mm wrote:

On Fri, 05 Dec 2008 15:07:46 GMT, "TKM" 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?

The voltage from a multimeter, 9 volts usually, isn't going to hurt
anything, but I don't think you can expect a meaningful measurement
either.


What kind of meter are you using with 9 V between the probes? Ohm
meters are usually current limited, or constant current sdesigns.


There are semiconductors between the input and output of the
amplifier, and with no power, they might be acting as non-conductors.
Maybe I'm wrong about that, but how would you know if the resistance
is good or not, short of finding an identical antenna and measuring
it?

but suspect an open line going from the
lightning arrestor up the roof to the antenna.

So can't you disconnnect the cable at the antenna and measure the
resistance through the line with the arrestor only?

TKM



--
http://improve-usenet.org/index.html

aioe.org, Goggle Groups, and Web TV users must request to be white
listed, or I will not see your messages.

If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm


There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.