Custom Cavity Filters DLI manufactures VHF cavity filters for use with our radio loggers.  We also build to your specifications. Airband RX filters covering the 108-137MHz VHF band are always in stock.  Typical insertion loss is less than 1dB at Fo. Notch filters are also available. Email Engineering@Digital-Loggers.com for more information, or call (408) 330-5507 now.