[Antennas] Stainless Steel Conduits

[Kf6sza]

Just to clarify, guys, stainless steel conduit is available in many sizes and types of SS and is used heavily in the food industry.  We used to wrap SS conduit around SS wine tanks for the control wires and we even polished them out if the owner wanted them to look especially nice (and had the $$ to pay for it).

73,
Rich KF6SZA

Sent from my iPad

> On Mar 13, 2015, at 9:22 PM, charles berry via Antennas <antennas at mailman.qth.net> wrote:
> 
> You are probably right that I am looking at Galvanized Steel Conduit.  There was a time in my life that purchasing copper in any lengths was a non-issue.  My circumstances have changed and this conduit at 12½ ¢ a foot allows me to continue building my own antennas thus keeping my mind and hands busy.  Like the man said, 'Idle hands are the Devils workshop.  That being said,   
>   - If this steel conduit offers more resistance, do I shorten radiators to compensate?
>   - Can this conduit be soldered with small propane torches?
> I'm not trying to obtain World Peace, I just want to stay in the game building antennas.
> Thanks,Chuckn7chs
> 
> 
>     On Friday, March 13, 2015 4:11 PM, Richard (Rick) Karlquist <richard at karlquist.com> wrote:
> 
> 
>> On 3/12/2015 6:33 PM, charles berry via Antennas wrote:
>> Is Steel Conduit suitable for J-Poles and Active Booms?  The price of copper has made it extremely problematic in building antennas.  How is steel's velocity factor different than copper?
>> Thanks,Chuck BerryN7CHS
> 
> Much confusion posted here.  Let's clear this up.
> The web page cited is full of errors and misleading
> commentary.  Pure marketing, not science.
> Aluminum is the tried and true material for building
> antennas.  Its RF resistance is only 25% greater than
> copper, and in nearly all practical cases has
> negligible effect.  The RF resistance of materials
> scales as the square root of the DC resistance, which
> will come as news to the author of the web page.
> Copper is expensive, heavy, corrodes to lossy copper
> oxide, is structurally weak, and is difficult to
> machine unless alloyed with tellurium, which lowers
> the conductivity.  Any alloying metal that makes the
> copper into a brass or bronze lowers the conductivity
> to below that of aluminum.  I don't know that copper
> water pipe is pure copper rather than an alloy.
> In conclusion, there is virtually
> no reason to consider copper for the vast majority
> of antennas.  About the only thing copper really has going
> for it is that it can be soldered.
> 
> I don't know what the title of this posting:
> "Stainless Steel Conduits" is referring to; they don't exist.
> OTOH, (conventional) steel conduits are galvanized,
> so that for RF purposes they are essentially zinc.
> The DC conductivity of zinc is 27% of copper.
> Therefore, galvanized conduit will have
> about twice the RF resistance compared to copper.
> Thus if you really want to use galvanized conduit
> or pipe for antennas, the additional RF resistance
> is probably not a show stopper in most cases.
> 
> Now if you did try to use a stainless steel tube for
> RF purposes, that is a problem.  Not only is the DC
> resistance much higher than aluminum, but some SS is
> magnetic, which makes it even lossier at RF.
> I had a client once who wanted to use some nickel
> tubes to make a transmission line.  (I know, dumb
> idea, but the client (who has money) is always right.)
> I measured the RF resistance of the nickel and found
> that it was much higher than would be predicted by
> DC resistance.  This indicated that the magnetic
> permeability was a big factor.  Stainless steel has
> both nickel and chromium in it.
> 
> You do see stainless steel CB whips (102 inch) which
> have to be made of SS for mechanical reasons.  You
> just have to live with the extra RF loss.  Mobile
> installations have many other sources of loss, so
> in the overall scheme of things, the SS whip is not
> so bad.  But it is a special case.  I love my 4 inch
> Hi-Q screwdriver with a 102 inch whip on top.
> 
> Finally, velocity factor is a property of dielectrics
> not conductors.  A stainless steel CB whip resonates
> at 27 MHz, just like it would if it were made of copper.
> 
> Rick N6RK
> 
> 
> 
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