Unkinking Coax
 

I have a length of rg-58/u which was rolled up and when unrolled has
revealed some kinks. Has anyone any idea on how to smooth things out
again. It shows good on my analyzer, and I'm not worried about a bit
of migration which may have taken place. A bit of loss is of no real
concern to me. Someone suggested letting it rest in a tub of hot water
for a while, but that is the only suggestion so far.

Thanks in advance for any assistance,

Irv VE6BP

Unkinking Coax
 

On 10/18/2014 9:28 AM, Irv Finkleman VE6BP wrote:
I have a length of rg-58/u which was rolled up and when unrolled has
revealed some kinks. Has anyone any idea on how to smooth things out
again. It shows good on my analyzer, and I'm not worried about a bit
of migration which may have taken place. A bit of loss is of no real
concern to me. Someone suggested letting it rest in a tub of hot water
for a while, but that is the only suggestion so far.

Thanks in advance for any assistance,

Irv VE6BP

My first suggestion is to lay it in the midday sun an allow it to warm
for an hour or more. Then uncoil it and allow it to relax a bit longer.

My garden hose responds to that treatment.

Good luck.

John

Unkinking Coax
 

On Sat, 18 Oct 2014 08:28:26 -0600, Irv Finkleman VE6BP
wrote:

I have a length of rg-58/u which was rolled up and when unrolled has
revealed some kinks. Has anyone any idea on how to smooth things out
again. It shows good on my analyzer, and I'm not worried about a bit
of migration which may have taken place. A bit of loss is of no real
concern to me. Someone suggested letting it rest in a tub of hot water
for a while, but that is the only suggestion so far.

As long as the kinks are only in the outer jacket, I wouldn't worry
about it. However, if it appears that the braid is also kinked or
wrinkled, you might be right about the center wire migration. If you
have a TDR (time domain reflectometer), it will show an impedance bump
where the center wire has moved. Such cold flow tends to happen with
RG-58a/u solid center conductor cable and low loss foam dielectric.
I've only seen it once and you have to roll it into a really small
tight coil before that will happen. It also requires rigidly attached
coax connectors to produce migration. (Open coax ends just cause the
center wire to telescope in and out).

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Unkinking Coax
 

"Irv Finkleman VE6BP" wrote in message
...
I have a length of rg-58/u which was rolled up and when unrolled has
revealed some kinks. Has anyone any idea on how to smooth things out
again. It shows good on my analyzer, and I'm not worried about a bit
of migration which may have taken place. A bit of loss is of no real
concern to me. Someone suggested letting it rest in a tub of hot water
for a while, but that is the only suggestion so far.

Go up to the kink, and treating it as though it is still rolled around the
former, unroll it.

Unkinking Coax
 

On Sat, 18 Oct 2014 18:41:24 +0100, gareth wrote:

"Irv Finkleman VE6BP" wrote in message
...
I have a length of rg-58/u which was rolled up and when unrolled has
revealed some kinks. Has anyone any idea on how to smooth things out
again. It shows good on my analyzer, and I'm not worried about a bit
of migration which may have taken place. A bit of loss is of no real
concern to me. Someone suggested letting it rest in a tub of hot water
for a while, but that is the only suggestion so far.

Go up to the kink, and treating it as though it is still rolled around
the former, unroll it.

Once unrolled as to unwind any kink, stretch the length of coax between
two supports for a few days and allow the sag to stretch the coax back.

Unkinking Coax - FINAL RESULTS ARE IN!
 

Irv Finkleman VE6BP wrote:
I have a length of rg-58/u which was rolled up and when unrolled has
revealed some kinks. Has anyone any idea on how to smooth things out
again. It shows good on my analyzer, and I'm not worried about a bit
of migration which may have taken place. A bit of loss is of no real
concern to me. Someone suggested letting it rest in a tub of hot water
for a while, but that is the only suggestion so far.

Thanks in advance for any assistance,

Irv VE6BP

OK guys, thanks for the input.
First a couple comments -- my 'yard' is a 6x10 foot third floor deck and
the yard is not accessible. I could not use the deck only because it
faces south and the apparent movement of the sun across the sky leaves
different and changing portions in the shade.

I wasn't worried about a leaking coax as it looked quite new, and
tested good on my MFK-259 Analyzer.

I decided that all factors considered I would give it a good soaking
in hot water in the sink, changed frequently to keep it hot. The
cable ends were kept out of the water.

I kept the water hot for 6 hours or so, and the cable came out feeling
quite supple and appearing kink free. It lay on the floor like wert
spaghetti, and it still tests good on the analyzer.

It's only a short length -- maybe 25 ft with PL-259s on the end, and
it was given to me free, so could easily have gone and bought some,
but ham radio is ham radio, and free coax with fittings is always
welcome. Now I can store it away properly coiled so that if I ever
do need it, it won't be a problem. Murphy (of Murphy's Laws), who lives
with me, tells me I'll never need it again in 100 years!

I guess it it had been an RG-8 variety, I would have had to use the
bathtub!

Thanks again all, it was an interesting experiment.

