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Date: Tue, 7 Sep 2010 19:17:19 +0100
Message-ID: <AANLkTin+tDCQkGdFjv92fEx_OtWAyN_N_FS1SpOz0H27@mail.gmail.com>
From: Roger Lapthorn <rogerlapthorn@gmail.com>
To: rsgb_lf_group@blacksheep.org, Chris Osborn <g3xiz@yahoo.co.uk>, 
	G6ALB <andrew@tetrode.co.uk>, James Cowburn <james.cowburn@virgin.net>, 
	Chris Dillon <c.r.dillon@dsl.pipex.com>, James Moritz <james.moritz@btopenworld.com>, 
	mike.dennison@ntlworld.com
DomainKey-Status: good (testing) 
Subject: Re: LF: 137.5kHz WSPR Tuesday evening - reports appreciated
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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> 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

--001636c5b4565d7a15048faf6823
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Content-Transfer-Encoding: quoted-printable

Just hit a bit of a snag and blew up my (last) IRF510 PA because of totall=
y inadequate heatsink. So, I&#39;m on 137.5kHz WSPR but only with about 1W=
 from the simpler PA at present, so ERP low uWs.=A0 I need to get some hea=
tsink and more FETs!<br>
<br>Any reports (now less likely) still appreciated.<br><br>[Mal - it star=
ted out as a Class E design attempt but hadn&#39;t been optimised, so I gu=
ess this counts as class D. ]<br><br>73s<br>Roger G3XBM<br><br><br><br><di=
v class=3D"gmail_quote">
On 7 September 2010 17:34, Roger Lapthorn <span dir=3D"ltr">&lt;<a href=3D=
"mailto:rogerlapthorn@gmail.com">rogerlapthorn@gmail.com</a>&gt;</span> wr=
ote:<br><blockquote class=3D"gmail_quote" style=3D"margin: 0pt 0pt 0pt 0.8=
ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
My 137.5kHz WSPR TX transverter is now working fine, so I&#39;ll be <u><b>=
on-air with WSPR tonight (Sept 7th) from 5.30pm - 11pm UK time</b></u>. <b=
r><br>After my success on QRSS3 with G3XIZ I&#39;m hopeful he&#39;ll now=
 decode my WSPR signal tonight, assuming Chris can take a listen. If anyon=
e else within, say, 100km of Burwell, Cambs JO02dg cares to take a look fo=
r the WSPR beacon (running around 35% TX time) I&#39;d be <i>most</i> grat=
eful. <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 transfo=
rmer and I had all sorts of issues with the darn thing overheating and eve=
n one cracking. I replaced this with a choke wound on a T106-2 core and ma=
de 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 tr=
ansformer matching the &quot;in the air&quot; loop.<br>

<br>The WSPR beacon is now going ON.....<br><br>73s<br>Roger G3XBM<br><fon=
t color=3D"#888888"><br clear=3D"all"><br>-- <br><a href=3D"http://g3xbm-q=
rp.blogspot.com/" target=3D"_blank">http://g3xbm-qrp.blogspot.com/</a><br>=
<a href=3D"http://www.g3xbm.co.uk" target=3D"_blank">http://www.g3xbm.co.u=
k</a><br>

<a href=3D"http://www.youtube.com/user/g3xbm" target=3D"_blank">http://www=
.youtube.com/user/g3xbm</a><br>G3XBM=A0=A0 GQRP 1678=A0=A0=A0 ISWL G11088<=
br>
</font></blockquote></div><br><br clear=3D"all"><br>-- <br><a href=3D"http=
://g3xbm-qrp.blogspot.com/" target=3D"_blank">http://g3xbm-qrp.blogspot.co=
m/</a><br><a href=3D"http://www.g3xbm.co.uk" target=3D"_blank">http://www.=
g3xbm.co.uk</a><br>
<a href=3D"http://www.youtube.com/user/g3xbm" target=3D"_blank">http://www=
.youtube.com/user/g3xbm</a><br>G3XBM=A0=A0 GQRP 1678=A0=A0=A0 ISWL G11088<=
br>

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