I was looking through some old logs etc, and came across a short audio file with orban notch filter in and out (by passed)..

This file is on line in my logs for may 2010, but hidden deep in plain sight if you like in a mass of mw logs I had at the time..

the filter is here, bottom unit

https://www.dxarchive.com/mw/images/orban_642b.jpg

Below is a link to the audio file, testing the notch filter, in and out.... quite a difference....
I started copying a lot of airchecks from some of the old tapes, and then I never went back to it. 14 years ago!!! The notch filter is not even connected up just now. I must try and find the airchecks I have already copied.... and share....

https://www.dxarchive.com/mw/audio/790922_clip_orban_test_on_caroline_het.mp3

BTW Dave2, please dont destroy old radio stuff. Very collectable.