Message-ID: <4D25A83F.7000706@iup.uni-heidelberg.de>
Date: Thu, 06 Jan 2011 12:32:15 +0100
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: 500kHz Classe-E
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Hi Andy,

I've built class E PAs for 2.2km, 160m, 80m, 40m, 30m, 17m and 10m, so i 
have some experience. See some comments below...

Am 06.01.2011 10:29, schrieb Andy Talbot:
> As I have all the bits available as surplus junk on the shelves, 
> thought I would put together a QRO class-E  PA based around Alan's 
> spreadsheet, (with mod for matching built in).
> But before comitting to any particular power level / supply voltgage 
> combination thought I'd ask what others have reliably achieved with a 
> similar setup.
> Starting parameters :
>    Supply voltage anything from 28 - 55V adjustable.  25 A max
>    PA device  - IRFP452 (have a small handful, so can allow a few to 
> go pop)  Rated 500V,   0.4 Rdson, 14A,  190 Watts
>    Drive, accurate 50% square wave from ICL7667
>    Resonant Inductor -  air wound with 2mm Litz wire.
> I reckon that at 55V 500 Watts might be a value to aim for with a 
> single device, with the option to back off by lowering Vsupply.
> But before committing to winding inductors and making parallel 
> combination of high voltage caps, does anyone have any practical 
> experience?   Am I aiming for too high a power perhaps.
No, 500W by one of these FETs at 500 kHz should be possible, although 
the efficiency will probably be 85 to 90%. But if you have a 55V/25A 
supply, why don't you develop a 1 kW PA? If it is designed to give 1 kW 
at 50V, you'll get a good 50W at a car battery so it is even usable in 
/p or /m :-)
Due to the relative high gate capacity the 7667 might be not the optimal 
choice although it will work. If you have a couple of these FETs i 
personally would use 4 of them in parallel and use a IXDD414 as the 
driver. This will allow you to get an efficiency of say 96% (if the 
coils are fine and suitable impulse Cs are used). A 500V device and 55V 
supply voltage is a high buffer but that's no disadvantage :-)

I've built a 600W class E PA running at 36VDC using 4xIRFP260N and a 
IXDD414. Its efficiency is 95% and the size of the whole PA (exclusive 
power supply) is 10cm*16cm*8cm...

Good luck and fun,

73, Stefan/DK7FC


> Andy
> www.g4jnt.com <http://www.g4jnt.com/>

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Hi Andy,<br>
<br>
I've built class E PAs for 2.2km, 160m, 80m, 40m, 30m, 17m and 10m, so
i have some experience. See some comments below...<br>
<br>
Am 06.01.2011 10:29, schrieb Andy Talbot:
<blockquote   cite="mid:AANLkTim3_ub5p7DZfo=ZxSPy6BsX2TjBKsGbu14KedSZ@mail.gmail.com"   type="cite">
  <div>As I have all the bits available as surplus junk on the shelves,
thought I would put together a QRO class-E&nbsp; PA based around Alan's
spreadsheet, (with mod for&nbsp;matching built in).</div>
  <div>But before comitting to any particular power level / supply
voltgage combination thought I'd ask what others have reliably achieved
with a similar setup.</div>
  <div>&nbsp;</div>
  <div>Starting&nbsp;parameters :</div>
  <div>&nbsp;&nbsp; Supply voltage anything from 28 - 55V adjustable.&nbsp; 25 A max</div>
  <div>&nbsp;&nbsp; PA device&nbsp; - IRFP452 (have a small handful, so can allow a
few to go pop)&nbsp; Rated 500V,&nbsp;&nbsp; 0.4 Rdson, 14A, &nbsp;190 Watts</div>
  <div>&nbsp;&nbsp; Drive, accurate 50% square wave from ICL7667</div>
  <div>&nbsp;&nbsp; Resonant Inductor - &nbsp;air wound&nbsp;with 2mm Litz wire.</div>
  <div>&nbsp;</div>
  <div>I reckon that at 55V 500 Watts might be a value to aim for with
a single device, with the option to back off by lowering Vsupply.</div>
  <div>But before committing&nbsp;to winding inductors and making parallel
combination of high voltage caps, does anyone have any practical
experience?&nbsp;&nbsp; Am&nbsp;I aiming for too high a power perhaps.</div>
</blockquote>
No, 500W by one of these FETs at 500 kHz should be possible, although
the efficiency will probably be 85 to 90%. But if you have a 55V/25A
supply, why don't you develop a 1 kW PA? If it is designed to give 1 kW
at 50V, you'll get a good 50W at a car battery so it is even usable in
/p or /m :-)<br>
Due to the relative high gate capacity the 7667 might be not the
optimal choice although it will work. If you have a couple of these
FETs i personally would use 4 of them in parallel and use a IXDD414 as
the driver. This will allow you to get an efficiency of say 96% (if the
coils are fine and suitable impulse Cs are used). A 500V device and 55V
supply voltage is a high buffer but that's no disadvantage :-)<br>
<br>
I've built a 600W class E PA running at 36VDC using 4xIRFP260N and a
IXDD414. Its efficiency is 95% and the size of the whole PA (exclusive
power supply) is 10cm*16cm*8cm...<br>
<br>
Good luck and fun,<br>
<br>
73, Stefan/DK7FC<br>
<br>
<br>
<blockquote   cite="mid:AANLkTim3_ub5p7DZfo=ZxSPy6BsX2TjBKsGbu14KedSZ@mail.gmail.com"   type="cite">
  <div>&nbsp;</div>
  <div>Andy</div>
  <div><a moz-do-not-send="true" href="http://www.g4jnt.com/">www.g4jnt.com</a></div>
  <div>&nbsp;</div>
</blockquote>
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