If a DC power supply is needed near the antennas, the use of a coaxial cable for this purpose avoids pulling the additional cable to the roof or mast. The diagram below shows the DC power inserter – Power over Coaxial (PoC) solution tested by SP5GNI. Coupling capacitors should allow the transfer of relatively high current. The value of total capacity depends on the lowest operating frequency, 40 nF is enough for 160 m and higher bands.
The DC and AC voltage splitter can be placed in a small metal box with coaxial and DC sockets. I personally do not like too many devices on my desk, as well as additional connectors in the RF signal path, that’s why the “transmitting” part of the DC I built into the MFJ-993B antenna tuner at home, and the “receiving” part of DC to the antenna switch on the roof, as shown in the picture below.
The 13.8 V voltage on the roof is used to power the rotator motor, relays in the antenna switch, and to power the wireless WiFi antenna switch controller.