UCLAN wrote:
mm wrote:

Who knows if it's OK to measure the resistance (using a standard
multimeter) of a coax line connected to an amplified antenna after
disconnecting the amplifier power supply, but not the antenna. I'm
concerned about damaging the amplifier inside the antenna,

You want to measure the resistance of the center conductor, right?

Easy to connect to the coax, but what do you want to connect to at the
other end? The rods that stick out of the antenna?

It's easy to test coaxial cable, no matter the length. Simply screw on a
75 ohm termination cap at one end, and measure from center conductor to the
ground shield at the other end. The ohmmeter will read 75 ohms plus
whatever
the impedance of the cable is.

Reword " plus the impedance of the cable is" to "plus the DC resistance
of the is" and you will be correct.

Measure the resistance of the terminator just in case, as I've seen some
that were 91 ohms....

If you see a run of cable that adds more than 10 ohms to the terminator
resistance, suspect a bad run of cable or corrosion at the connectors.

Just remember that DC continuity of coax is just that. Bad or lossy
cable can still show good continuity.