[ARC5] Selectivity improvement in ARC-5 receivers.

[Bruce Long via ARC5]

No problem Ken
Only reason I remember this stuff is my day job requires me to design 2-3 filters every year.



________________________________
 From: Kenneth G. Gordon <kgordon2006 at frontier.com>
To: Bruce Long <coolbrucelong at yahoo.com> 
Cc: Arc5 at mailman.qth.net 
Sent: Monday, June 2, 2014 11:55 AM
Subject: Re: [ARC5] Selectivity improvement in ARC-5 receivers.
 

On 2 Jun 2014 at 6:32, Bruce Long wrote:




> The rejection slope (dB/octave) of a coupled bandpass filter does not depend
> upon the filter center frequency in Hz but rather by the offset frequency (
> distance from the filter center frequency) divided by the filter bandwidth.
> 
> Thus if you have a bandpass filter with a bandwidth of 10 kHz ( at any center
> frequency) and you are measuring the rejection at an offset frequency of 60 Khz
> ( ie 6 Octaves) you will be x dB down.

Thanks, Bruce.

My ancient memory banks have unused sections which are full of cobwebs 
and must be cleaned out once in a while. :-)

Ken W7EKB