Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-me06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 45D41380000A3; Fri, 6 Jul 2012 06:50:45 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Sn66g-0005Sv-VO for rs_out_1@blacksheep.org; Fri, 06 Jul 2012 11:49:50 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Sn66g-0005Sm-84 for rsgb_lf_group@blacksheep.org; Fri, 06 Jul 2012 11:49:50 +0100 Received: from nm5.bullet.mail.ird.yahoo.com ([77.238.189.62]) by relay1.thorcom.net with smtp (Exim 4.77) (envelope-from ) id 1Sn66d-00034w-F3 for rsgb_lf_group@blacksheep.org; Fri, 06 Jul 2012 11:49:49 +0100 Received: from [77.238.189.233] by nm5.bullet.mail.ird.yahoo.com with NNFMP; 06 Jul 2012 10:49:46 -0000 Received: from [212.82.108.224] by tm14.bullet.mail.ird.yahoo.com with NNFMP; 06 Jul 2012 10:49:46 -0000 Received: from [127.0.0.1] by omp1001.bt.mail.ird.yahoo.com with NNFMP; 06 Jul 2012 10:49:46 -0000 X-DKIM-Result: Domain=btopenworld.com Result=Signature OK X-Yahoo-Newman-Id: 659216.43153.bm@omp1001.bt.mail.ird.yahoo.com Received: (qmail 4701 invoked from network); 6 Jul 2012 10:49:46 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btopenworld.com; h=DKIM-Signature:X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:From:To:Subject:Date:Message-ID:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:In-Reply-To:X-MimeOLE:Importance; b=cMznlkUdHug4jJco9nryUH7s7dvHsZLsT+VQRiA5jIRZuOJbXJJseBNT7EsNzFEJ6R8+Bb2Zz86qD19liAeOdOw9c+Bjy1Vke/awMFqwWzfn84grR1CIODVuwCLUVoKaPdCt/0pr/oRcDSIpJeUEsS5cC7oQSJEl2mh8EzYW12s= ; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btopenworld.com; s=s1024; t=1341571786; bh=kDf9AjQ3PQ8eKn+mKgVY5oq5WtlyquYodnaYvkOiFg8=; h=X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:From:To:Subject:Date:Message-ID:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:In-Reply-To:X-MimeOLE:Importance; b=lAnGjc5yFdFGOfJNj/Rj7/yL2ujpc7smeFqMULKDowavo7BZa4BKAhZy2wM3hetZWB0Q1CkdyyWonuHTDxvOyCJ+rOL+871tZhjbqaHb6JNddX8henh1k0Zi5Om855PXQK2K1cnh16Y/BXSx6G/FoBdIJ0inJwribChW5w369fs= X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: .iOXe14VM1lRMehfWPJqE6dyAE.lycpj1L0b4OuMrav8Q.c lxOuzlHKkB6jxY9NLWg0LRQc_r3uEXHPGFjAi1f6h4oTDleshC9W6Mbw45iw Qcr6kGs0Ya_gpkFavC11j8gSSNm5pTaBdm2R18m5UhteUIKJhjGOyYksbo3G CPrTYFRYR0fluV24pP0_dhrsOrI79OR585nu3_IUufgVbRi_IeJNviufrwSn l3ey4gWQWvhXzUjTmU8FijNajzXHQypOtbOYXhbqgZL7WQMUywxsWHbdh7R8 aM4L5GXQMDTr0X7mi6SsIbCInkHWFMDUDpIIY2bsR2JCgOjU4SWRgL4bVYPo FpY_bz9jkh.KLq5PwQLQLnFVEkWHFfBR.AZszyQlwba5HT2lzN0q6QonrEAG gtkelyyXxA3LN9DTIpOqMrTtDzXVZxvOPv1aEye30Nysqlhevc8_mYdJT2rL 5XAhg4CiJLlu6IaNjBocVmZPMYtZN55g2cINCP5OxA3H.t4vkSODo5gn140c vecVXAQEN.ib9Uk4FuJ7nezEVu10Y56p7vnZvP.2rCi8YRy0gBwPbiY2xMJU G.w-- X-Yahoo-SMTP: c8dPawiswBBxxmjSAvmKGJq150SoSoD6d8MTABSG9Now_xuQLZ9d Received: from taurids (ganymede444@81.154.12.235 with login) by smtp824.mail.ukl.yahoo.com with SMTP; 06 Jul 2012 03:49:45 -0700 PDT From: "Dave G3WCB." To: Date: Fri, 6 Jul 2012 11:48:53 +0100 Message-ID: MIME-Version: 1.0 X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) In-Reply-To: <1341570473.13429.YahooMailNeo@web171601.mail.ir2.yahoo.com> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Importance: Normal X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hi, Group, Pete, I never bothered with the "Tempatrimmer", although if you come across one at a junk-sale it's probably worth picking it up. You can fine-trim the oscillator temperature response by selecting between positive temperature-coeffecient or NTC capacitors. Shouldn't be necessary for work on MF. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [77.238.189.62 listed in list.dnswl.org] 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid 0.0 UNPARSEABLE_RELAY Informational: message has unparseable relay lines X-Scan-Signature: 96e7ff1ec9673d9aa57a617c94da6cf3 Subject: LF: Analog oscillators [Vackar] Content-Type: multipart/alternative; boundary="----=_NextPart_000_0036_01CD5B6D.5158F640" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.5 required=5.0 tests=FROM_ENDS_IN_NUMS,HTML_20_30, HTML_FONTCOLOR_BLUE,HTML_MESSAGE,MAILTO_TO_SPAM_ADDR 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-SCORE: 0:2:407831392:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d308.1 ; domain : btopenworld.com DKIM : fail x-aol-sid: 3039ac1d608e4ff6c3051c45 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_0036_01CD5B6D.5158F640 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Hi, Group, Pete, I never bothered with the "Tempatrimmer", although if you come across one at a junk-sale it's probably worth picking it up. You can fine-trim the oscillator temperature response by selecting between positive temperature-coeffecient or NTC capacitors. Shouldn't be necessary for work on MF. The tips about mechanical stability, etc, are still relevant today, even for PLL and varactor-tuned designs. 