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Re: LF: Fwd: Help needed, mechanical filters

To: [email protected]cksheep.org
Subject: Re: LF: Fwd: Help needed, mechanical filters
From: Stefan Schäfer <[email protected]>
Date: Fri, 29 Jun 2012 23:30:13 +0200
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Hi Claudio, Mike, all,

In my tests i have connected 18 kOhm to the output, but no C. I tried 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 know the internal impedance of the signal generator. I put the 18 kOhm in series to the signal generator but maybe i should simply play arround with it, also with the Cs.
On the left side stands 300 pF, on the right side 294 pF. So this is the
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 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 kohm if you use the red and green wires and 500 ohm if you use the yellow and green ones; so you should load both sides with 18 kohm in your case, or change taps. Then you should also load the filter with the exact capacitance values printed on its ends, connected between the red and green wires.
Regards,
  Claudio

On 06/29/2012 10:26 PM, Stefan Schäfer wrote:
The input signal is connected on the left side between the red and green
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 red
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


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