Coax Query
 

I have been using Belden 9913 RG-8U solid core for the past 7 years.
Its used with a Jogunn 5+5 beam and Yaesu rotor. Will this stand up for
another 10+ years or ditch it for some low loss, stranded, foam or
non-contaminating coax?

In , jim wrote:

I have been using Belden 9913 RG-8U solid core for the past 7 years.
Its used with a Jogunn 5+5 beam and Yaesu rotor. Will this stand up for
another 10+ years or ditch it for some low loss, stranded, foam or
non-contaminating coax?


Used coax can be tested on the bench for characteristic impedance, dielectric
integrity, DC resistance, and even for pinholes in the outer insulation. But
unless you measured these factors when new, you can't make a good determination
of its quality after several years of use. The problem is that your average coax
isn't hermetically sealed, so moisture will eventually seep in and slowly
corrode the conductors. Weaknesses in the outer insulation (due to age, oil
contamination, mechanical stresses and manufacturing imperfections) cause
microscopic pinholes that make the corrosion process go faster. It's best to
replace your coax periodically. I would say that seven years is plenty long
enough for an outside line.

Now I can't stress this enough: -=DON'T USE FOAM=-!!! There are several reasons
not to use foam. First, foam coax is very porous and is intended for controlled
environments where there is little variation in temperature and humidity, the
factors primarily responsible for moisture seeping into the coax. Second, the
dielectric softens with just mild heat, and the line could be ruined by nothing
more than a hot sunny day. Also, the foam doesn't have the mechanical strength
to handle the stresses of being clamped to an antenna and hung from any decent
height, not to mention the repeated movements caused by wind, or the expansion
and contraction caused by wide temperature changes. For antenna installations,
foam coax is -BAD NEWS-!

As far as solid vs. stranded is concerned, the only real advantage of solid is a
higher usable frequency (we're talking GHz here). Stranded conductors offer more
flexibility, which is important when the coax is constantly under the mechanical
stresses of an antenna installation.

The only other thing you may want to know about any type of coax is how flexible
it will be when the weather turns cold. In that respect, I have yet to find any
coax that fills the bill.







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"jim" wrote in message
...
I have been using Belden 9913 RG-8U solid core for the past 7 years.
Its used with a Jogunn 5+5 beam and Yaesu rotor. Will this stand up for
another 10+ years or ditch it for some low loss, stranded, foam or
non-contaminating coax?


Hi Jim Carroll, nice to hear from you!
I have always just replaced my coax every 8
to 10 years no matter what. I figure between
the use of millions of watts, wind, rain, ice, heat,
birds, low flying planes, it should just be replaced
for the old age aspect.

Landshark


--
Treat people as if they were what
they ought to be and you will help
them become what they are capable
of becoming.

"Frank Gilliland" wrote in message
...
In , jim wrote:

I have been using Belden 9913 RG-8U solid core for the past 7 years.
Its used with a Jogunn 5+5 beam and Yaesu rotor. Will this stand up for
another 10+ years or ditch it for some low loss, stranded, foam or
non-contaminating coax?


Used coax can be tested on the bench for characteristic impedance,
dielectric
integrity, DC resistance, and even for pinholes in the outer insulation.
But
unless you measured these factors when new, you can't make a good
determination
of its quality after several years of use. The problem is that your
average coax
isn't hermetically sealed, so moisture will eventually seep in and slowly
corrode the conductors. Weaknesses in the outer insulation (due to age,
oil
contamination, mechanical stresses and manufacturing imperfections) cause
microscopic pinholes that make the corrosion process go faster. It's best
to
replace your coax periodically. I would say that seven years is plenty
long
enough for an outside line.

