The GB7ZP UHF Repeater Duplexer consisted of a Procom Cavity set (below) supplemented by a Procom BPF70/3 bandpass filter on the 439.4875 MHz transmitter output. Click for alternate views: small, large The original implementation had poor screening and sensitivity - pictures below show the early upgrades on coax and extra preamp. In 2024 the filtering was extracted to create the Current GBZP Duplexer in its own 1U rack case. Before in 2008, Modified in 2010