Wow, so much good info so quickly. Thanks Alex for pointing that out I figured that may have been the case and thanks Don for the info on the lines to look for too.
Don, is this the DGM NPB filter you mention? It has It seems to have additional peaks at 625 and 656. Is this too broad?
http://www.ebay.com.au/itm/NPB-2-0-D...#ht_482wt_1399