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Date: Thu, 08 Mar 2012 21:51:29 +0100
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Short burst of DK7FC on 137
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Hello John, LF,

Thanks to Steinar/LA5VNA who kindly gave me the hint to a free program=20
to draw schematics on the PC (http://www.expresspcb.com/index.htm),=20
which works very well and intuitive.

Now i have now created the circuit of the exciter of my LF PA, as=20
promised. Here it is:=20
http://dl.dropbox.com/u/19882028/LF/LF%20H%20bridge%20PA%20Exciter%2C%20D=
K7FC.jpg
This is what i'm running here during the last months.

I will also create the schematic for the rest of the PA including the=20
complete H bridge configuration and LPF and publish that here, in a few=20
days.

73, fun, Stefan/DK7FC

Am 05.03.2012 09:28, schrieb John Rabson:
> Thank you Stefan.
>
> These pictures are very helpful. I look forward to seeing the exciter i=
nformation.
>
> 73
> John F5VLF
>
> On 4 Mar 2012, at 14:22CET, Stefan Sch=E4fer wrote:
>
>   =20
>> Hi John,
>>
>> Am 04.03.2012 13:35, schrieb John Rabson:
>>     =20
>>> 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, plea=
se? I am finding that I am rather good at blowing up class E PAs and thin=
k I should look for something that is rather more robust (and more tolera=
nt of variations in load isimpedance).
>>>       =20
>> Well i have done some drawings and pictures in the last time, concerni=
ng my PA and LPF and matching system.
>> Here they are:
>> http://dl.dropbox.com/u/19882028/LF/DK7FC_137kHz_TX_antenna_and_PA_sch=
ematic.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 wee=
k. Pse ask me agn if i forget it.
>>
>> BTW the blue output transformer in the photo handles at least 1.5 kW C=
W 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/D=
atenbl%C3%A4tter/B64290L699X830.pdf (page 3)
>> Available e.g. @ https://www.buerklin.com/default.asp?event=3DShowArti=
kel(84D258)&l=3Dd&jump=3DArtNr_84D258 for 10 Euro :-)
>>
>> 73, Stefan/DK7FC
>>
>>
>>     =20
>
>   =20