Irv VE6BP

Unkinking Coax - FINAL RESULTS ARE IN!
 

"Irv Finkleman VE6BP" wrote in message
...

Irv Finkleman VE6BP wrote:
I have a length of rg-58/u which was rolled up and when unrolled has
revealed some kinks. Has anyone any idea on how to smooth things out
again. It shows good on my analyzer, and I'm not worried about a bit
of migration which may have taken place. A bit of loss is of no real
concern to me. Someone suggested letting it rest in a tub of hot water
for a while, but that is the only suggestion so far.

Thanks in advance for any assistance,

Irv VE6BP

OK guys, thanks for the input.
First a couple comments -- my 'yard' is a 6x10 foot third floor deck and
the yard is not accessible. I could not use the deck only because it
faces south and the apparent movement of the sun across the sky leaves
different and changing portions in the shade.

I wasn't worried about a leaking coax as it looked quite new, and
tested good on my MFK-259 Analyzer.

I decided that all factors considered I would give it a good soaking
in hot water in the sink, changed frequently to keep it hot. The
cable ends were kept out of the water.

I kept the water hot for 6 hours or so, and the cable came out feeling
quite supple and appearing kink free. It lay on the floor like wert
spaghetti, and it still tests good on the analyzer.

It's only a short length -- maybe 25 ft with PL-259s on the end, and
it was given to me free, so could easily have gone and bought some,
but ham radio is ham radio, and free coax with fittings is always
welcome. Now I can store it away properly coiled so that if I ever
do need it, it won't be a problem. Murphy (of Murphy's Laws), who lives
with me, tells me I'll never need it again in 100 years!

I guess it it had been an RG-8 variety, I would have had to use the
bathtub!

Thanks again all, it was an interesting experiment.

Irv VE6BP
^^^^^^^^^^^^^^^^

Glad it worked out for you Irv. And I hope you are getting your small space
antennas up and effective.

Wayne
W5GIE/6

Unless there is something special about this coax, or if you are just going to use it for a television antenna, or something that you are only going to receive on - THROW IT AWAY!

once you exceed the minimum bend radius you open up the braid and the coax is never the same again.
THROW IT AWAY!

Coax has a shelf life - for example, Belden 9913 has a shelf life of about 10 years. Even though it was never exposed to sunlight and it was never taken out of the shed and was never exposed to the elements, after about 10 years, the coax starts to degrade and break down and then it is junk.

The kind of stuff you see at a swap meet, where the owner is still trying to get top dollar out of it.

Good Coax pays huge dividends in performance.

If all you are going to do is hook it up to a Ringo Ranger and put it on a tower, above the garage door of a fire station, and the county repeater is only 2 miles away, then yes - the quality of the coax doesn't matter much - other then the fact that it might show a false VSWR.

Like others has said, there is no way to predict what will happen when you go to use it unless you attach it to a Time Domain Reflectometer and sweep it! Something I doubt most hams would have - unless they work in the cellular telephone industry.

Unkinking Coax
 

On Sunday, October 19, 2014 10:29:29 AM UTC+11, Brian Reay wrote:
John S wrote:

On 10/18/2014 9:28 AM, Irv Finkleman VE6BP wrote:

I have a length of rg-58/u which was rolled up and when unrolled has

revealed some kinks. Has anyone any idea on how to smooth things out

again. It shows good on my analyzer, and I'm not worried about a bit

of migration which may have taken place. A bit of loss is of no real

concern to me. Someone suggested letting it rest in a tub of hot water

for a while, but that is the only suggestion so far.



Thanks in advance for any assistance,



Irv VE6BP



My first suggestion is to lay it in the midday sun an allow it to warm

for an hour or more. Then uncoil it and allow it to relax a bit longer.





I've used this technique on a real hot (for the UK) summer's day and found

it worked well, the only difference is I popped it in the airing cupboard

for 24 hrs first rather than leaving it in the sun. I then unrolled it on

my drive in mid afternoon, when the block paving was noticeably warm. The

cable was noticeably 'subtle' and the kinks came out easily. I rolled onto

a drum, with a tail free at the core, to aid checking. (So I could short

the end or terminate it etc. while applying a VNA to the free end.) I had

to 'snake' the cable to fit it on the drive.



Testing indicated the cable was within spec., at least to the limits of my

test equipment (said VNA and Bird power meter etc.)



I would not recommend either hot water or 'stretching'. Water ingress is

and obvious issue and stretching could change the dimensions.



You could, perhaps, use a hair dryer on a bad kink but I would be cautious.

I would probably write off that section. A heat gun would certainly be a

bit too hot, in my view. You don't want to damage the jacket or change the

dimensions.



The cable I recovered was double screened and worth saving, it had been

loose coiled by someone and picked up at a rally, with some matching

connectors for peanuts. Sadly, it wasn't 'fox proof' and one of the local

foxes decided to chew through it when I used it for long, experimental,

feeder run one winter. All part of life's rich tapestry.



