Return-Path: Received: (qmail 65008 invoked from network); 30 May 2004 10:48:23 -0000 Received: from unknown (HELO ptb-mxscan02.plus.net) (212.159.14.236) by ptb-mailstore04.plus.net with SMTP; 30 May 2004 10:48:23 -0000 Received: (qmail 56780 invoked from network); 30 May 2004 10:48:23 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Spam-detection-level: 11 Received: from ptb-mxcore02.plus.net (212.159.14.216) by ptb-mxscan02.plus.net with SMTP; 30 May 2004 10:48:22 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1BUNra-000Ee8-37 for dave@picks.force9.co.uk; Sun, 30 May 2004 10:48:22 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1BUNqT-0006lC-LP for rs_out_1@blacksheep.org; Sun, 30 May 2004 11:47:13 +0100 Received: from [213.232.95.59] (helo=relay.salmark.net) by post.thorcom.com with esmtp (Exim 4.14) id 1BUNqS-0006l3-UX for rsgb_lf_group@blacksheep.org; Sun, 30 May 2004 11:47:13 +0100 Received: from mailfe06.swip.net ([212.247.154.161]) by relay.salmark.net with esmtp (Exim 4.24) id 1BUUOz-0004ou-DX for rsgb_lf_group@blacksheep.org; Sun, 30 May 2004 18:47:17 +0100 X-T2-Posting-ID: 3bgU4LVfFOB/SKpu7D1OzA== Received: from [212.151.12.171] (HELO oemcomputer) by mailfe06.swip.net (CommuniGate Pro SMTP 4.2b4a) with SMTP id 49702365 for rsgb_lf_group@blacksheep.org; Sun, 30 May 2004 12:47:07 +0200 X-Bad-Message-ID: no DNS (oemcomputer) Message-ID: <006e01c44633$7add0cc0$ab0c97d4@oemcomputer> From: "Johan Bodin" To: rsgb_lf_group@blacksheep.org References: Date: Sun, 30 May 2004 10:46:41 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Spam-Score: 0.1 (/) X-Spam-Report: autolearn=no,RCVD_IN_SORBS=0.1 Subject: LF: Re: Audio Amp IC's on 136kHz. Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.0 required=5.0 tests=none 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-PN-SPAMFiltered: yes X-Spam-Rating: 2 Hi David, A switching amplifier with modulated supply should also be able to do the trick. At 15 watts, a single transistor class E amplifier comes to my mind. For example, the modulation can be made by an op-amp and a darlington transistor. If efficiency is an issue, PWM modulation is more elegant but away goes the simplicity... Clint Turner KA7OEI has some nice information on a PIC based PSK-31 beacon TX that uses a class E PA with a linear modulator: http://www.ussc.com/~turner/ 73 Johan SM6LKM > It's been a few years since I looked at Audio Amp IC's on the LF bands, but > I'm now trying to find one that works to some degree at 136kHz. > I need to find an audio IC capable of about 15 Watts as a minimum. > It's for use with a standalone PIC based PSK transmitter that uses the G3PLX > Varicode, I just thought that a good IC would minimise the component count. > Regards > David G0MRF