 29 Jan 2013 13:04:58 +0000 Received: from mail-qc0-f176.google.com ([209.85.216.176]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.77) (envelope-from ) id 1U0Arn-0007qW-12 for rsgb_lf_group@blacksheep.org; Tue, 29 Jan 2013 13:04:56 +0000 Received: by mail-qc0-f176.google.com with SMTP id n41so164556qco.35 for ; Tue, 29 Jan 2013 05:04:25 -0800 (PST) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:content-type; bh=bczpfVSouMmb0XqiaYlOTlcD8CEKQmLj4Ju6TOhVrBI=; b=Wappz75sDoKsVe+ogEAG8iUCMsBOCwOTmcF1MFf9d7fPykTU9AvPWXyrzZIWUNPAfF cvH5JyoXLEv6sSoPepLBbhtDuFIyUEFBcazWHee3K3PnzQdQt5Hz88dooxwA24z8cMiy bHNtizvDQvQHXiotcJ7Q86EO3k0fJ4BxOjfXF6Y7x9eyxRuBE36hqKZCYd9BQdYUnBxA SNGJmQD/Way+b5c4FFm9w7QkvgYI0CeuLzHIyPncCTT2jqGsaAUPJ7RiX1cI3eqyvHRY X7Q+EqGKK482La/FejA5lz7soJpHlR6qDCR2+ZIaox1INadLyMgfmKK/JXPtNuClubzo WtTg== MIME-Version: 1.0 X-Received: by 10.229.69.32 with SMTP id x32mr207396qci.129.1359464665069; Tue, 29 Jan 2013 05:04:25 -0800 (PST) Received: by 10.229.156.18 with HTTP; Tue, 29 Jan 2013 05:04:24 -0800 (PST) In-Reply-To: <002701cdfe13$d44d1e70$0401a8c0@xphd97xgq27nyf> References: <002701cdfe13$d44d1e70$0401a8c0@xphd97xgq27nyf> Date: Tue, 29 Jan 2013 13:04:24 +0000 Message-ID: From: Roger Lapthorn To: "rsgb_lf_group@blacksheep.org" X-Spam-Score: -0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Robert, 3C90 42mm diameter toroids (and a range of others) are available on-line from Farnell if this helps 73s Roger G3XBM [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [209.85.216.176 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (rogerlapthorn[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: a5eebf1400afcbaf7aee821a75970899 Subject: Re: LF: Re: [rsgb_lf_group] Impedance transformation on 136 kHz - advice needed Content-Type: multipart/alternative; boundary=0021cc020862723ab604d46d0824 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_40_50,HTML_MESSAGE, TO_ADDRESS_EQ_REAL 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-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mtain-me02.r1000.mx.aol.com ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d608a5107d0e02692 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --0021cc020862723ab604d46d0824 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Robert, 3C90 42mm diameter toroids (and a range of others) are available on-line from Farnell if this helps 73s Roger G3XBM On 29 January 2013 11:28, mal hamilton wrote: > ** > > > ----- Original Message ----- > *From:* mal hamilton > *To:* mal hamilton > *Sent:* Tuesday, January 29, 2013 11:22 AM > *Subject:* Re: [rsgb_lf_group] Impedance transformation on 136 kHz - > advice needed > > PS > > Robert > An audio amp is not the best method and inefficient even at 137 Khz. > A better approach is a purpose built amplifier with a couple of FETS clas= s > D or E. There is plenty of info available about building such amplifiers > > > > ----- Original Message ----- > *From:* mal hamilton > *To:* rsgb_lf_group@yahoogroups.co.uk > *Sent:* Tuesday, January 29, 2013 11:19 AM > *Subject:* Re: [rsgb_lf_group] Impedance transformation on 136 kHz - > advice needed > > Robert > Use a capacitor of around 10 uF in series with the amp output then a 4 to > 50 ohm transformer. > Old tv LOPT are suitable or material similar to 3C9 material. > Prim turns around 8 and Sec 28 turns. This is a rough guide to get starte= d > > de mal/g3kev > > > ----- Original Message ----- > *From:* robert_la4ana > *To:* rsgb_lf_group@yahoogroups.co.uk > *Sent:* Tuesday, January 29, 2013 9:51 AM > *Subject:* [rsgb_lf_group] Impedance transformation on 136 kHz - advice > needed > > > > > Hi Group, > > As I am planning to use an audio amplifier as a PA on 136 kHz, I need to > transform the amplifier output (100 Watt at 4-8 Ohm) to 50 Ohm to match > it to the coax cable to the antenna, possibly with a 50 Ohm low-pass > filter in between. Not much information is available on the Internet > about such a specific configuration. I am fond of capacitor impedance > transformation, which I use with success for matching and tuning my loop > antenna on 475 kHz. Could I employ the same concept to step up impedance > from 4 Ohm to 50 Ohm at the output of my audio amplifier? > > I have also looked into using ferrite toroids as transformers but the > sheer amount of information on this subject, often incomplete and > contradictory, is confusing me. It looks like many are using "3C90" as a > core material, but this type of core seems difficult to acquire - at > least for me here in Norway. I understand that "type 77" material could > also be used and this one is easier to get by. If I would opt for an > FT140-77 core, would this be suitable as a transformer toroid for 100 > Watt on 136 kHz or would I need a bigger one? And how many primary and > secondary turns would such a tranformer need to step up from 4-8 Ohm to > 50 Ohm? > > I would be very grateful for some input on this subject before I start > ordering (the wrong) components. > > 73 de Robert, > > LA4ANA > > __._,_.___ > Reply to sender| Reply > to group| Reply > via web post| Start > a new topic > Messages in this topic( > 1) > Recent Activity: > > - New Members > 3 > - New Photos > 4 > > Visit Your Group > [image: Yahoo! Groups] > Switch to: Text-Only, > Daily Digest=95 > Unsubscribe=95 Terms > of Use > . > > __,_._,___ > > --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk https://sites.google.com/site/sub9khz/ http://qss2.blogspot.com/ http://www.youtube.com/user/G3XBM --0021cc020862723ab604d46d0824 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable
Robert,

