PolyPhasor does provide models that pass DC.
We use them at our tower sites to protect the lines that connect to
our Tower Mounted Amplifiers. We have a band-specific preamp installed
at the top of the tower to which an antenna is connected for receive
only. That antenna is always at the highest point on our towers. DC to
power the preamp comes up from a power supply in the shelter through a
PolyPhaser mounted on the grounding plate inside the shelter through
the 7/8 inch feedline to the box at the top. Works well and survives
direct lightning strikes many times a year.
Our shelters employ interior and exterior "Cadwelded" heavy stranded
copper wire "halos" with everything inside and outside the shelter
bonded together. The exterior ground "ring" is buried several feet
below grade with heavy "jumpers" exiting the shelter 2 or 3 times
along each exterior wall. The tower and all related exterior items are
bonded to the exterior ring as well. All feedlines and control lines
coming through the walls are protected by a PolyPhaser of the correct
type. Inside the shelter, a similarly heavy stranded copper "halo"
runs around the ceiling and everything inside the shelter is bonded to
that ring. It ain't cheap but it works very well. We RARELY ever have
any issues caused by lightning.
Of course, some of our sites are served by other vendors or carriers
who are not as ambitious about lightning protection so we suffer loss
of service because of lightning damage to their facilities. But that's
another matter.
I know several hams here in the Lightning Belt of Florida who have
kinda, sorta duplicated this type of professional grounding scheme.
They have never had any problems with lightning strikes direct or
otherwise. You get what you pay for.
73,
Frank N. Haas KB4T
Utility Interference Investigator
Florida
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