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Re: LF: Sound Card mic Impedance

from [Andy Talbot] [Permanent Link][Original]
To: [email protected]
Subject: Re: LF: Sound Card mic Impedance
From: Andy Talbot <[email protected]>
Date: Thu, 16 Dec 2010 20:25:17 +0000
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If its a passive L/C filter, why not do a version with unequal Zin and Zout and take advantage of the voltage gain in going from 50ohms to, say, 500 ohms?   That will give you an apparant 10dB without trying.
 
AADE filter designer lets you have different termination impedances.
 
Andy
 


 
On 16 December 2010 20:06, Ken <[email protected]> wrote:
Thank you all LFs.
Thank you for all the info that you sent me, it looks they can be anything from 4k ohms upwards, this is ok for me, I am doing  a Low Pass Filter to use with Winrad, F1, 20kHz, F2, 30 kHz, 100kHz -80 dB (theoretical) with a characteristic impedance of 50 ohms, with this high input impedance I can locate the filter very close to the sound card mic input and terminate the filter output with a 50 ohm resistor. Hopefully this will eliminate the BC intermod I was experiencing when trying to receive Chris G3XIZ the other day.
 
73
Ken
M0KHW   I091TV 

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