New (Secondhand that is,) band pass filter.

I have just won for £27, including postage, a six cavaty band pass filter.
I did a special event at a air show a couple of years ago where the licencee used a 2 meter band pass filter & have wanted one ever since, but I have been out bid by a couple of pounds on several, this time I got it.
I live VERY close to Norwich airport & that plus my liking for special event stations & a desire to be able to operate as safely as possible on all bands regadless of what I am operating close to means this, if it works is a great buy.
When we did the air show, it was at an old WWII USAF base & the air traffic control was via a handheld radio & the licence holder contacted both the PA operator & ATC to say this is who we are & if you have any problems then contact us & we will shut down imediatly as an act of good faith until we know it is not us.