I want to distribute output from a modulator (UHF channels) though the DPP44 switch to my 4 satellite receivers. Can I use the 4th input port? Would I use a Holland DPD2 diplexer? The output from a 1000.4WA dish is also going into the DPP44 switch.
IIRC the DPP44 does not pass those frequencies. (And oh by the way your Dish receivers can't use them anyhow. Presume you meant TV receivers.) So you are going to need 8 DPD2 diplexers not to mention a 3 way splitter.