[Elecraft] OT: Anyone use a noise canceller?

[Mark Hampton]

Hi all, 
        I have a S-9 noise level across the bands and despite some detective work, I have been unable to locate the source.    

I feel that I may have to resort to using a noise canceller in order to use the bands at the home QTH.

Before I purchase one, I'm wondering if any of the subscribers to this list use one and if so, how effective are they?

Apologies for the off-topic post but I though I'd canvass opinions before I buy one.

Thanks, Mark M5MDH