> > Filter Number TT Item # Filter BW > > > > 526-8733-010 = 2032 300Hz > > 526-8693-010 = 2031 500Hz > > 526-8694-010 = stock 2.5kHz > > > Those last three sure look like Collins part numbers? 455 KHz mechanical filters for Orion > or Omni VII? Orion has 450Khz ceramic filters in lieu of 455Khz mechanical or xtal filters. 73, Barry N1EU