Combiners

[ShadowDelaware]

Why are port combiners not directly on the board. In example I noticed one amplifier builder removes the copper under where the port combiner will be placed, and noticed another uses a plastic insulator between the combiner and the board. What is the technical reason for doing this? I am very curious.

 

[nomadradio]

If you use enameled wire to wind a combiner, the insulation-breakdown voltage of the enamel might cause the RF voltage to arc if placed directly onto a grounded copper foil surface. Some folks use teflon-insulated wire. It has a higher breakdown voltage and probably doesn't need this extra step.

73