Message-ID: <4FEE1E65.405@iup.uni-heidelberg.de>
Date: Fri, 29 Jun 2012 23:30:13 +0200
From: =?UTF-8?B?U3RlZmFuIFNjaMOkZmVy?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: Fwd: Help needed, mechanical filters
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Hi Claudio, Mike, all,

In my tests i have connected 18 kOhm to the output, but no C. I tried=20
with a 220pF (was by hand) C but there was no change.
Mike's idea with the pot is good, of course.

On the output i measure with a high Z probe for the scope. But i don't=20
know the internal impedance of the signal generator. I put the 18 kOhm=20
in series to the signal generator but maybe i should simply play arround=20
with it, also with the Cs.

On the left side stands 300 pF, on the right side 294 pF. So this is the=20
load capacity that must be applied from external components?

These parts must be 50 years old or so. I find 3.95 Euro extremely cheap

Thanks for the advice. The first time i work with such a filter... It=20
should be fine for other applications as well, as a IF filter...


73, Stefan/DK7FC

Am 29.06.2012 22:59, schrieb Claudio Girardi:
> Stefan,
> if I understood correctly, the datasheet says that the impedance is 18=20
> kohm if you use the red and green wires and 500 ohm if you use the=20
> yellow and green ones; so you should load both sides with 18 kohm in=20
> your case, or change taps.
> Then you should also load the filter with the exact capacitance values=20
> printed on its ends, connected between the red and green wires.
>
> Regards,
>   Claudio
>
> On 06/29/2012 10:26 PM, Stefan Sch=C3=A4fer wrote:
>>
>> The input signal is connected on the left side between the red and gre=
en
>> wire. The output signal is taken from the right side on the red and
>> green wire too. It looks as if each side has a coil on the green and r=
ed
>> wire, with a tap at the yellow wire.
>> Helpful was this image from the web
>> http://www.amateurfunkmuseum.de/AFM_321b-Dateien/image006.jpg  which
>> shows a similar filter. I have connected a resistor of 18 kOhm to the
>> output and a 500 Ohm resistor in series to the signal generator, as
>> stated in the datasheet. But the ripple does not change.
>>
>> Any ideas or suggestions?
>>
>> Guess for what i will need the filter! :-)
>>
>> 73, Stefan/DK7FC
>>
>