73

Brian

G8OSN/W8OSN

www.g8osn.net

I know you were talking about coax, but I had a really good chuckle at the "noticeably warm" and "for the UK" comments. Thanks!

Unkinking Coax
 

Unkinking Coax
 

Channel Jumper wrote:
Unless there is something special about this coax, or if you are just
going to use it for a television antenna, or something that you are only
going to receive on - THROW IT AWAY!

I will be careful how I use it, keeping in mind it's history.

once you exceed the minimum bend radius you open up the braid and the
coax is never the same again.
THROW IT AWAY!

I don't have any reason to think that the minimum bend radius was exceeded.

Coax has a shelf life - for example, Belden 9913 has a shelf life of
about 10 years. Even though it was never exposed to sunlight and it was
never taken out of the shed and was never exposed to the elements, after
about 10 years, the coax starts to degrade and break down and then it is
junk.

I had the same piece of rg-8/u running up my tower and feeding assorted
antennas -- it was there from 1986 until 2007. I never really looked it
over for any signs of wear and tear, although once in a while I would
run my analyzer through it to test the assorted antennas. If I'd
noticed anything unusual I would have taken some action, but because it
continued to serve it's purpose, I continued to use it. I'm glad I
didn't know about shelf life and all the other stuff about coax or
I might have had ulcers by now.


The kind of stuff you see at a swap meet, where the owner is still
trying to get top dollar out of it.

I knew most of the vendors at the markets and while we always
wanted to get the best from our product, I don't think anyone would
take advantage of a fellow ham.


Good Coax pays huge dividends in performance.

'huge dividends'? Maybe a little gain or less attentuation, but
certainly not enough to consider it huge.
This was free -- just passed on by a friend.

If all you are going to do is hook it up to a Ringo Ranger and put it on
a tower, above the garage door of a fire station, and the county
repeater is only 2 miles away, then yes - the quality of the coax
doesn't matter much - other then the fact that it might show a false
VSWR.

Like others has said, there is no way to predict what will happen when
you go to use it unless you attach it to a Time Domain Reflectometer and
sweep it! Something I doubt most hams would have - unless they work in
the cellular telephone industry.

No one can predict, but there is intelligent guesswork. A TDR might
tell something, but putting the coax in a live situation usually works
well enough for ham radio purposes.

I run an amateur radio station, and if everything had to meet mil-spec I
wouldn't have had much. I did have my trusty MFJ-259B SWR analyzer,
which while it is not necessarily as a TDR, did serve me well, and as
far as the coax which led to this discussion goes, it did test OK when
fed into a dummy load over the HF bands.



The criterea which I lived by over 56 years of ham radio was 'did the
signals sound good, and could I make contacts?' -- and using old
hand-me-down wires and cables, and reusing various connectors I was
totally satisfied. It was ham radio on a budget -- I would hever throw
out something I might have been able to fix up and reuse. It kept me
very happy over the years and I'm not about to change now.

My two bits worth.

Irv VE6BP

Unkinking Coax
 

"Irv Finkleman VE6BP" wrote in message
...
Channel Jumper wrote:
Unless there is something special about this coax, or if you are just
going to use it for a television antenna, or something that you are only
going to receive on - THROW IT AWAY!

Like others has said, there is no way to predict what will happen when
you go to use it unless you attach it to a Time Domain Reflectometer and
sweep it! Something I doubt most hams would have - unless they work in
the cellular telephone industry.

No one can predict, but there is intelligent guesswork. A TDR might tell
something, but putting the coax in a live situation usually works well
enough for ham radio purposes.

I run an amateur radio station, and if everything had to meet mil-spec I
wouldn't have had much. I did have my trusty MFJ-259B SWR analyzer, which
while it is not necessarily as a TDR, did serve me well, and as far as the
coax which led to this discussion goes, it did test OK when
fed into a dummy load over the HF bands.



The criterea which I lived by over 56 years of ham radio was 'did the
signals sound good, and could I make contacts?' -- and using old
hand-me-down wires and cables, and reusing various connectors I was
totally satisfied. It was ham radio on a budget -- I would hever throw
out something I might have been able to fix up and reuse. It kept me
very happy over the years and I'm not about to change now.

My two bits worth.

Irv VE6BP


For ham use I agree, ues whatever you can get. If it is difficult to
install, then go with new stuff. I put up a tower with 4 beams stacked
above each other. Due to the difficulty in doing things over, I would not
use anything but new coax. I did mount some antennas on the side and used
some old coax as it is not difficult to replace it if it is not any good.

I have a 50 foot piece of some foam coax that is over 45 years old. It
spent about 20 to 25 years outside in use. Then just stored inside. I have
a spectrum analizer and tracking generator and swep the frequency from 1 to
1000 MHz. It seems to meet spec to about 30 MHz and then it starts to have
more loss than it should. As I get to around 400 it starts to fall off even
more.
I have not cut it open to see if the coax seems to have had water in it or
not.

A repeater I keep up started getting desense and other noise. Checked the
jumpers from cavity to cavity and found they were the problem so replaced
them. They were about 30 years old and had been in use inside a builden
that was not heated or cooled.





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