Message-ID: <4D225D7D.5090105@iup.uni-heidelberg.de>
Date: Tue, 04 Jan 2011 00:36:29 +0100
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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Subject: Re: VLF: DK7FC's "big" VLF PA - Outphasing
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Hi Markus,

Interesting! This could be easily done of course. If it is possible to=20
modify your chirped hell software to drive such a PA in SpecLab, i would=
=20
build a separate LF/VLF PA. It's time to transmit a smiley on the kite=20
antenna (visible in a DFCW-600 window), at full power! :-) The minimum=20
symbol rate of chirped hell within SL has to be reduced for that purpose.

My birthday is May, 26th, so you have some time for that! When is your=20
birthday? I would congratulate in chirped hell on VLF ;-)

73, Stefan/DK7FC



Am 04.01.2011 00:00, schrieb Markus Vester:
> Dear Stefan,
> thanks very much for sharing this very useful design!
> Just in case you would like to extend this to linear modulation: The=20
> H-bridge topology naturally lends itself to the Outphasing technique=20
> (aka "Chireix" modulation", "Ampliphase", "LINC"), which was=20
> invented in the 1930ies to increase AM transmitter efficiency. The=20
> idea is to drive the two half-bridges separately with a variable phase=
=20
> difference: 180=B0 gives full power, 90=B0 gives -3 dB, and 0=B0 gives=
 no=20
> differential output across the load.
> Instead of generating the two carriers by special envelope-driven=20
> phaseshifter hardware, you could also take a software approach through=
=20
> the two outputs of a stereo soundcard. It may then be best to feed the=
=20
> PA drivers directly, avoiding the dividers which can introduce an=20
> unwanted 180=B0 ambiguity.
> If you feel like trying this concept, I could be persuaded to adapt=20
> the Chirped Hell software for this purpose. What day is your birthday?=
=20
> ;-))
> Best regards,
> Markus (DF6NM)
> PS: In case you decide to use small audio transformers at the input,=20
> make sure their insulation can safely withstand the line voltage!

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta content=3D"text/html; charset=3DISO-8859-15"   http-equiv=3D"Conte=
nt-Type">
</head>
<body bgcolor=3D"#ffffff" text=3D"#000000">
Hi Markus,<br>
<br>
Interesting! This could be easily done of course. If it is possible to
modify your chirped hell software to drive such a PA in SpecLab, i
would build a separate LF/VLF PA. It's time to transmit a smiley on the
kite antenna (visible in a DFCW-600 window), at full power! :-) The
minimum symbol rate of chirped hell within SL has to be reduced for
that purpose.<br>
<br>
My birthday is May, 26th, so you have some time for that! When is your
birthday? I would congratulate in chirped hell on VLF ;-)<br>
<br>
73, Stefan/DK7FC<br>
<br>
<br>
<br>
Am 04.01.2011 00:00, schrieb Markus Vester:
<blockquote cite=3D"mid:A4FCBFE8D0434967960A11F60799422D@White"   type=3D"=
cite">
  <meta http-equiv=3D"Content-Type"   content=3D"text/html; charset=3DISO-=
8859-15">
  <meta content=3D"MSHTML 6.00.6000.17093" name=3D"GENERATOR">
  <div><font face=3D"Arial" size=3D"2">Dear Stefan, </font></div>
  <div>=A0</div>
  <div><font face=3D"Arial" size=3D"2">thanks very much for sharing this
very useful design!</font></div>
  <div>=A0</div>
  <div><font face=3D"Arial" size=3D"2">Just in case you would like to
extend this=A0to linear modulation: </font><font face=3D"Arial" size=3D"2"=
>The
H-bridge topology naturally lends itself to the Outphasing technique
(aka "Chireix" modulation", "Ampliphase", "LINC"),=A0which was
invented=A0in the 1930ies to increase AM transmitter efficiency. The idea
is to drive the two half-bridges separately with a variable phase
difference:=A0180=B0=A0gives full power, 90=B0 gives -3 dB, and 0=B0 gives=
 no
differential output across the load.</font></div>
  <div>=A0</div>
  <div><font face=3D"Arial" size=3D"2">Instead of=A0generating the two
carriers=A0by special=A0envelope-driven phaseshifter hardware, you could
also=A0take=A0a software approach through the two outputs of a stereo
soundcard. I</font><font face=3D"Arial" size=3D"2">t may then be best to
feed the PA drivers directly, avoiding the dividers=A0which=A0can<font  =
 face=3D"Arial" size=3D"2"> introduce an unwanted=A0180=B0 ambiguity.</fon=
t></font></div>
  <div>=A0</div>
  <div><font face=3D"Arial" size=3D"2">If you feel like trying this
concept, I could be persuaded to adapt the Chirped Hell software for
this purpose. What day=A0is your birthday? ;-))</font></div>
  <div>=A0</div>
  <div><font face=3D"Arial" size=3D"2">Best regards,</font></div>
  <div><font face=3D"Arial" size=3D"2">Markus (DF6NM)</font></div>
  <div>=A0</div>
  <div>=A0</div>
  <div><font face=3D"Arial" size=3D"2">PS: In case you decide to use small
audio transformers at the input, make sure their insulation can safely
withstand the line voltage!=A0</font></div>
  <div>=A0</div>
</blockquote>
</body>
</html>

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