DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws;
  s=s1024; d=yahoo.co.uk;
  h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:MIME-Version:Content-Type;
  b=uzRpW45kYnePF1FiKMf1nEzLHE07LKgaJVnVk16F0YXKMZqnQRmolZQc450lZRZtTctgM7tOvGIPqOL5TUCkeapg+eeXwYPiV6jwzFp4+a52WrYqBiOZcUTn9jCUQaCfsX+UMyUwQchkF95bmYBmNIQD1W7frafkurmaXlgQcNg=;
Message-ID: <582241.74739.qm@web28516.mail.ukl.yahoo.com>
Date: Sat, 20 Jun 2009 06:34:25 +0000 (GMT)
From: Chris Osborn <g3xiz@yahoo.co.uk>
To: LF Group <rsgb_lf_group@blacksheep.org>
MIME-Version: 1.0
DomainKey-Status: good (testing) 
Subject: LF: 500 kHz - Fans
Content-Type: multipart/alternative; boundary="0-1177915108-1245479665=:74739"
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


--0-1177915108-1245479665=:74739
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: quoted-printable

LF,
I've nearly completed my new PA for 500 kHz and have now managed to
stop destroying FET's.

Unfortunately I have an unusual problem in that the heatsink cooling fans
are going U/S.

I have used 24 volts brushless PC-type fans and after a while they
either die completely or start to go backwards slowly. . .

The fans may be slightly over-run but only by a volt or so and on key-up=20
(unregulated supply) and are situated about 50 mm (2 inches) from the heatsi=
nk.
I have rf decoupled them from the supply but=A0maybe not well enough !

Any suggestions=A0in curing this problem would be most welcome.

73 Chris G3XIZ


     =20

--0-1177915108-1245479665=:74739
Content-Type: text/html; charset=iso-8859-1
Content-Transfer-Encoding: quoted-printable

<html><head><style type=3D"text/css"><!-- DIV {margin:0px;} --></style></hea=
d><body><div style=3D"font-family:times new roman, new york, times, serif;fo=
nt-size:12pt"><DIV>LF,</DIV>
<DIV>I've nearly completed my new PA for 500 kHz and have now managed to</DI=
V>
<DIV>stop destroying FET's.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Unfortunately I have an unusual problem in that the heatsink cooling fa=
ns</DIV>
<DIV>are going U/S.</DIV>
<DIV>&nbsp;</DIV>
<DIV>I have used 24 volts brushless PC-type fans and after a while they</DIV=
>
<DIV>either die completely or start to go backwards slowly. . .</DIV>
<DIV>&nbsp;</DIV>
<DIV>The fans may be slightly over-run but only by a volt or so and on key-u=
p </DIV>
<DIV>(unregulated supply) and are situated about 50 mm (2 inches) from the h=
eatsink.</DIV>
<DIV>I have rf decoupled them from the supply but&nbsp;maybe not well enough=
 !</DIV>
<DIV>&nbsp;</DIV>
<DIV>Any suggestions&nbsp;in curing this problem would be most welcome.</DIV=
>
<DIV>&nbsp;</DIV>
<DIV>73 Chris G3XIZ</DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp;</DIV></div><br>



      </body></html>

--0-1177915108-1245479665=:74739--