[Antennas] Stainless Steel Conduits

Sat Mar 14 10:04:31 EDT 2015

I have built J-Pole antennas for many years. I prefer the copper
mainly because it is easy to build especially for VHF/UHF.
 It also solders readily, making it easy to tune the feedline to
the stub.
I have a tri-band J-Pole (146/223/440) on top of my tower that I
built in the early 1980's and it has never required any maintenance.
It is built using 1 in, 3/4 & 1/2 in. copper water pipe. Couplings,
elbows, caps & Reducers are readily available at most hardware and
plumbing supplies.
73, Jim - w5ifp at gvtc.com
>> -----Original Message-----
>> From: Antennas [mailto:antennas-bounces at mailman.qth.net] On
>> Behalf Of KA4INM
>> Sent: Friday, March 13, 2015 9:06 PM
>> To: a
>> Subject: Re: [Antennas] Stainless Steel Conduits
>>>> On 03/13/2015 07:11 PM, Richard (Rick) Karlquist 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
>>>> > 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.
>>>> Copper, aluminum, brass and stainless steel are used to make
>> major brands of FM broadcast transmitting antennas.
>> Aluminum, and galvanized steel are used to make major brands of
>> TV broadcast transmitting antennas.
>> None have a reputation for being more or less efficient than the
>> other. The only known differences are the differences in
strength,
>> weight and the costs.
>>>> (there are known efficiency differences between antenna
>> designs)
>>>> I think the difference in the antenna efficiency between
copper
>> wire and stainless steel wire is being exaggerated in these web-
>> sites and discussions.
>>>> I am sure the difference between a sturdy "J pole" antenna
made
>> with copper (silver soldered) and stainless steel (brazed) of the
>> same size and design will be so similar in efficiency, cost and
>> longevity that they would be virtually indistinguishable.
>> Copper is much easier to machine and join than stainless steel.
>> --
>> Ron KA4INM - Youvan's corollary:
>> Every action results in unwanted side effects.
>> ___________________________________________________
>> ___________
>> Antennas mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/antennas
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Antennas at mailman.qth.net
>>>> This list hosted by: http://www.qsl.net
>> Please help support this email list:
http://www.qsl.net/donate.html