In reply to a post by lulubonkers:

I don't understand what you mean.

Sorry, didn't explain. There's low voltage DC coming into your home via VM's cable network. The isolator blocks RF below 2 MHz so prevents DC and any AC below 2 MHz frequency, cleaning up the signal and ensuring if you decide you really want to lick the conductor in the coax you don't get a tingle.

VM have a central power source for each group of however many hundred homes on the old cable network and coax carries the power to the amplifiers in cabinets. Some of it also ends up going down the drop to your home.

It's not a big deal but having isolators there to block that alongside DC and low frequency noise like the 240-ish Hz produced by our electricity supply is a good plan.

Please excuse my lateness in responding. I happened to have a look at this board and saw I hadn't.