Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 73D41380000A0; Fri, 6 Jul 2012 06:29:13 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Sn5lW-0005L1-Ey for rs_out_1@blacksheep.org; Fri, 06 Jul 2012 11:27:58 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Sn5lV-0005Ks-Hl for rsgb_lf_group@blacksheep.org; Fri, 06 Jul 2012 11:27:57 +0100 Received: from nm12.bullet.mail.ird.yahoo.com ([77.238.189.65]) by relay1.thorcom.net with smtp (Exim 4.77) (envelope-from ) id 1Sn5lT-0002yr-2K for rsgb_lf_group@blacksheep.org; Fri, 06 Jul 2012 11:27:56 +0100 Received: from [77.238.189.53] by nm12.bullet.mail.ird.yahoo.com with NNFMP; 06 Jul 2012 10:27:54 -0000 Received: from [212.82.108.253] by tm6.bullet.mail.ird.yahoo.com with NNFMP; 06 Jul 2012 10:27:54 -0000 Received: from [127.0.0.1] by omp1018.mail.ird.yahoo.com with NNFMP; 06 Jul 2012 10:27:54 -0000 X-DKIM-Result: Domain=yahoo.co.uk Result=Good and Known Domain X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 141326.54669.bm@omp1018.mail.ird.yahoo.com Received: (qmail 14288 invoked by uid 60001); 6 Jul 2012 10:27:54 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s1024; t=1341570474; bh=/drB5xL5S+Fdo/lIwK3CHtTyuHU/XwBS0lfP4gDTQ8c=; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=SBLiocyXrVBeeQVmxbACwklYZ+fk2xLsEghWvhFOs09jNGYtsGIblTE70z5lwVXMRsp3MqYGuP2GDLrrZBVB92dFs6dR1KHmDcQ2vuN2qUsFHfuUDRAcG1I010ikzheN+UeTZQg+1q8aKZeTMzJp8QuvmP/XW0UB75Sqg6tDXiI= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.co.uk; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=kvQii8zSqkufwTttTLAu7TZSdgPIf+gkRHl6mfdp0F531zHMG86dDqkLx78Ehxiqd0hwLDw7Uv0n+FqtHpBCpv0Q8YpGzC5jO1wR+QSkzZPgr0QW8H6xbDPkLnbdLEAmUWVchgvf4HHJkcjlTRRDueYOwoIys3wzy0+aSe9/oC4=; X-YMail-OSG: EHTnpGMVM1k9qx2YC5Gj8iLh3zQUMlkXgwbNnhguEYDfvyy 3lMg0K3RIxFc2MKCa8LCnief75uLZfIW8.hpWK2gyxynYxKKbhLlsNF866NO PtWz_8ej1oOqVa8PLB75H3.5CRpXk1LGGdfJz4r944iL8eOAF11eNm0qSP8u 4U2XUsm4i7kd2WOMv24bZirA3cVQigwujsT_NKI7nfVgF7ji4_GPuj3kbYI4 Lh7KQBxrVeEpmqEV9Kw9Mk_bglRTAEtiMZgbU.hWRjta7P7n66if8ZRm7krn Bod2cVUiuzCzgaUy20lho_ZOAAr_RGFYL4aDxspZXc7xxvMGbYK06Mq3yl8Q Y77C_ivZRAnOf31eiQ8IMf4sZQv6mxZecKVS1Vd_5d5si_cwT.pDRZmFyzBu MiW8qaTMX0AqTNBkT1MHxovnQZmaPjb_2VDvBJrClMfHwf_6DPXd32jgTIkX xNKdyjHOlazkRnolqiiJCSh_9qYDkGQhWVP.tFnyIhfsRneHTTa8rDmopVEV sFWEQ4KG0QL8WW6TnrIdoJ9u1L9ftjC3gM606F_OOmff2p_Jntu3Lajxcfns ELMOOvTjGG6N.VvNVrIEkek9qtDF_mqI. Received: from [86.161.210.127] by web171601.mail.ir2.yahoo.com via HTTP; Fri, 06 Jul 2012 11:27:53 BST X-Mailer: YahooMailWebService/0.8.120.356233 References: <4FF61402.6000703@iup.uni-heidelberg.de> Message-ID: <1341570473.13429.YahooMailNeo@web171601.mail.ir2.yahoo.com> Date: Fri, 6 Jul 2012 11:27:53 +0100 (BST) From: M0FMT To: "rsgb_lf_group@blacksheep.org" In-Reply-To: MIME-Version: 1.0 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 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. [...] 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 [77.238.189.65 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (m0fmt[at]yahoo.co.uk) 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 FSL_FREEMAIL_2 FSL_FREEMAIL_2 0.0 FSL_FREEMAIL_1 FSL_FREEMAIL_1 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: fbdd513523001863775249cfaf215eac Subject: Re: LF: RE: Analog oscillators [Vackar] Content-Type: multipart/alternative; boundary="-1613889061-896860266-1341570473=:13429" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE, MAILTO_TO_SPAM_ADDR,TO_ADDRESS_EQ_REAL 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: 0:2:380129504:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m025.1 ; domain : yahoo.co.uk DKIM : fail x-aol-sid: 3039ac1d41154ff6bdf83338 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ---1613889061-896860266-1341570473=:13429 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hi Stefan and group=0A=A0=0ALook carefully at the circuit for the VACKAR VF= O 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 o= f "Unobtainium" its like any other free running osc.=0A=A0=0AThey are not m= ade now but someone is selling old bits for about 35 dollars US at http://w= ww.bmius.com/p-9560-oxley-xxx-tempatrimmer.aspx=A0 =0A=A0=0AThat sort of pr= ice will get you a modern DDS with all the facilities but IMHE they are sus= ceptible 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.=0A=A0=0ABeating two x= tals works for me but I have never checked the stability seriously. It work= s OK for 500kc/s because these are standard xtals 60P ea (probably of dubio= us 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.=0AThe Si57x is anoth= er 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.=0A=0A73 es GL= Pete M0FMT IO91UX=0A=0A=0A>________________________________=0A> From: Dave= G3WCB. =0A>To: rsgb_lf_group@blacksheep.org = =0A>Sent: Friday, 6 July 2012, 8:43=0A>Subject: LF: RE: Analog oscillators = [Vackar]=0A> =0A>Hi, Stefan, LF,=0A>=0A>I suggest you consider the Vackar = oscillator. There is a very good=0A>FET/transistor design by G3PDM which yo= u can reach by following the link=0A>below.=0A>=0A>It's also important to c= onsider the mechanical design of the oscillator and=0A>its enclosure. I thi= nk you'll be disappointed with the results of your=0A>construction - the ti= nplate box will be quite "flimsy", and the arrangement=0A>with the tuning c= apacitor in the lid means that you will have quite long=0A>unsupported wire= s connecting the frequency determining components.=0A>=0A>I suggest that yo= u start with a more rigid metal box, say an aluminium=0A>die-cast box, and = mount all the rf components, including the coil, close=0A>together and as r= igidly as possible. In the past I have used ceramic=0A>stand-off pillars, b= ut strips of fibreglass PC board material soldered to M3=0A>screws works ju= st as well. For the coil, use a styrene or ceramic former=0A>with a dust-ir= on (not ferrite) tuning slug. Avoid toroids for the oscillator=0A>coil, if = possible.=0A>=0A>The G3PDM article has some useful information on mechanica= l constuction.=0A>There was a load of work done by hams and professionals o= n transistor=0A>oscillators in the 1970s and 1980s, but it's been largely f= orgotten with the=0A>introduction of PLLs and DDSs. It just needs to be re-= discovered!=0A>=0A>Good luck!=0A>=0A>73, Dave G3WCB IO91RM=0A>=0A>http://ww= w.qsl.net/va3diw/vackar.html=0A>=0A>=0A>=0A>>=0A>> The NE602 works very wel= l as oscillator and delivers a clean and low=0A>> noise signal.=0A>> One of= the main problem in building VFO's is the mechanical design.=0A>> It can b= e done, but it is not trivial when you use a tuning capacitor=0A>> and gear= box.=0A>> Mechanical rigidity and freedom from micropfonics requires a soli= d=0A>> enclosure which with the gearbox need to be mounted on the frontpane= l,=0A>> rather than on the chassis.=0A>>=0A>> As the frequency range is sma= ll, it will be mechanically much easier=0A>> to use varactor tuning in conj= unction with a ten turn potmeter. I have=0A>> been there and done it all.= =0A>> I have build a 40 m receiver with varactor tuning and it is rock stab= le.=0A>>=0A>> Building VFO's is fun!=0A>>=0A>> 73,=0A>> Roelof, pa0rdt=0A>>= =0A>=0A>=0A> ---1613889061-896860266-1341570473=:13429 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hi Stefan and group=
 
