For an interesting thread see:
http://amfone.net/Amforum/index.php?topic=3857.0

Terry

Yea, those guys over there got a lot on the ball with High Perfromance
detectors and such. Frank, GFZ, is a friend of mine and does a lot
with the Racal units.

I'm not looking for anybody to do any hands on work that will take up a
lot of time. Just a few who I can bounce Ideas off of and help if I
get stuck. Like I said - I'm in between jobs so I got the time to lay
out a board. When boards done whoever wants one can have.

Looks like the board will have the detector, amplifier and filter on
it. I want to drive a set of phones with the thing and am not really
too concerned with driving a speaker. I will have a line out connector
to drive directly into my Marantz so I don't think amplifier will be so
critical for me. I notice that Dallas Lankford set up his filters to
drive into 8 ohms. I think I'm going to drive into a higher impedance
- probably near 100 ohms and then just a buffer to drive the phones.

So question for now is about headphone impedance. I'll post that
seperate and see what others are using for phones.

Below is link to paper. it's the one about improved eliptic filters.
I have the filters in switchercad just to see how impedance effects
filter response.

http://www.kongsfjord.no/dl/dl.htm

73
NEO