73, Dave G3WCB IO91RM -----Original Message----- From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of M0FMT Sent: 06 July 2012 11:28 To: rsgb_lf_group@blacksheep.org Subject: Re: LF: RE: Analog oscillators [Vackar] Hi Stefan and group Look carefully at the circuit for the VACKAR VFO which has been hawked around in the RSGB Handbook for years. Note in the bottom LH corner of the schematic Oxley "TEMPATRIMMER" without this piece of "Unobtainium" its like any other free running osc. They are not made now but someone is selling old bits for about 35 dollars US at http://www.bmius.com/p-9560-oxley-xxx-tempatrimmer.aspx That sort of price will get you a modern DDS with all the facilities but IMHE they are susceptible to RF possibly more so at LF because the antenna tuner is big and in my case not shielded, so "RF in the Shack" issues. Beating two xtals works for me but I have never checked the stability seriously. It works OK for 500kc/s because these are standard xtals 60P ea (probably of dubious stability) 6.000 and 6.500 and are pulled to a max of four (4)kc/s. 477 is more difficult these wont be "off the shelf" items. The Si57x is another solution there are "VFO" applications using it. Or PIC control with say a range of closely set spot QRGs. Look in the archive of the Softrock Yahoo group for the design and software details of the "Xtall" LO. 73 es GL Pete M0FMT IO91UX From: Dave G3WCB. To: rsgb_lf_group@blacksheep.org Sent: Friday, 6 July 2012, 8:43 Subject: LF: RE: Analog oscillators [Vackar] Hi, Stefan, LF, I suggest you consider the Vackar oscillator. There is a very good FET/transistor design by G3PDM which you can reach by following the link below. It's also important to consider the mechanical design of the oscillator and its enclosure. I think you'll be disappointed with the results of your construction - the tinplate box will be quite "flimsy", and the arrangement with the tuning capacitor in the lid means that you will have quite long unsupported wires connecting the frequency determining components. I suggest that you start with a more rigid metal box, say an aluminium die-cast box, and mount all the rf components, including the coil, close together and as rigidly as possible. In the past I have used ceramic stand-off pillars, but strips of fibreglass PC board material soldered to M3 screws works just as well. For the coil, use a styrene or ceramic former with a dust-iron (not ferrite) tuning slug. Avoid toroids for the oscillator coil, if possible. The G3PDM article has some useful information on mechanical constuction. There was a load of work done by hams and professionals on transistor oscillators in the 1970s and 1980s, but it's been largely forgotten with the introduction of PLLs and DDSs. It just needs to be re-discovered! Good luck! 73, Dave G3WCB IO91RM http://www.qsl.net/va3diw/vackar.html > > The NE602 works very well as oscillator and delivers a clean and low > noise signal. > One of the main problem in building VFO's is the mechanical design. > It can be done, but it is not trivial when you use a tuning capacitor > and gearbox. > Mechanical rigidity and freedom from micropfonics requires a solid > enclosure which with the gearbox need to be mounted on the frontpanel, > rather than on the chassis. > > As the frequency range is small, it will be mechanically much easier > to use varactor tuning in conjunction with a ten turn potmeter. I have > been there and done it all. > I have build a 40 m receiver with varactor tuning and it is rock stable. > > Building VFO's is fun! > > 73, > Roelof, pa0rdt > ------=_NextPart_000_0036_01CD5B6D.5158F640 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi,=20 Group, Pete,
 