Now I can't stress this enough: -=DON'T USE FOAM=-!!! There are several
reasons
not to use foam. First, foam coax is very porous and is intended for
controlled
environments where there is little variation in temperature and humidity,
the
factors primarily responsible for moisture seeping into the coax. Second,
the
dielectric softens with just mild heat, and the line could be ruined by
nothing
more than a hot sunny day. Also, the foam doesn't have the mechanical
strength
to handle the stresses of being clamped to an antenna and hung from any
decent
height, not to mention the repeated movements caused by wind, or the
expansion
and contraction caused by wide temperature changes. For antenna
installations,
foam coax is -BAD NEWS-!

As far as solid vs. stranded is concerned, the only real advantage of
solid is a
higher usable frequency (we're talking GHz here). Stranded conductors
offer more
flexibility, which is important when the coax is constantly under the
mechanical
stresses of an antenna installation.

The only other thing you may want to know about any type of coax is how
flexible
it will be when the weather turns cold. In that respect, I have yet to
find any
coax that fills the bill.







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Excellent answer! My only addition is (and correct me if I'm wrong)
electrons follow the surface of the wire and stranded wire offers more
surface area than solid wire.

--
visit http://www.geocities.com/linearschematics/

"Dr. Death" wrote in message
...
snip
Excellent answer! My only addition is (and correct me if I'm wrong)
electrons follow the surface of the wire and stranded wire offers more
surface area than solid wire.


At 11-meter frequencies it doesn't matter if you use stranded or solid
unless you are going hundreds of feet. Stranded coax is a bit more flexible
and forgiving of kinks. When you get into the UHF and microwave frequencies
then you should use coax with a solid center conductor, as Frank said.

Here's a tip that helps me with the cold weather problem of coax that needs
to flex. Use your high quality coax for the long run from your rig to the
base of your antenna, I use LMR-400. Run a short piece of RG-8x from the
base of the rotor to the connection on your antenna. You will need to
replace it every few years but it's cheep and a length of 10 or so feet
isn't going to give you much, if any measurable loss on 11-meters.

Kevin, WB5RUE




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In , "Kevin Muenzler, WB5RUE"
wrote:


"Dr. Death" wrote in message
...
snip
Excellent answer! My only addition is (and correct me if I'm wrong)
electrons follow the surface of the wire and stranded wire offers more
surface area than solid wire.


At 11-meter frequencies it doesn't matter if you use stranded or solid
unless you are going hundreds of feet. Stranded coax is a bit more flexible
and forgiving of kinks. When you get into the UHF and microwave frequencies
then you should use coax with a solid center conductor, as Frank said.


Bingo.


Here's a tip that helps me with the cold weather problem of coax that needs
to flex. Use your high quality coax for the long run from your rig to the
base of your antenna, I use LMR-400. Run a short piece of RG-8x from the
base of the rotor to the connection on your antenna. You will need to
replace it every few years but it's cheep and a length of 10 or so feet
isn't going to give you much, if any measurable loss on 11-meters.


Good idea. It also provides a convenient break in the run to install a grounding
block.






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"Frank Gilliland" wrote in message
...
In , "Kevin Muenzler, WB5RUE"

wrote:

Here's a tip that helps me with the cold weather problem of coax that
needs
to flex. Use your high quality coax for the long run from your rig to
the
base of your antenna, I use LMR-400. Run a short piece of RG-8x from the
base of the rotor to the connection on your antenna. You will need to
replace it every few years but it's cheep and a length of 10 or so feet
isn't going to give you much, if any measurable loss on 11-meters.


Good idea. It also provides a convenient break in the run to install a
grounding
block.


Actually if you install a grounding block and lightning hits you replace
your coax, your antenna and a grounding block. They don't do squat. Most
antennas are at DC ground anyway so ground your entire system not just the
coax. Of course if you are using a dipole you should be using a BALUN and
most come with a ground connection. DON'T expect it to save your radio in
the event of a direct (or close) strike. You are looking at hundreds of
millions of volts at hundreds of thousands of amps. That little grounding
block is going to vaporize along with your coax. If you want real
protection visit poliphaser. They have excellent stuff (at more than
"excellent" prices). Don't buy the $20 grounding blocks and expect
protection.

