Return-Path: Received: from mtain-dh05.r1000.mx.aol.com (mtain-dh05.r1000.mx.aol.com [172.29.65.25]) by air-mf05.mail.aol.com (v126.13) with ESMTP id MAILINMF054-8bec4b6195a7391; Thu, 28 Jan 2010 08:48:23 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dh05.r1000.mx.aol.com (Internet Inbound) with ESMTP id A26773800008F; Thu, 28 Jan 2010 08:48:21 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NaUiL-0002UZ-CT for rs_out_1@blacksheep.org; Thu, 28 Jan 2010 13:47:17 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NaUiK-0002UQ-Sw for rsgb_lf_group@blacksheep.org; Thu, 28 Jan 2010 13:47:16 +0000 Received: from mail-fx0-f209.google.com ([209.85.220.209]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NaUiI-0006hv-3T for rsgb_lf_group@blacksheep.org; Thu, 28 Jan 2010 13:47:16 +0000 Received: by fxm1 with SMTP id 1so756817fxm.4 for ; Thu, 28 Jan 2010 05:47:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=0U0piFyaPRCYxJoRKNdUc/mV2BUrCEFZSiTqvJP7IkU=; b=rr56b697Sn3SPIGok2KreqkQ4Z4efHKV2+M7kIQLHX5blZ09E/9FcIrU85QmyUB6oC d7mHk7NRQEYKJgOeo8XU05QrVybuzgLPp0xOZq/eoekEemZtKhzXsXFz7iud7hpI7rwY QEJL0AwDx2vINEm1DgxRgIMoWdymPKM0JlaFo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=a5ZRxbI2z3prRMqOOWRKUmla1B4fVaXu2CDJ8HhU/meiHr9YGFJcEt8718lC7D7g9E EfShxTTBJbodRNDfqtj5wA0yJJdx5drjalBIgvE8iO0fjkTUuARDJtu2i1uZ6fhgc910 6v3rIZY7318kU5y9I0G8IiEkeQ3wYydNaPi9o= MIME-Version: 1.0 Received: by 10.239.187.66 with SMTP id k2mr1206023hbh.213.1264686427000; Thu, 28 Jan 2010 05:47:07 -0800 (PST) In-Reply-To: <45636.72585.qm@web86405.mail.ird.yahoo.com> References: <45636.72585.qm@web86405.mail.ird.yahoo.com> Date: Thu, 28 Jan 2010 13:47:06 +0000 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.9 (/) X-Spam-Report: autolearn=disabled,HTML_10_20=0.945,HTML_MESSAGE=0.001 Subject: LF: Fwd: 500kHz JT4A Content-Type: multipart/alternative; boundary=001636498b653bcfb6047e39c18a 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=HTML_MESSAGE 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: 3039ac1d41194b6195a50880 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --001636498b653bcfb6047e39c18a Content-Type: text/plain; charset=ISO-8859-1 Dear Andy, I tried to send this to the LF reflector, but I am away from home at the moment, and it does not seem to want to accept mail from me - perhaps you could forward it... Dear Rik, Andy, I have been using a push-pull class D PA in my "EER transverter" for various FSK (and linear) modes over the last year or so. To get a symmetrical square-wave drive from the low-level (basically sinusoidal) 500k input, the input signal is squared up by a limiting amplifier, to a TTL level, then drive to one gate is simply inverted. To get a 50/50 square wave drive, it is important that the limiter has symmetrical limiting thresholds - the circuit I used can be seen in the EER Transverter v3 article on the UK_500kHz group files download page at http://groups.google.co.uk/group/uk500khz/files. It is also important that the input to the limiter has a symmetrical waveform - but this is easily achieved by simple band-pass filtering, a single tuned circuit with a loaded Q of, say, 5 will produce a nice sine wave from a fairly horrible input waveform. Cheers, Jim Moritz 73 de M0BMU --- On Wed, 27/1/10, Andy Talbot wrote: > From: Andy Talbot > Subject: Re: LF: RE: 500 kHz JT4A > To: rsgb_lf_group@blacksheep.org > Date: Wednesday, 27 January, 2010, 21:56 > 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. > > --001636498b653bcfb6047e39c18a Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

Dear Andy,

I tried to send this to= the LF reflector, but I am away from home at the moment, and it does not= seem to want to accept mail from me - perhaps you could forward it...
=
Dear Rik, Andy,

I have been using a push-pull class D PA in my "EER transverter&q= uot; for various FSK (and linear) modes over the last year or so. To get= a symmetrical square-wave drive from the low-level (basically sinusoidal)= 500k input, the input signal is squared up by a limiting amplifier, to a= TTL level, then drive to one gate is simply inverted. To get a 50/50 squa= re wave drive, it is important that the limiter has symmetrical limiting= thresholds - the circuit I used can be seen in the EER Transverter v3 art= icle on the UK_500kHz group files download page at http://groups.googl= e.co.uk/group/uk500khz/files. It is also important that the input to= the limiter has a symmetrical waveform - but this is easily achieved by= simple band-pass filtering, a single tuned circuit with a loaded Q of, sa= y, 5 will produce a nice sine wave from a fairly horrible input waveform.<= br>
Cheers, Jim Moritz
73 de M0BMU

--- On Wed, 27/1/10, Andy Tal= bot <andy.g4jnt@googlemail= .com> wrote:

> From: Andy Talbot <andy.g4jnt@googlemail.com>
> Subject: Re: LF: RE: 500 kHz JT4A
> To: rsgb_lf_group@blacksheep.org
> Date: We= dnesday, 27 January, 2010, 21:56
> I was looking at driving push-pul= l
> transmitters from fundamental drive signals quite
> recently.= =A0=A0=A0
>=A0
> How about a frequency doubler?=A0 =A0 The out= put
> doesn't have to have 1:1 mark-space ratio as it only
&g= t; clocks a flip-flop.=A0=A0=A0And simple doubler can consists of
> a delay line (CR network with around 0.5us time constant)
> fol= lowed by a squarer to give a resulting waveform shifted
> in phase= from the 500kHz drive signal.=A0 Then apply this
> one,=A0 along wi= th 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.
>
>=A0
<= br>


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