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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

Source for stainless steel tubing (small diameter)



 
 
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  #1  
Old December 31st 04, 01:24 AM
[email protected]
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Default Source for stainless steel tubing (small diameter)

I am wanting to get into amateur radio antenna building most plans for
a j pole antenna I have seen use 1/2 inch coper tubing. I was wondering
if I could use stainless steel to make it rust proof. Any ideas where
one could cheaply get small diameter stainless stell tubing?
Any of you out there work with amateure radio antennas?

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  #2  
Old December 31st 04, 02:09 AM
RoyJ
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Stainless is readily available, it's non rusting, and is also much
siffer than copper so you can use thinner wall. Downside is that it ahs
much higher resitance than copper, tends to mess up both the gain from
the antenna as well as the exact dimensions.

wrote:

I am wanting to get into amateur radio antenna building most plans for
a j pole antenna I have seen use 1/2 inch coper tubing. I was wondering
if I could use stainless steel to make it rust proof. Any ideas where
one could cheaply get small diameter stainless stell tubing?
Any of you out there work with amateure radio antennas?

  #3  
Old December 31st 04, 02:44 AM
Jerry Martes
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wrote in message
oups.com...
I am wanting to get into amateur radio antenna building most plans for
a j pole antenna I have seen use 1/2 inch coper tubing. I was wondering
if I could use stainless steel to make it rust proof. Any ideas where
one could cheaply get small diameter stainless stell tubing?
Any of you out there work with amateure radio antennas?


Stainless would work OK for a j pole. You probably couldnt notice the
difference by ear when operating at frequencies below 400 MHz.
It has always been my experience with HAM antennas that I wouldnt invest
much time in any design that wasnt close to *the best* performance. Copper
is really a good performer for antennas. Aluminum, is often a necessary
compromise. Stainless is great for automotive mounted antennas.
I suggest you post your question on Rec RadioAmatuer Antenna. There are
some *very* well informed guys there.

Jerry


  #4  
Old December 31st 04, 02:45 AM
Glenn Ashmore
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I tried building a stainless QFH antenna to pick up weather satellites but
the resistance is so much higher than copper that it turned out way off the
target 137 Mhz. I ended up with 1/4" hard wall ACR copper and nickle plated
it. If you want to try stainless McMaster has 50' rolls of 304 stainless
tube that bends pretty well.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

wrote in message
oups.com...
I am wanting to get into amateur radio antenna building most plans for
a j pole antenna I have seen use 1/2 inch coper tubing. I was wondering
if I could use stainless steel to make it rust proof. Any ideas where
one could cheaply get small diameter stainless stell tubing?
Any of you out there work with amateure radio antennas?



  #5  
Old December 31st 04, 03:16 AM
[email protected]
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Default


Jerry Martes wrote:
wrote in message
oups.com...
I am wanting to get into amateur radio antenna building most plans

for
a j pole antenna I have seen use 1/2 inch coper tubing. I was

wondering
if I could use stainless steel to make it rust proof. Any ideas

where
one could cheaply get small diameter stainless stell tubing?
Any of you out there work with amateure radio antennas?


Stainless would work OK for a j pole. You probably couldnt notice

the
difference by ear when operating at frequencies below 400 MHz.
It has always been my experience with HAM antennas that I wouldnt

invest
much time in any design that wasnt close to *the best* performance.

Copper
is really a good performer for antennas. Aluminum, is often a

necessary
compromise. Stainless is great for automotive mounted antennas.
I suggest you post your question on Rec RadioAmatuer Antenna.

There are
some *very* well informed guys there.

Jerry


Would making the stainless steel j pole elements slightly larger in
diamter compared with a copper j pole plan over come the higher
resistance?

I thou8ght about aluminum but dont have the capability to weld it. I
thought with stainless I could fishmouth the tubes and weld them
together. I am just thinking at this point.

What about using EMT tubing? Is this rust resistant? It is cheap and
light and easy to work with.

I love fooling around in my garage with stuff. I was wondering if it
was possible maybe to make a few bucks doing this as a hobby. I have a
seocond child due any day and money will soon start to be hard to come
by!

Think this is a possibility? ANything else out there a guy could do in
his garage in his spare time to make a buck?

  #6  
Old December 31st 04, 03:39 AM
[email protected]
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Why not just use copper pipe? It won't rust. You could weld them up if
you don't want to use pipe fittings.

  #8  
Old December 31st 04, 04:36 AM
axolotl
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Glenn Ashmore wrote:

I tried building a stainless QFH antenna to pick up weather satellites but
the resistance is so much higher than copper that it turned out way off the
target 137 Mhz.


A change in resistance will not change the resonant frequency.
Resistance will affect the Q and bandwidth.

Kevin Gallimore



  #9  
Old January 1st 05, 12:13 AM
[email protected]
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Copper is kind of ugly and tarnishes which I would think would increase
the resistance over time.

  #10  
Old January 1st 05, 03:24 AM
Jerry Martes
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This is your project and you can use any material you want. But you have
no reason to *not* use copper because of the degradation of the electrical
characteristics when it gets tarnished. The RF resistance of the
tarnished looking copper wont be degraded.
I havent seen the post where you indicated the frequency this j-pole will
operate.

If your pervious post about making money by building j-pole antennas for
HAM use implies that you think there is a profit to be had by building
j-poles, I'd advise you to get the orders first.

Jerry


wrote in message
oups.com...
Copper is kind of ugly and tarnishes which I would think would increase
the resistance over time.



 




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