Kevin, WB5RUE




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In , "Kevin Muenzler, WB5RUE"
wrote:


"Frank Gilliland" wrote in message
.. .
In , "Kevin Muenzler, WB5RUE"

wrote:

Here's a tip that helps me with the cold weather problem of coax that
needs
to flex. Use your high quality coax for the long run from your rig to
the
base of your antenna, I use LMR-400. Run a short piece of RG-8x from the
base of the rotor to the connection on your antenna. You will need to
replace it every few years but it's cheep and a length of 10 or so feet
isn't going to give you much, if any measurable loss on 11-meters.


Good idea. It also provides a convenient break in the run to install a
grounding
block.


Actually if you install a grounding block and lightning hits you replace
your coax, your antenna and a grounding block. They don't do squat. Most
antennas are at DC ground anyway so ground your entire system not just the
coax. Of course if you are using a dipole you should be using a BALUN and
most come with a ground connection. DON'T expect it to save your radio in
the event of a direct (or close) strike. You are looking at hundreds of
millions of volts at hundreds of thousands of amps. That little grounding
block is going to vaporize along with your coax. If you want real
protection visit poliphaser. They have excellent stuff (at more than
"excellent" prices). Don't buy the $20 grounding blocks and expect
protection.

Kevin, WB5RUE



Did you miss the recent thread on this subject?







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"Frank Gilliland" wrote in message
...
In , "Kevin Muenzler, WB5RUE"

wrote:


"Frank Gilliland" wrote in message
.. .
In , "Kevin Muenzler, WB5RUE"

wrote:

Here's a tip that helps me with the cold weather problem of coax that
needs
to flex. Use your high quality coax for the long run from your rig to
the
base of your antenna, I use LMR-400. Run a short piece of RG-8x from
the
base of the rotor to the connection on your antenna. You will need to
replace it every few years but it's cheep and a length of 10 or so
feet
isn't going to give you much, if any measurable loss on 11-meters.


Good idea. It also provides a convenient break in the run to install a
grounding
block.


Actually if you install a grounding block and lightning hits you replace
your coax, your antenna and a grounding block. They don't do squat.
Most
antennas are at DC ground anyway so ground your entire system not just
the
coax. Of course if you are using a dipole you should be using a BALUN
and
most come with a ground connection. DON'T expect it to save your radio
in
the event of a direct (or close) strike. You are looking at hundreds of
millions of volts at hundreds of thousands of amps. That little
grounding
block is going to vaporize along with your coax. If you want real
protection visit poliphaser. They have excellent stuff (at more than
"excellent" prices). Don't buy the $20 grounding blocks and expect
protection.

Kevin, WB5RUE



Did you miss the recent thread on this subject?


Must have, what was the title?




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In , "Kevin Muenzler, WB5RUE"
wrote:


"Frank Gilliland" wrote in message
.. .
snip
Did you miss the recent thread on this subject?


Must have, what was the title?


CB station grounding






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"Frank Gilliland" wrote in message
...
In , "Kevin Muenzler, WB5RUE"

wrote:


"Frank Gilliland" wrote in message
.. .
snip
Did you miss the recent thread on this subject?


Must have, what was the title?


CB station grounding

That one went to trash after about five so I missed 90% of the conversation.




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In , "Kevin Muenzler, WB5RUE"
wrote:


"Frank Gilliland" wrote in message
.. .
In , "Kevin Muenzler, WB5RUE"

wrote:


"Frank Gilliland" wrote in message
.. .
snip
Did you miss the recent thread on this subject?


Must have, what was the title?


CB station grounding

That one went to trash after about five so I missed 90% of the conversation.


That's probably a good thing. The point was that there is no 'good' method to
protect against lighting except to unplug. Some loudmouth wannabe was trying to
pass off the idea that you can leave your equipment connected, even the coax, as
long as the house has a central grounding point. I'm betting that he works for
some company that reaps the benefits of lightning damage......