Look carefully at the= circuit for the VACKAR VFO which has been hawked around in the RSGB Handbo= ok for years. Note in the bottom LH corner of the schematic Oxley "TEMPATRI= MMER" without this piece of "Unobtainium" its like any other free running o= sc.
 
They are not made = now but someone is selling old bits for about 35 dollars US at http://www.bmius.co= m/p-9560-oxley-xxx-tempatrimmer.aspx 
 
That sort of price will get you a modern DDS with= all the facilities but IMHE th= ey 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 seri= ously. It works OK for 500kc/s because these are standard xtals 60P ea (pro= bably 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 r= ange of closely set spot QRGs. Look in the archive of the Softrock Yahoo gr= oup for the design and software details of = the "Xtall" LO.
73 es GL Pete M0FMT IO91UX
From: Dave G3WCB. <ganymede444@btopenworld.com&= gt;
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 th= e link
below.

It's also important to consider the mechanical desi= gn of the oscillator and
its enclosure. I think you'll be disappointed w= ith the results of your
construction - the tinplate box will be quite "f= limsy", and the arrangement
with the tuning capacitor in the lid means t= hat you will have quite long
unsupported wires connecting the frequency = determining components.

I suggest that you start with a more rigid m= etal 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, u= se a styrene or ceramic former
with a dust-iron (not ferrite) tuning slu= g. Avoid toroids for the oscillator
coil, if possible.

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

G= ood luck!

73, Dave G3WCB IO91RM

http://www.qsl.net/va3diw/vackar.htm= l



>
> The NE602 works very well as oscillator a= nd delivers a clean and low
> noise signal.
> One of the main p= roblem 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.<= br>> Mechanical rigidity and freedom from micropfonics requires a solid<= br>> enclosure which with the gearbox need to be mounted on the frontpan= el,
> rather than on the chassis.
>
> As the frequency range is small, it will be mechanically much easier
> to use varacto= r 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!
>
&= gt; 73,
> Roelof, pa0rdt
>


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