Kris, These filters are constant impedance designs so the transmitters unwanted sideband power gets dumped into a load on the Hybrid port. This also helps with group delay at edges of the filtered response.
... cant see why a ham would make a filter with twice as many cavities than needed, just to keep SWR low out of band.. The only possible use would be as a combiner for two repeater transmitters because one hybrid port acts as a wideband input. Problem is, if you are on 2m with two repeaters 60kHz apart each resonator has to be pass F1 and short F2. mange tout Ian G8PWE ----- Original Message ----- From: "Kris Kirby" <[email protected]> To: <[email protected]> Sent: Monday, February 22, 2010 6:21 PM Subject: [Repeater-Builder] Mask filters? > > In the commercial world of broadcasting, there is a hybrid filter used > called a mask filter. The mask filter is two -90 degree hybrids, a dummy > load, and a pair of bandpass cavities between them. They suppress > sidebands and keep the TV transmitter's radiation within the 6MHz > channel. > > Has anyone heard of a similar concept used for filtering amateur > repeaters? > > -- > Kris Kirby, KE4AHR > Disinformation Analyst > > > ------------------------------------ > > > > Yahoo! Groups Links > > >
