Message-ID: <4C8686CF.9060100@iup.uni-heidelberg.de>
Date: Tue, 07 Sep 2010 20:39:11 +0200
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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To: rsgb_lf_group@blacksheep.org
References: <AANLkTi=1Ek-zT3aME0u3k28kXM9mm2mxhUYpDoWSj3xh@mail.gmail.com> <AANLkTin+tDCQkGdFjv92fEx_OtWAyN_N_FS1SpOz0H27@mail.gmail.com>
In-Reply-To: <AANLkTin+tDCQkGdFjv92fEx_OtWAyN_N_FS1SpOz0H27@mail.gmail.com>
Subject: Re: LF: 137.5kHz WSPR Tuesday evening - reports appreciated
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Hello Roger,

Maybe you can send us a circuit with its values. I have built class E PA 
for 2200/160/80/40/30/17/10m and have some experience. If you are using 
a IRF510 and stay in the QRP range (< 10 W) at 137 in a class E stage 
you wouldn't even need a heat sink at all if well dimensioned!

See the infos at http://www.classeradio.com/  This is most useful if you 
are starting with that design. On 137 kHz problems are much smaller than 
on HF :-)

Best 73, Stefan/DK7FC

Am 07.09.2010 20:17, schrieb Roger Lapthorn:
> Just hit a bit of a snag and blew up my (last) IRF510 PA because of 
> totally inadequate heatsink. So, I'm on 137.5kHz WSPR but only with 
> about 1W from the simpler PA at present, so ERP low uWs.  I need to 
> get some heatsink and more FETs!
>
> Any reports (now less likely) still appreciated.
>
> [Mal - it started out as a Class E design attempt but hadn't been 
> optimised, so I guess this counts as class D. ]
>
> 73s
> Roger G3XBM
>
>
>
> On 7 September 2010 17:34, Roger Lapthorn <rogerlapthorn@gmail.com 
> <mailto:rogerlapthorn@gmail.com>> wrote:
>
>     My 137.5kHz WSPR TX transverter is now working fine, so I'll be
>     _*on-air with WSPR tonight (Sept 7th) from 5.30pm - 11pm UK time*_.
>
>     After my success on QRSS3 with G3XIZ I'm hopeful he'll now decode
>     my WSPR signal tonight, assuming Chris can take a listen. If
>     anyone else within, say, 100km of Burwell, Cambs JO02dg cares to
>     take a look for the WSPR beacon (running around 35% TX time) I'd
>     be /most/ grateful.
>
>     Not sure if anyone else has had this problem, but I /was/ using
>     the small 16mm 3C90 cores (cream colour) as the PA bifilar output
>     transformer and I had all sorts of issues with the darn thing
>     overheating and even one cracking. I replaced this with a choke
>     wound on a T106-2 core and made the output network work in class
>     D/E and now everything is working very predictably. The larger
>     diameter 3C90 cores seem fine in the step-down transformer
>     matching the "in the air" loop.
>
>     The WSPR beacon is now going ON.....
>
>     73s
>     Roger G3XBM
>
>
>     -- 
>     http://g3xbm-qrp.blogspot.com/
>     http://www.g3xbm.co.uk
>     http://www.youtube.com/user/g3xbm
>     G3XBM   GQRP 1678    ISWL G11088
>
>
>
>
> -- 
> http://g3xbm-qrp.blogspot.com/
> http://www.g3xbm.co.uk
> http://www.youtube.com/user/g3xbm
> G3XBM   GQRP 1678    ISWL G11088

