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Message-ID: <613358.97685.qm@web28104.mail.ukl.yahoo.com>
Date: Wed, 7 Apr 2010 15:41:44 -0700 (PDT)
From: M0FMT <m0fmt@yahoo.co.uk>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <2C18FDA91B0849C5958253F77FE7EF50@JimPC>
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Subject: Re: LF: WSPR without an SSB TRX ?
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Hi Jim
=A0
If you mix the 1500hz tone up to 500 kc/s conventionally don't you get +/-=
 1500hz tone as the product. i.e. upper and lower sideband? Even if a doub=
le sideband signal was acceptable on 500 it would only fit in the band exa=
ctly and the sidebands on the side bands would be out of band or have I mi=
ssed something?
=A0
Thus the reason I suggested a Tayloe (for the want of a better description=
) detector in reverse which resolves the unwanted sideband issue. I dont=
 think a straight forward product mixer will do.
=A0
A simple phase modulator using two 8meg xtals by G3ZJO is shown on=A0a web=
 page the URL in my last mail.=A0

73 es GL petefmt

--- On Wed, 7/4/10, James Moritz <james.moritz@btopenworld.com> wrote:


From: James Moritz <james.moritz@btopenworld.com>
Subject: Re: LF: WSPR without an SSB TRX ?
To: rsgb_lf_group@blacksheep.org
Date: Wednesday, 7 April, 2010, 23:25


Dear Chris, LF Group,

----- Original Message ----- From: "Chris Osborn" <g3xiz@yahoo.co.uk>

...>My initial thoughts were that the PC is giving out a 1500 Hz tone + /=
 - 5 Hz.
This is used to generate USB signals from an SSB TX (?)
I was hoping to mix these tones with a stable frequency of 1400 Hz (say)=
 ending up
with 100 Hz + / - 5 Hz - thence to an F-V converter - gain / level adjuste=
d and thence
to the TX VCO input....>

That is probably feasible, if quite tricky - but much easier just to mix=
 the 1500Hz tone up directly to 500kHz to generate the VFO drive for your=
 existing TX PA; that way only a simple fixed oscillator is required (one=
 using a ceramic resonator would be adequately stable and "pullable" over=
 a sufficient range). You then avoid all the business of having to calibra=
te the f/V gain, VCO frequency shift and so on. Plus, you can tune the fre=
quency by changing the centre frequency setting in the software, and use=
 it to transmit all sorts of other soundcard mFSK modes, RTTY etc.,=A0 too=
.

Cheers, Jim Moritz
73 de M0BMU=20




     =20

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<table cellspacing=3D"0" cellpadding=3D"0" border=3D"0" ><tr><td valign=3D=
"top" style=3D"font: inherit;"><DIV>Hi Jim</DIV>
<DIV>&nbsp;</DIV>
<DIV>If you mix the 1500hz tone up to 500 kc/s conventionally don't you ge=
t +/- 1500hz tone as the product. i.e. upper and lower sideband? Even if=
 a double sideband signal was acceptable on 500 it would only fit in the=
 band exactly and the sidebands on the side bands would be out of band or=
 have I missed something?</DIV>
<DIV>&nbsp;</DIV>
<DIV>Thus the reason I suggested a Tayloe (for the want of a better descri=
ption) detector in reverse which resolves the unwanted sideband issue. I=
 dont think a straight forward product mixer will do.</DIV>
<DIV>&nbsp;</DIV>
<DIV>A simple phase modulator using two 8meg xtals by G3ZJO is shown on&nb=
sp;a web page the URL in my last mail.&nbsp;<BR><BR>73 es GL petefmt<BR><B=
R>--- On <B>Wed, 7/4/10, James Moritz <I>&lt;james.moritz@btopenworld.com&=
gt;</I></B> wrote:<BR></DIV>
<BLOCKQUOTE style=3D"BORDER-LEFT: rgb(16,16,255) 2px solid; PADDING-LEFT:=
 5px; MARGIN-LEFT: 5px"><BR>From: James Moritz &lt;james.moritz@btopenworl=
d.com&gt;<BR>Subject: Re: LF: WSPR without an SSB TRX ?<BR>To: rsgb_lf_gro=
up@blacksheep.org<BR>Date: Wednesday, 7 April, 2010, 23:25<BR><BR>
<DIV class=3DplainMail>Dear Chris, LF Group,<BR><BR>----- Original Message=
 ----- From: "Chris Osborn" &lt;<A href=3D"http://uk.mc281.mail.yahoo.com/=
mc/compose?to=3Dg3xiz@yahoo.co.uk" ymailto=3D"mailto:g3xiz@yahoo.co.uk">g3=
xiz@yahoo.co.uk</A>&gt;<BR><BR>...&gt;My initial thoughts were that the PC=
 is giving out a 1500 Hz tone + / - 5 Hz.<BR>This is used to generate USB=
 signals from an SSB TX (?)<BR>I was hoping to mix these tones with a stab=
le frequency of 1400 Hz (say) ending up<BR>with 100 Hz + / - 5 Hz - thence=
 to an F-V converter - gain / level adjusted and thence<BR>to the TX VCO=
 input....&gt;<BR><BR>That is probably feasible, if quite tricky - but muc=
h easier just to mix the 1500Hz tone up directly to 500kHz to generate the=
 VFO drive for your existing TX PA; that way only a simple fixed oscillato=
r is required (one using a ceramic resonator would be adequately stable an=
d "pullable" over a sufficient range). You then avoid all the business of=
 having to
 calibrate the f/V gain, VCO frequency shift and so on. Plus, you can tune=
 the frequency by changing the centre frequency setting in the software,=
 and use it to transmit all sorts of other soundcard mFSK modes, RTTY etc.=
,&nbsp; too.<BR><BR>Cheers, Jim Moritz<BR>73 de M0BMU <BR><BR></DIV></BLOC=
KQUOTE></td></tr></table><br>



     =20

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