Return-Path: Received: from mtain-mj01.r1000.mx.aol.com (mtain-mj01.r1000.mail.aol.com [172.21.164.85]) by air-db07.mail.aol.com (v129.4) with ESMTP id MAILINDB072-86214cd710784c; Sun, 07 Nov 2010 15:47:53 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mj01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 6233F38000094; Sun, 7 Nov 2010 15:47:50 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PFC7w-0007tx-Vn for rs_out_1@blacksheep.org; Sun, 07 Nov 2010 20:46:12 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PFC7w-0007to-8v for rsgb_lf_group@blacksheep.org; Sun, 07 Nov 2010 20:46:12 +0000 Received: from mail-iw0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PFC7t-0007OI-DY for rsgb_lf_group@blacksheep.org; Sun, 07 Nov 2010 20:46:12 +0000 Received: by iwn38 with SMTP id 38so4758064iwn.16 for ; Sun, 07 Nov 2010 12:46:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=lMWUln+xIAFj2W1faOrJr1mHIJ/Yasrq8lLpXXSs570=; b=lO2blRTlm9ivjvc9t9vWCFQXOT7OoAnLO+RxsLRsLRC6zccpTcT8eWZ0TKAKlRs2ob Zcxic/7IuijTbxnW4kMh6ppTrihdbQ5l9b1V8QcR9/2EWeMQ3AZgDwYrr3NHxJcryCeY iQo19pVW9ERkFsV20ep0LqYU57KOqQmAq9uU8= 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=lpo61XFD8LdpSB2FeYS3oPQRripIlWS5s1EA/Wrc1mlBY1BBM330KJ0YrazbYrz470 735389Bvx1+tR3Mf0TeDSxaZA5ngJNZZzpG7nd3pQgvXcV9T1rev9dqQtbM7/7nyLfXa LeD9zYUhPHkcZ/nWxPxfrjITFsm1283dy2Qgc= MIME-Version: 1.0 Received: by 10.42.221.137 with SMTP id ic9mr2863617icb.151.1289162766772; Sun, 07 Nov 2010 12:46:06 -0800 (PST) Received: by 10.231.79.69 with HTTP; Sun, 7 Nov 2010 12:46:06 -0800 (PST) In-Reply-To: <4CD6FF00.9090406@telia.com> References: <000c01cb7da9$23b1a1e0$8d01a8c0@JAYDELL> <4CD6FF00.9090406@telia.com> Date: Sun, 7 Nov 2010 20:46:06 +0000 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: exciter for 137 and 500 kHz Content-Type: multipart/alternative; boundary=20cf30434752c56b7604947c984f 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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d287.2 ; domain : googlemail.com DKIM : pass x-aol-sid: 3039400c89a24cd71075709f X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --20cf30434752c56b7604947c984f Content-Type: text/plain; charset=ISO-8859-1 That's a neat bit of software! But I've noticed in all the all-pass design procedures, there are choices of optimising, Monte Carloe-ing, adjusting and tuning the RC part of the networks. But none seem to take into account the effect of mismatch of the nominally matched pair of resistors around each opamp. Or of residual amplitude mismatching. But it does seem that if you are prepared to spend the time getting all the Rs and Cs within a micro percent of the correct values, then apply the same effort to amplitude and phase matching the channels, a quite phenomenal performance wrt. sideband suppression is theoretically possible. But I guess in any practical scenario, most constructors will tweak for an acceptable performance and leave it alone. For upconverting at LF, we're only interested in narrow band signals - the entire WSPR segment is only 200kHz wide - and a simple 2 stage (one opamp in each of I and Q) is adequate. In that case a pair of preset or variable resistors can be tweaked quite quickly. 40 - 50dB supression seems almost guaranteed over a 100Hz using a predictable mixers like fast CMOS switches, with a comparable level of carrier suppression. I've built two now, one with FST3125 and a balanced output transformer, and one with a dual quad switch, FST3257. The latter gives somewhat better performance, but is slightly more complex. Andy www.g4jnt.com On 7 November 2010 19:33, Johan H. Bodin wrote: > Andy, > > here's another nice program for all-pass I/Q filter design: > > http://www.tonnesoftware.com/quad.html > > 73 > Johan SM6LKM > > ---- > > Andy Talbot wrote 2010-11-06 14:59: > > Very Interesting. > > Where did you find the design data for the allpass network? I've only > been > > able to find the values for up to 3+3 allpass stages. > > > > Mind you, at that number of chips a DSPic begins to look attractive. > > > > > > Andy > > www.g4jnt.com > > > > > > On 6 November 2010 11:52, jrusgrove@comcast.net>> > > wrote: > > > > Nothing earth shattering ... another way to skin the cat. The 137 and > 500 > > kHz units have been in use for a few years ... just now getting > around to > > the write up. > > > > http://www.w1vd.com/137-500Phasingexciter.html > > > > Jay W1VD WD2XNS WE2XGR/2 > > > > > > --20cf30434752c56b7604947c984f Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
That's a neat bit of software!
=A0
But I've noticed in all the all-pass design procedures,=A0there= are=A0choices of=A0optimising, Monte Carloe-ing, adjusting and tuning the= RC=A0 part of the networks.=A0 But none seem to take into account the eff= ect of mismatch=A0of the nominally matched pair of resistors around each= opamp.=A0=A0 Or of residual amplitude mismatching.
=A0
But it does seem that if you are prepared to spend the time getting= all the=A0Rs and Cs=A0within a micro percent of the correct values, then= apply the same effort to amplitude and phase matching the channels, a qui= te phenomenal performance wrt. sideband suppression is theoretically possi= ble.
=A0
But I guess in any practical scenario,=A0most constructors will tweak= for an acceptable performance and leave it alone.=A0=A0 For upconverting= at LF, we're only interested in narrow band signals - the entire WSPR= =A0segment is only 200kHz wide - and a simple 2 stage (one opamp in each= of I and Q) is adequate.=A0=A0In that case a pair of preset or variable= resistors can be tweaked quite quickly.=A0=A0 40 - 50dB supression=A0seem= s almost guaranteed over a 100Hz using a predictable mixers like fast CMOS= switches, with a comparable level of carrier suppression.=A0 I've bui= lt two now, one with FST3125 and a balanced output transformer, =A0and one= with a dual quad switch, FST3257.=A0 The latter gives somewhat better per= formance, but is slightly more complex.
=A0
On 7 November 2010 19:33, Johan H. Bodin <jh.bodin@telia.com<= /a>> wrote:
Andy,

here's anothe= r nice program for all-pass I/Q filter design:

=A0http://www.tonnesoftwa= re.com/quad.html

73
Johan SM6LKM

----

Andy Talbot wrote 2010-11-06 14:= 59:
> Very Interesting.
> Where did you find the de= sign data for the allpass network? =A0 I've only been
> able to= find the values for up to 3+3 allpass stages.
>
> Mind you,= at that number of chips a DSPic begins to look attractive.
>
>
> Andy
> www.g4jnt.com <http://www.g4jnt.com>
>
>
> On= 6 November 2010 11:52, <jrusg= rove@comcast.net <mailto:j= rusgrove@comcast.net>>
> wrote:
>
> =A0 =A0 Nothing earth shatte= ring ... another way to skin the cat. The 137 and 500
> =A0 =A0 kHz= units have been in use for a few years ... just now getting around to
= > =A0 =A0 the write up.
>
> =A0 =A0 http://www.w1vd.com/137-500Phasingexciter.html=
>
> =A0 =A0 Jay W1VD =A0WD2XNS =A0WE2XGR/2
>
>

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