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Hello Roger,<br>
<br>
Maybe you can send us a circuit with its values. I have built class E
PA for 2200/160/80/40/30/17/10m and have some experience. If you are
using a IRF510 and stay in the QRP range (&lt; 10 W) at 137 in a class
E stage you wouldn't even need a heat sink at all if well dimensioned!<br>
<br>
See the infos at <a class="moz-txt-link-freetext" href="http://www.classeradio.com/">http://www.classeradio.com/</a>&nbsp; This is most useful if
you are starting with that design. On 137 kHz problems are much smaller
than on HF :-)<br>
<br>
Best 73, Stefan/DK7FC<br>
<br>
Am 07.09.2010 20:17, schrieb Roger Lapthorn:
<blockquote   cite="mid:AANLkTin+tDCQkGdFjv92fEx_OtWAyN_N_FS1SpOz0H27@mail.gmail.com"   type="cite">Just hit a bit of a snag and blew up my (last) IRF510 PA
because of totally inadequate heatsink. So, I'm on 137.5kHz WSPR but
only with about 1W from the simpler PA at present, so ERP low uWs.&nbsp; I
need to get some heatsink and more FETs!<br>
  <br>
Any reports (now less likely) still appreciated.<br>
  <br>
[Mal - it started out as a Class E design attempt but hadn't been
optimised, so I guess this counts as class D. ]<br>
  <br>
73s<br>
Roger G3XBM<br>
  <br>
  <br>
  <br>
  <div class="gmail_quote">On 7 September 2010 17:34, Roger Lapthorn <span   dir="ltr">&lt;<a moz-do-not-send="true"   href="mailto:rogerlapthorn@gmail.com">rogerlapthorn@gmail.com</a>&gt;</span>
wrote:<br>
  <blockquote class="gmail_quote"   style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">My
137.5kHz WSPR TX transverter is now working fine, so I'll be <u><b>on-air
with WSPR tonight (Sept 7th) from 5.30pm - 11pm UK time</b></u>. <br>
    <br>
After my success on QRSS3 with G3XIZ I'm hopeful he'll now decode my
WSPR signal tonight, assuming Chris can take a listen. If anyone else
within, say, 100km of Burwell, Cambs JO02dg cares to take a look for
the WSPR beacon (running around 35% TX time) I'd be <i>most</i>
grateful. <br>
    <br>
Not sure if anyone else has had this problem, but I <i>was</i> using
the small 16mm 3C90 cores (cream colour) as the PA bifilar output
transformer and I had all sorts of issues with the darn thing
overheating and even one cracking. I replaced this with a choke wound
on a T106-2 core and made the output network work in class D/E and now
everything is working very predictably. The larger diameter 3C90 cores
seem fine in the step-down transformer matching the "in the air" loop.<br>
    <br>
The WSPR beacon is now going ON.....<br>
    <br>
73s<br>
Roger G3XBM<br>
    <font color="#888888"><br clear="all">
    <br>
-- <br>
    <a moz-do-not-send="true" href="http://g3xbm-qrp.blogspot.com/"   target="_blank">http://g3xbm-qrp.blogspot.com/</a><br>
    <a moz-do-not-send="true" href="http://www.g3xbm.co.uk"   target="_blank">http://www.g3xbm.co.uk</a><br>
    <a moz-do-not-send="true" href="http://www.youtube.com/user/g3xbm"   target="_blank">http://www.youtube.com/user/g3xbm</a><br>
G3XBM&nbsp;&nbsp; GQRP 1678&nbsp;&nbsp;&nbsp; ISWL G11088<br>
    </font></blockquote>
  </div>
  <br>
  <br clear="all">
  <br>
-- <br>
  <a moz-do-not-send="true" href="http://g3xbm-qrp.blogspot.com/"   target="_blank">http://g3xbm-qrp.blogspot.com/</a><br>
  <a moz-do-not-send="true" href="http://www.g3xbm.co.uk"   target="_blank">http://www.g3xbm.co.uk</a><br>
  <a moz-do-not-send="true" href="http://www.youtube.com/user/g3xbm"   target="_blank">http://www.youtube.com/user/g3xbm</a><br>
G3XBM&nbsp;&nbsp; GQRP 1678&nbsp;&nbsp;&nbsp; ISWL G11088<br>
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