Return-Path: Received: from mtain-me12.r1000.mx.aol.com (mtain-me12.r1000.mx.aol.com [172.29.96.148]) by air-df01.mail.aol.com (v126.13) with ESMTP id MAILINDF013-5ee44b614a5819b; Thu, 28 Jan 2010 03:27:04 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-me12.r1000.mx.aol.com (Internet Inbound) with ESMTP id 9EA6F380000B2; Thu, 28 Jan 2010 03:27:02 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NaPhP-0001RC-Sv for rs_out_1@blacksheep.org; Thu, 28 Jan 2010 08:25:59 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NaPhP-0001R3-HX for rsgb_lf_group@blacksheep.org; Thu, 28 Jan 2010 08:25:59 +0000 Received: from pne-smtpout1-sn2.hy.skanova.net ([81.228.8.83]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NaPhN-0003iK-D5 for rsgb_lf_group@blacksheep.org; Thu, 28 Jan 2010 08:25:59 +0000 Received: from [127.0.0.1] (81.235.167.68) by pne-smtpout1-sn2.hy.skanova.net (7.3.140.3) (authenticated as u33233109) id 4B5C66860008FF52 for rsgb_lf_group@blacksheep.org; Thu, 28 Jan 2010 09:25:51 +0100 Message-ID: <4B614A11.6020509@telia.com> Date: Thu, 28 Jan 2010 09:25:53 +0100 From: "Johan H. Bodin" User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <1f0624b91001271133g22391461tfa8dc9a87c8f14d4@mail.gmail.com> <1f0624b91001271303v1eb7094bp659dba8418585e81@mail.gmail.com> In-Reply-To: X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: RE: 500 kHz JT4A Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: 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-aol-global-disposition: G x-aol-sid: 3039ac1d60944b614a5663ac X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) Andy, such a doubler will work but the flip-flop is not a guarantee for a perfect 50/50 square wave in this case. The flip-flop will be clocked by both edges of *one* of the XOR input signals, which one depends on the clock polarity (rising or falling edge) at the flip-flop input so the flip-flop output will have the same duty cycle as one of the XOR input signals. The traditional C.T. transformer will work equally well (or bad). 73 Johan SM6LKM ---- Andy Talbot wrote: > I was looking at driving push-pull transmitters from fundamental drive > signals quite recently. > > How about a frequency doubler? The output doesn't have to have 1:1 > mark-space ratio as it only clocks a flip-flop. And simple doubler can > consists of a delay line (CR network with around 0.5us time constant) > followed by a squarer to give a resulting waveform shifted in phase from > the 500kHz drive signal. Then apply this one, along with the original > to a two input XOR gate whose output will then consists of a 1MHz train > suitable for dividing by 2 for a perfect 1:1 squarewave drive. > > > Andy > www.g4jnt.com