David wrote:
On 26 Jul 2006 23:00:58 -0700, wrote:



It is an interesting idea, but nobody builds LCR filters. Rather, you
use the LCR filter as a prototype, then build a leapfrog active filter
from signal flow graphs based on the physical LCR filter.


Really? What kind of filters does the Drake R8 series use?

As a demod filter? I would image a low order active filter to clean
things up. Remember, this is the audio band, not RF. I've seen some
write ups on 455khz IFs being done with active filters.

Kiwa sells an active filter for 455Khz
http://www.kiwa.com/kiwa455.html

Note the AR7030 has "tone controls", so certainly it has an active
filter past the demod. The problem with building LCR filters in the
audio band is they are bulky, not to mention often inaccurate. With
active filters, you have more flexibility over component values.