Does coax have a shelf life?

I was rummaging around my father's garage the other day and came across a
roll of URM43 that I know to be over 20 years old. It looks OK and the
copper is shiny. However, can I be confident that it will not have lost any
of its electrical or physical properties? I intend to take it on holiday
with me soon and don't want it to fail.

Advice please!!

Thanks
John/G4IRN

"John" wrote in message
...
Does coax have a shelf life?

I was rummaging around my father's garage the other day and came across a
roll of URM43 that I know to be over 20 years old. It looks OK and the
copper is shiny. However, can I be confident that it will not have lost
any
of its electrical or physical properties? I intend to take it on holiday
with me soon and don't want it to fail.

Advice please!!

Thanks
John/G4IRN


as long as it was kept dry and not exposed to excessive heat or chemicals
(oil or gasoline in a garage) it should be ok. give it a good flexing and
check end to end to be sure the jacket isn't cracked. a quick electrical
test is to hook it up to a dummy load, transmit on the highest frequency
band you can and measure the power in and out (if you only have one meter
you can make two separate measurements). as long as you aren't loosing too
much it should be fine.

John wrote:

Does coax have a shelf life?

I was rummaging around my father's garage the other day and came across a
roll of URM43 that I know to be over 20 years old. It looks OK and the
copper is shiny. However, can I be confident that it will not have lost any
of its electrical or physical properties? I intend to take it on holiday
with me soon and don't want it to fail.

Advice please!!

Thanks
John/G4IRN

I've never had new coax in fourty five years of hamming! I get old
stuff at flea markets or wherever and have used it with great success!
--
--------------------------------------
Diagnosed Type II Diabetes March 5 2001
Beating it with diet and exercise!
297/215/210 (to be revised lower)
58"/43"(!)/44" (already lower too!)
--------------------------------------
Visit my HomePage at http://members.shaw.ca/finkirv/
Visit my very special website at http://members.shaw.ca/finkirv4/
Visit my CFSRS/CFIOG ONLINE OLDTIMERS website at http://members.shaw.ca/finkirv5/
--------------------
Irv Finkleman,
Grampa/Ex-Navy/Old Fart/Ham Radio VE6BP
Calgary, Alberta, Canada

Chop off 3 or 4 feet from both the ends and throw the ends out. Also
check the outer jacket for nicks and cracks. Any nick or crack will
let moisture in and cause problems. Most problems with older cable
will be from moisture seeping into the cable from the ends or through
nicks and cracks in the outer jacket. Do the cutting even if it has
connectors on it because most connectors especially PL-259 type are
not moisture resistant. Also look for places the cable has been
crushed, kinked or flattened. These will be bad spots. I've
successfully used 20 year old cable many times.

On Sat, 9 Aug 2003 11:11:45 +0100, "John" wrote:

Does coax have a shelf life?

I was rummaging around my father's garage the other day and came across a
roll of URM43 that I know to be over 20 years old. It looks OK and the
copper is shiny. However, can I be confident that it will not have lost any
of its electrical or physical properties? I intend to take it on holiday
with me soon and don't want it to fail.

Advice please!!

Thanks
John/G4IRN

"John" wrote in message ...
Does coax have a shelf life?

I was rummaging around my father's garage the other day and came across a
roll of URM43 that I know to be over 20 years old. It looks OK and the
copper is shiny. However, can I be confident that it will not have lost any
of its electrical or physical properties?

1) Build, beg, borrow or buy a decent wattmeter and dummy load of the
characteristic Z of the cable.

2) Connect the output of your rig to the dummy load through the cable
to be tested. Put the wattmeter between the rig and cable to be
tested. Measure power on the highest band.

3) Move the wattmeter so that it is between the cable to be tested and
the dummy load. Measure power on the highest band (don't change
anything else!)

Difference is loss at the highest band when matched. A little math
will give you the answer in dBs.

73 de Jim, N2EY