Return-Path: Received: (qmail 54582 invoked from network); 22 Jan 2004 07:25:24 -0000 Received: from unknown (HELO ptb-mxscan02.plus.net) (212.159.14.236) by ptb-mailstore02.plus.net with SMTP; 22 Jan 2004 07:25:24 -0000 Received: (qmail 81278 invoked from network); 22 Jan 2004 07:25:24 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Priority: 3 X-MSMail-Priority: Normal X-Spam-detection-level: 11 Received: from ptb-mxcore02.plus.net (212.159.14.216) by ptb-mxscan02.plus.net with SMTP; 22 Jan 2004 07:25:23 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1AjZDO-000L1z-WB for dave@picks.force9.co.uk; Thu, 22 Jan 2004 07:25:23 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1AjZCp-0001LI-PY for rs_out@blacksheep.org; Thu, 22 Jan 2004 07:24:47 +0000 Received: from [192.108.125.11] (helo=alpha.sbs.sk) by post.thorcom.com with esmtp (Exim 4.14) id 1AjZCp-0001L9-0n for rsgb_lf_group@blacksheep.org; Thu, 22 Jan 2004 07:24:47 +0000 Received: from hermes.sbs.sk (hermes.sbs.sk [192.108.125.51]) by alpha.sbs.sk (Postfix) with ESMTP id 66E6B3ECB for ; Thu, 22 Jan 2004 08:24:44 +0100 (CET) X-Fake-Domain: btss005a.sbs.sk Received: from btss005a.sbs.sk (btss.swh.sk [139.24.136.180]) by hermes.sbs.sk (8.12.6/8.12.6/SuSE Linux 0.6) with ESMTP id i0M7OiCc005166 for ; Thu, 22 Jan 2004 08:24:44 +0100 Received: by btss.siemens-pse.sk with Internet Mail Service (5.5.2653.19) id ; Thu, 22 Jan 2004 08:24:43 +0100 X-Bad-Message-ID: no DNS (btss.siemens-pse.sk) Message-ID: From: "Gasparik Richard" To: rsgb_lf_group@blacksheep.org Date: Thu, 22 Jan 2004 08:24:41 +0100 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Subject: LF: RE: TDA2030 amplifier by OM2TW Content-Type: text/html; charset=windows-1252 X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.6 required=5.0 tests=HTML_40_50,HTML_FONTCOLOR_BLUE,HTML_MESSAGE,MAILTO_TO_SPAM_ADDR autolearn=no version=2.60 X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SPAMFiltered: yes X-Spam-Rating: 2 Content-transfer-encoding: 8bit

Hi Dick,

L3/L4 is a step up transformer. Normaly the TDA 2030 have 4-8 Ohm output impedance. You must look for an toroid with very high permeability (2000 and more) and make an L3:L4 = 1:3 transformer (in my case 11 turns primary:33turns secondary) whitch is 1:9 impedance transformer.

73 de Rich OM2TW

-----Original Message-----
From: Dick [mailto:knaap159@zonnet.nl]
Sent: Wednesday, January 21, 2004 8:35 PM
To: rsgb_lf_group@blacksheep.org
Subject: LF: TDA2030 amplifier by OM2TW

Hello all,

As I haven't OM2TW's emailadress right now, I'll ask here.

I found an pdf.drawing of the TDA2030 amplifier giving 5Watts or so on 136kHz.

however, at hte output stage there are two coils L3/L4 (ouput transformer) with no

further details mentioned.

Can anyone help me with detailed info about the value/or how to construct these coils?

Also some uncertainty about C21 and C22, are they elco's or normal C's????

73 Dick, pa4vhf

(now probably first try to create QRP in an easy way.......)