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"Frank Gilliland" wrote in message
...
In , "Kevin Muenzler, WB5RUE"

wrote:


"Frank Gilliland" wrote in message
.. .
In , "Kevin Muenzler, WB5RUE"

wrote:


"Frank Gilliland" wrote in message
.. .
snip
Did you miss the recent thread on this subject?


Must have, what was the title?


CB station grounding

That one went to trash after about five so I missed 90% of the
conversation.


That's probably a good thing. The point was that there is no 'good' method
to
protect against lighting except to unplug. Some loudmouth wannabe was
trying to
pass off the idea that you can leave your equipment connected, even the
coax, as
long as the house has a central grounding point. I'm betting that he works
for
some company that reaps the benefits of lightning damage......


I wonder how many time he's actually been struck? How many times he's had
to file insurance claims for fire damage?

There IS equipment that will protect against a direct strike, he's right on
that account. But you're going to pay more than it cost for his equipment
to have it installed. There's a company here in south Texas that does that
sort of thing. I live on a hill so I contacted them and asked them to give
me a quote for tower protection. It was going to cost me $49k for them to
protect and guarantee my tower and equipment against damage in the event a
direct strike. This didn't include a $1200/year "maintenance fee." I did
have them install grounding and protection on my house, the little spike
things on the corners and peak of the roof. That was respectable, only
$3000 but I got a nice break on my insurance costs that paid for it in about
three years. My house has never taken a direct strike but my tower gets
struck at least once a year. I should own stock in Belden!

Kevin, WB5RUE




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In , "dude!" wrote:


"Frank Gilliland" wrote in message
.. .
In , "Kevin Muenzler, WB5RUE"

wrote:


"Frank Gilliland" wrote in message
.. .
In , "Kevin Muenzler, WB5RUE"

wrote:


"Frank Gilliland" wrote in message
.. .
snip
Did you miss the recent thread on this subject?


Must have, what was the title?


CB station grounding

That one went to trash after about five so I missed 90% of the
conversation.


That's probably a good thing. The point was that there is no 'good' method
to
protect against lighting except to unplug. Some loudmouth wannabe was
trying to
pass off the idea that you can leave your equipment connected, even the
coax, as
long as the house has a central grounding point. I'm betting that he works
for
some company that reaps the benefits of lightning damage......


I wonder how many time he's actually been struck? How many times he's had
to file insurance claims for fire damage?

There IS equipment that will protect against a direct strike, he's right on
that account. But you're going to pay more than it cost for his equipment
to have it installed. There's a company here in south Texas that does that
sort of thing. I live on a hill so I contacted them and asked them to give
me a quote for tower protection. It was going to cost me $49k for them to
protect and guarantee my tower and equipment against damage in the event a
direct strike. This didn't include a $1200/year "maintenance fee."


Judas 'Flippin' H. Priest.... those are commercial rates!!!


I did
have them install grounding and protection on my house, the little spike
things on the corners and peak of the roof. That was respectable, only
$3000 but I got a nice break on my insurance costs that paid for it in about
three years. My house has never taken a direct strike but my tower gets
struck at least once a year. I should own stock in Belden!


Heck, you can do it yourself for a LOT less -- in fact, most of the stuff you
can find at your local junkyard. Just drop me an email when you are ready, then
give me a few days to draw up some diags in CAD.







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"Frank Gilliland" wrote in message
...
In , "dude!" wrote:


I did
have them install grounding and protection on my house, the little spike
things on the corners and peak of the roof. That was respectable, only
$3000 but I got a nice break on my insurance costs that paid for it in
about
three years. My house has never taken a direct strike but my tower gets
struck at least once a year. I should own stock in Belden!


Heck, you can do it yourself for a LOT less -- in fact, most of the stuff
you
can find at your local junkyard. Just drop me an email when you are ready,
then
give me a few days to draw up some diags in CAD.

Yes but in this case if I take damage THEY cover the cost that the insurance
doesn't.




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