I=20 never bothered with the "Tempatrimmer", although if you come across one = at a=20 junk-sale it's probably worth picking it up. You can fine-trim the = oscillator=20 temperature response by selecting between positive = temperature-coeffecient or=20 NTC capacitors. Shouldn't be necessary for work=20 on MF.
 
The=20 tips about mechanical stability, etc, are still relevant today, even for = PLL and=20 varactor-tuned designs.
 
73,=20 Dave G3WCB IO91RM 
-----Original Message-----
From:=20 owner-rsgb_lf_group@blacksheep.org=20 [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of=20 M0FMT
Sent: 06 July 2012 11:28
To:=20 rsgb_lf_group@blacksheep.org
Subject: Re: LF: RE: Analog = oscillators=20 [Vackar]

Hi Stefan and group
 
Look carefully at the circuit for the VACKAR VFO which has = been=20 hawked around in the RSGB Handbook for years. Note in the bottom LH = corner of=20 the schematic Oxley "TEMPATRIMMER" without this piece of "Unobtainium" = its=20 like any other free running osc.
 
They are not made now but someone is selling old bits for = about 35=20 dollars US at http://w= ww.bmius.com/p-9560-oxley-xxx-tempatrimmer.aspx =20
 
That sort of price will get you a modern DDS with all the = facilities but IMHE they are susceptible to RF possibly more = so at LF=20 because the antenna tuner is big and in my case not shielded, so "RF in the Shack"=20 issues.
 
Beating two xtals works for me but I have never checked the = stability seriously. It works OK for 500kc/s because these are = standard xtals=20 60P ea (probably of dubious stability) 6.000 and 6.500 and are pulled = to a max=20 of four (4)kc/s. 477 is more difficult these wont be "off the shelf" items.
The Si57x is another solution there are "VFO" applications using = it. Or=20 PIC control with say a range of closely set spot QRGs. Look in the = archive of=20 the Softrock Yahoo group for the design and software details of the "Xtall" LO.
73 es GL Pete M0FMT IO91UX
From:=20 Dave G3WCB. <ganymede444@btopenworld.com>
To: = rsgb_lf_group@blacksheep.org=20
Sent: Friday, 6 = July 2012,=20 8:43
Subject: LF: = RE:=20 Analog oscillators [Vackar]

Hi, Stefan, = LF,

I=20 suggest you consider the Vackar oscillator. There is a very=20 good
FET/transistor design by G3PDM which you can reach by = following the=20 link
below.

It's also important to consider the mechanical = design=20 of the oscillator and
its enclosure. I think you'll be = disappointed with=20 the results of your
construction - the tinplate box will be quite = "flimsy", and the arrangement
with the tuning capacitor in the = lid means=20 that you will have quite long
unsupported wires connecting the = frequency=20 determining components.

I suggest that you start with a more = rigid=20 metal box, say an aluminium
die-cast box, and mount all the rf=20 components, including the coil, close
together and as rigidly as=20 possible. In the past I have used ceramic
stand-off pillars, but = strips=20 of fibreglass PC board material soldered to M3
screws works just = as well.=20 For the coil, use a styrene or ceramic former
with a dust-iron = (not=20 ferrite) tuning slug. Avoid toroids for the oscillator
coil, if=20 possible.

The G3PDM article has some useful information on = mechanical=20 constuction.
There was a load of work done by hams and = professionals on=20 transistor
oscillators in the 1970s and 1980s, but it's been = largely=20 forgotten with the
introduction of PLLs and DDSs. It just needs = to be=20 re-discovered!

Good luck!

73, Dave G3WCB = IO91RM

http://www.qsl.net/va3diw/vackar.html



= >
>=20 The NE602 works very well as oscillator and delivers a clean and = low
>=20 noise signal.
> One of the main problem in building VFO's is = the=20 mechanical design.
> It can be done, but it is not trivial = when you=20 use a tuning capacitor
> and gearbox.
> Mechanical = rigidity and=20 freedom from micropfonics requires a solid
> enclosure which = with the=20 gearbox need to be mounted on the frontpanel,
> rather than on = the=20 chassis.
>
> As the frequency range is small, it will be = mechanically much easier
> to use varactor tuning in = conjunction with=20 a ten turn potmeter. I have
> been there and done it = all.
> I=20 have build a 40 m receiver with varactor tuning and it is rock=20 stable.
>
> Building VFO's is fun!
>
> = 73,
>=20 Roelof,=20 pa0rdt
>


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