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From: John Rabson <john.rabson@numeo.fr>
In-Reply-To: <4F536CA6.6050702@iup.uni-heidelberg.de>
Date: Mon, 5 Mar 2012 09:28:28 +0100
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To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Short burst of DK7FC on 137
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Thank you Stefan.

These pictures are very helpful. I look forward to seeing the exciter =
information.

73
John F5VLF

On 4 Mar 2012, at 14:22CET, Stefan Sch=E4fer wrote:

> Hi John,
>=20
> Am 04.03.2012 13:35, schrieb John Rabson:
>> You recently mentioned that you were using an H-Bridge amplifier for =
137, but I seem to have lost the details. Could you post them again, =
please? I am finding that I am rather good at blowing up class E PAs and =
think I should look for something that is rather more robust (and more =
tolerant of variations in load isimpedance).
>=20
> Well i have done some drawings and pictures in the last time, =
concerning my PA and LPF and matching system.
> Here they are:
> =
http://dl.dropbox.com/u/19882028/LF/DK7FC_137kHz_TX_antenna_and_PA_schemat=
ic.jpg
> http://dl.dropbox.com/u/19882028/LF/PA%20output%20filter.jpg
> Hm, sorry i'm missing the photo of the drawing of the exciter. I know =
i have it on a sheet but maybe i forgot to scan it. Will so that next =
week. Pse ask me agn if i forget it.
>=20
> BTW the blue output transformer in the photo handles at least 1.5 kW =
CW at 137 kHz. Usually if people ask what type of ferrite is used in a =
PA, the answer is like "it is taken from a SMPS or old TV and unknown =
origin", "found it in the junkbox"... But here i know the exact type and =
even a distributor and even the price! ;-) It is even avaialable in =
quantity =3D 1 :-)
> It is a B64290L0699X830. Datasheet: =
http://dl.dropbox.com/u/19882028/Datenbl%C3%A4tter/B64290L699X830.pdf =
(page 3)
> Available e.g. @ =
https://www.buerklin.com/default.asp?event=3DShowArtikel(84D258)&l=3Dd&jum=
p=3DArtNr_84D258 for 10 Euro :-)
>=20
> 73, Stefan/DK7FC
>=20
>=20