Message-ID: <50BBCD5C.9020808@iup.uni-heidelberg.de>
Date: Sun, 02 Dec 2012 22:51:24 +0100
From: =?ISO-8859-2?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Problem with generator to VLF transmitter
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Hi Marcin,

Am 02.12.2012 21:42, schrieb Marcin:
>
> What we still need is a generator to feed the transmitter. Required 
> parameters are the following:
>
>     * 8,970kHz frequency
>     * regulating range +-0.05Hz
>     * adjusting duty cycle of 5 to 45%, at 5% for two signals at the
>       same time
>     * two signals shifted by 180 degrees
>
> A friend of mine has promised to build it but it's been over a year 
> now and nothing has happened.
> Is there a software which would use a soundcard with the 
> aforementioned parameters?

You can generate the 8.97 kHz signal in SpecLab and use a reference 
signal to compensate the soundcard drift. See the circuit of my first PA 
to see how the drive stage is made: 
http://www.iup.uni-heidelberg.de/schaefer_vlf/12V_300W_VLF_PA.pdf
This is easily done and you have most of the circuit already working.

For what do you need to vary the duty cicle from 5...45% ? Is this to 
adjust the TX power? Or do you want a quasi-linear mode PA? For normal 
power adjustments i suggest to use simple taps on the secondary winding 
of the PA output transformer.

An alternative may be DF6NM's outphasing program which he will describe 
for you :-)

73 and please keep us informed about the progress. There is some growing 
interest in the 33km band again, also here in DL :-)

73, GL, Stefan/DK7FC

PS: That was a short answer, sri.

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Hi Marcin, <br>
<br>
Am 02.12.2012 21:42, schrieb Marcin:
<blockquote cite=3D"mid:003f01cdd0cd$7ba8de30$6600a8c0@dupaod6d2sep9z"
 type=3D"cite">
  <meta http-equiv=3D"Content-Type"
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  <div><br>
  <div>What we still need is a generator to feed the transmitter.
Required parameters are the following:</div>
  <ul>
    <li>8,970kHz frequency </li>
    <li>regulating range=A0+-0.05Hz </li>
    <li><font face=3D"Arial" size=3D"2">adjusting duty cycle of 5 to 45%,
at 5% for two signals at the same time</font> </li>
    <li><font face=3D"Arial" size=3D"2">two signals shifted by 180 degree=
s</font></li>
  </ul>
  <div>A friend of mine has promised to build it but it&#8217;s been over=
 a
year now and nothing has happened.</div>
  <div>Is there a software which would use a soundcard with the
aforementioned parameters?</div>
  </div>
</blockquote>
<br>
You can generate the 8.97 kHz signal in SpecLab and use a reference
signal to compensate the soundcard drift. See the circuit of my first
PA to see how the drive stage is made:
<a class=3D"moz-txt-link-freetext" href=3D"http://www.iup.uni-heidelberg.=
de/schaefer_vlf/12V_300W_VLF_PA.pdf">http://www.iup.uni-heidelberg.de/sch=
aefer_vlf/12V_300W_VLF_PA.pdf</a><br>
This is easily done and you have most of the circuit already working. <br=
>
<br>
For what do you need to vary the duty cicle from 5...45% ? Is this to
adjust the TX power? Or do you want a quasi-linear mode PA? For normal
power adjustments i suggest to use simple taps on the secondary winding
of the PA output transformer. <br>
<br>
An alternative may be DF6NM's outphasing program which he will describe
for you :-)<br>
<br>
73 and please keep us informed about the progress. There is some
growing interest in the 33km band again, also here in DL :-)<br>
<br>
73, GL, Stefan/DK7FC<br>
<br>
PS: That was a short answer, sri.<br>
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