From: "Victor" <victor.13@ziggo.nl>
To: <rsgb_lf_group@blacksheep.org>
Date: Mon, 30 Nov 2015 20:06:57 +0100
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Subject: LF: RE: Class E PA design
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  -----Oorspronkelijk bericht-----
  Van: owner-rsgb_lf_group@blacksheep.org =
[mailto:owner-rsgb_lf_group@blacksheep.org]Namens Andy Talbot
  Verzonden: zaterdag 28 november 2015 15:54
  Aan: rsgb_lf_group@blacksheep.org; rsgb_lf_group@yahoogroups.co.uk
  Onderwerp: LF: Class E PA design


  There was a discussion a while ago about ththe PA design used here

  http://www.gw3uep.ukfsn.org/100W_QTX/100WTX/PA_pa.gif    and Alan amde =
the comment, I think that teh series capacitor at 1uF looked =
suspiciously large to be part of a tank circuit for a Class E =
transmitter.


  Well...   I've just been playing around with my spreadsheet for Class =
E stages with a built in series-L shunt-C match at the output. =
http://www.g4jnt.com/DownLoad/classe_match.xls


  For a range of transformed impedances there are two configurations =
that you can end up with.    The reactance of the series L part of the =
match can be absorbed into the tank coil, increasing its value, OR,   it =
can be absorbed into the series C DECREASING its value.  Using this =
latter solution, there will (usually)  come a point with suitable choice =
of tank Q where the reactance of the matching L exactly equals that of =
the tank capacitor, making this disappear.  =20


  That is almost certainly  what has happened in GW3UEP's design.  There =
are also a range of values where Xc tank is less than Xl match so it can =
never be absorbed, and only the one solution is possible - that of =
adding it to the tank inductor.


  To do this you have to first get a working network with some arbitrary =
Q chosen, and a valid output match for your optimum power output etc. =
Then adjust the tank Q value while watching the resulting two possible =
values shown as C2 on the spreadsheet.  As Q is altered, one will move =
toward infinity then disappear completely.


  Andy  G4JNT
  Geen virus gevonden in dit bericht.
  Gecontroleerd door AVG - www.avg.com
  Versie: 2015.0.6176 / Virusdatabase: 4460/11080 - datum van uitgifte: =
11/28/15

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=EF=BB=BF<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; charset=3Dutf-8">
<META content=3D"MSHTML 6.00.6000.20641" name=3DGENERATOR></HEAD>
<BODY>
<DIV>&nbsp;</DIV>
<BLOCKQUOTE dir=3Dltr style=3D"MARGIN-RIGHT: 0px">
  <DIV class=3DOutlookMessageHeader dir=3Dltr align=3Dleft><FONT =
face=3DTahoma=20
  size=3D2>-----Oorspronkelijk bericht-----<BR><B>Van:</B>=20
  owner-rsgb_lf_group@blacksheep.org=20
  [mailto:owner-rsgb_lf_group@blacksheep.org]<B>Namens </B>Andy=20
  Talbot<BR><B>Verzonden:</B> zaterdag 28 november 2015 =
15:54<BR><B>Aan:</B>=20
  rsgb_lf_group@blacksheep.org;=20
  rsgb_lf_group@yahoogroups.co.uk<BR><B>Onderwerp:</B> LF: Class E PA=20
  design<BR><BR></FONT></DIV>
  <DIV dir=3Dltr>There was a discussion a while ago about ththe PA =
design used=20
  here<BR>
  <DIV><A href=3D"http://www.gw3uep.ukfsn.org/100W_QTX/100WTX/PA_pa.gif" =

  =
target=3D_blank>http://www.gw3uep.ukfsn.org/100W_QTX/100WTX/PA_pa.gif</A>=
 &nbsp;=20
  &nbsp;and Alan amde the comment, I think that teh series capacitor at =
1uF=20
  looked suspiciously large to be part of a tank circuit for a Class E=20
  transmitter.<BR></DIV>
  <DIV><BR></DIV>
  <DIV>Well... &nbsp; I've just been playing around with my spreadsheet =
for=20
  Class E stages with a built in series-L shunt-C match at the =
output.&nbsp;<A=20
  href=3D"http://www.g4jnt.com/DownLoad/classe_match.xls"=20
  =
target=3D_blank>http://www.g4jnt.com/DownLoad/classe_match.xls</A></DIV>
  <DIV><BR></DIV>
  <DIV>For a range of transformed impedances there are two =
configurations that=20
  you can end up with. &nbsp; &nbsp;The reactance of the series L part =
of the=20
  match can be absorbed into the tank coil, increasing its value, OR, =
&nbsp; it=20
  can be absorbed into the series C DECREASING its value.&nbsp; Using =
this=20
  latter solution, there will (usually) &nbsp;come a point with suitable =
choice=20
  of tank Q where the reactance of the matching L exactly equals that of =
the=20
  tank capacitor, making this disappear. &nbsp;&nbsp;</DIV>
  <DIV><BR></DIV>
  <DIV>That is almost certainly &nbsp;what has happened in GW3UEP's=20
  design.&nbsp; There are also a range of values where Xc tank is less =
than Xl=20
  match so it can never be absorbed, and only the one solution is =
possible -=20
  that of adding it to the tank inductor.</DIV>
  <DIV><BR></DIV>
  <DIV>To do this you have to first get a working network with some =
arbitrary Q=20
  chosen, and a valid output match for your optimum power output etc. =
Then=20
  adjust the tank Q value while watching the resulting two possible =
values shown=20
  as C2 on the spreadsheet.&nbsp; As Q is altered, one will move toward =
infinity=20
  then disappear completely.</DIV>
  <DIV><BR></DIV>
  <DIV>Andy &nbsp;G4JNT</DIV></DIV><A></A>
  <P class=3D"" align=3Dleft color=3D"#000000" avgcert??>Geen virus =
gevonden in dit=20
  bericht.<BR>Gecontroleerd door AVG - <A=20
  href=3D"http://www.avg.com">www.avg.com</A><BR>Versie: 2015.0.6176 /=20
  Virusdatabase: 4460/11080 - datum van uitgifte:=20
11/28/15</P></BLOCKQUOTE></BODY></HTML>

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