Combiners

[Catalyst 122]

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

 

[Catalyst 122]

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

I use teflon, and the ones I've seen either etch the board or use a spacer used teflon also. It makes perfect sense if you're using enamelled wire.... I guess you just can't be too safe. Thank you for the reply.

 

[linearone]

Plus it adds capacitance to the circuit which fucks it up for various reasons. It can couple in some cases and to the uninitiated can rock their world. same thing happens when guys mount a filament choke to the chassis.

 

[linearone]

Speaking of filament chokes, not that this is my thread, but on the same vein of thought... I learned the coupling effect to the chassis the hard way. I pretty much suspend every filament choke now just off the surface of the deck. However you can do it is useful...in tube amps of course.