Return-Path: Received: from rly-mc05.mx.aol.com (rly-mc05.mail.aol.com [172.21.164.89]) by air-mc02.mail.aol.com (v125.7) with ESMTP id MAILINMC024-d714adb2ae9187; Sun, 18 Oct 2009 10:49:26 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-mc05.mx.aol.com (v125.7) with ESMTP id MAILRELAYINMC051-d714adb2ae9187; Sun, 18 Oct 2009 10:49:15 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1MzX3a-00034s-NK for rs_out_1@blacksheep.org; Sun, 18 Oct 2009 15:48:26 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1MzX3a-00034j-59 for rsgb_lf_group@blacksheep.org; Sun, 18 Oct 2009 15:48:26 +0100 Received: from smtp6.freeserve.com ([193.252.22.191]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1MzX20-0003kd-Sk for rsgb_lf_group@blacksheep.org; Sun, 18 Oct 2009 15:46:49 +0100 Received: from me-wanadoo.net (localhost [127.0.0.1]) by mwinf3619.me.freeserve.com (SMTP Server) with ESMTP id A94C77000082 for ; Sun, 18 Oct 2009 16:48:08 +0200 (CEST) Received: from me-wanadoo.net (localhost [127.0.0.1]) by mwinf3619.me.freeserve.com (SMTP Server) with ESMTP id 9BC877000084 for ; Sun, 18 Oct 2009 16:48:08 +0200 (CEST) Received: from AGB (unknown [91.109.37.156]) by mwinf3619.me.freeserve.com (SMTP Server) with SMTP id 0FB1A7000082 for ; Sun, 18 Oct 2009 16:48:06 +0200 (CEST) X-ME-UUID: 20091018144806643.0FB1A7000082@mwinf3619.me.freeserve.com Message-ID: <59818006922245E9A7BEB2E7D9165B23@AGB> From: "Graham" To: References: In-Reply-To: Date: Sun, 18 Oct 2009 15:47:55 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8089.726 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8089.726 X-Karma: unknown: X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: AF Amps at 136 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0080_01CA500A.5BC67BF0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,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_0080_01CA500A.5BC67BF0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Chris=20 Had a look around Wikipedia , re phase , -3 db , margins , that sort= of thing ..as for removing bits ... would not be the first person= to run into allsorts of problems getting a (137k ) amp to run on= 500 'with' half the bits chopped out ..and still zapp the out put= devices ... easier to agree with MAL =20 (apart from the class d/e bit that is I think there is still a lot = of un-known's /gray noise etc associated with the concept .. article= s like this seem to address the 'un spoken' > http://www.qsl.net/wm= 5z/qex199907.pdf < the subject of heat dissipation in magnetic's hover= s in the background as well for these amplifiers)=20 G ..=20 From: Chris=20 Sent: Sunday, October 18, 2009 2:13 PM To: RSGB LF Group=20 Subject: LF: AF Amps at 136 Hi All, Just started constructing TX for 136kHz, noticed Maplin do a Velleman= audio PA kit that is rated at 200W (100W RMS into 4R). OK there's no= mains transformer or heat sink, but reckon it's good value at =A314.9= 9. Point is the specs also say the minus 3db frequency response is 3Hz= / 200kHz. The RSGB books 'LF Today' refer to using audio amps as PAs at 136 with= 'a few modifications'. Does anybody know where these modifications ar= e documented? I guess there's nothing major, reduce a few cap values?= Remove Zobel Network etc.?? If anyone has experience with this approa= ch I would appreciate some hints. Thanks. Chris, G4AYT, Whitstable. ----------------------------------------------------------------------= ---------- No virus found in this incoming message. Checked by AVG - www.avg.com=20 Version: 8.5.422 / Virus Database: 270.14.20/2444 - Release Date: 10/1= 8/09 09:04:00 ------=_NextPart_000_0080_01CA500A.5BC67BF0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Chris
 
Had a look around Wikipedia , re = ; phase ,=20 -3 db , margins , that sort of thing ..as for  removing bits ...&= nbsp;would=20 not be the  first person to  run into allsorts of  prob= lems=20 getting a  (137k )  amp to  run on 500  'with' hal= f the bits=20 chopped out ..and  still  zapp the  out put devices=20 ...  easier to agree with= =20  MAL  
 
(apart from the class  d/e bit= that is I think=20 there is still a lot  of un-known's /gray noise etc associat= ed with=20 the  concept .. articles like this  seem to address the = ; 'un=20 spoken' >  http://www.qsl.net/wm5z/qex199907.pdf <=20 the subject of heat dissipation in magnetic's hovers in the background= as well=20 for these amplifiers)
 
G ..

From: Chris
Sent: Sunday, October 18, 2009 2:13 PM
Subject: LF: AF Amps at 136

Hi All,
Just started constructing TX for 136k= Hz, noticed=20 Maplin do a Velleman audio PA kit that is rated at 200W (100W RMS into= 4R). OK=20 there's no mains transformer or heat sink, but reckon it's good value= at =A314.99.=20 Point is the specs also say the minus 3db frequency response is= 3Hz /=20 200kHz.
The RSGB books 'LF Today' refer to us= ing audio amps=20 as PAs at 136 with 'a few modifications'. Does anybody know where thes= e=20 modifications are documented? I guess there's nothing major, reduce a= few cap=20 values? Remove Zobel Network etc.?? If anyone has experience with this= approach=20 I would appreciate some hints. Thanks.
Chris, G4AYT, Whitstable.


No virus found in this incoming message.
Checked by AVG= -=20 www.avg.com
Version: 8.5.422 / Virus Database: 270.14.20/2444 - Re= lease=20 Date: 10/18/09 09:04:00
------=_NextPart_000_0080_01CA500A.5BC67BF0--