3C90 42mm diameter toroids (and = a range of others) are available on-line from Farnell if this helps

=
73s
Roger G3XBM


=
On 29 January 2013 11:28, mal hamilton <g3kevmal@talktalk.net><= /span> wrote:
=A0
----- Original Message -----
From:=20 mal=20 hamilton
Sent: Tuesday, January 29, 2013 11:= 22=20 AM
Subject: Re: [rsgb_lf_group] Impeda= nce=20 transformation on 136 kHz - advice needed

PS
=A0
Robert
An audio amp is not the best method and ineffic= ient even=20 at 137 Khz.
A better approach is=A0a=A0purpose built amplif= ier=20 with a couple of FETS class D or E. There is plenty of info available abo= ut=20 building such amplifiers
=A0
=A0
----- Original Message -----
Sent: Tuesday, January 29, 2013 1= 1:19=20 AM
Subject: Re: [rsgb_lf_group] Impe= dance=20 transformation on 136 kHz - advice needed

Robert
Use a capacitor of around 10 uF in series wit= h the amp=20 output then a 4 to 50 ohm transformer.
Old=A0tv =A0LOPT are suitable or material=20 similar to 3C9 material.
Prim turns around 8 and=A0Sec 28 turns. This = is a=20 rough guide to get started
=A0
de mal/g3kev
=A0
----- Original Message -----
From:=20 robert_la4ana
Sent: Tuesday, January 29, 2013= 9:51=20 AM
Subject: [rsgb_lf_group] Impeda= nce=20 transformation on 136 kHz - advice needed

=A0=20


Hi Group,

As I am planning to use an audio amplifier as= a PA=20 on 136 kHz, I need to
transform the amplifier output (100 Watt at = 4-8=20 Ohm) to 50 Ohm to match
it to the coax cable to the antenna, possi= bly=20 with a 50 Ohm low-pass
filter in between. Not much information is= =20 available on the Internet
about such a specific configuration. I a= m=20 fond of capacitor impedance
transformation, which I use with succe= ss=20 for matching and tuning my loop
antenna on 475 kHz. Could I employ= the=20 same concept to step up impedance
from 4 Ohm to 50 Ohm at the outp= ut of=20 my audio amplifier?

I have also looked into using ferrite toro= ids=20 as transformers but the
sheer amount of information on this subjec= t,=20 often incomplete and
contradictory, is confusing me. It looks like= many=20 are using "3C90" as a
core material, but this type of co= re seems=20 difficult to acquire - at
least for me here in Norway. I understan= d=20 that "type 77" material could
also be used and this one = is easier to=20 get by. If I would opt for an
FT140-77 core, would this be suitabl= e as=20 a transformer toroid for 100
Watt on 136 kHz or would I need a big= ger=20 one? And how many primary and
secondary turns would such a tranfor= mer=20 need to step up from 4-8 Ohm to
50 Ohm?

I would be very gra= teful=20 for some input on this subject before I start
ordering (the wrong)= =20 components.

73 de Robert,

LA4ANA

__._,_.___
Recent=20 Activity:=20
.

__,_._,___



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