I'll bet you don't drink Global Warming Kool-Aid either :-)
Gary J
N5BAA
-----Original Message-----
From: Patrick Greenlee
Sent: Friday, December 19, 2014 2:56 PM
To: Gary Schafer ; towertalk@contesting.com
Subject: Re: [TowerTalk] A couple of 18HT questions
Gary, You misunderstand my meaning. Another try... Hy-Gain has sold
Hy-Towers since the 50's and I know of no failures due to corrosion of
those tubes. Has there been one? Anyway, those telling us of the the
dangers caused by "chemistry" are like the aerodynamics types claiming
the bumble bee couldn't fly. The bee flies and the tower doesn't fall
down due to corrosion of the aluminum due to concrete contact. Ground
truth trumps speculation however informed.
Oh, by the way, I did take that physics class and a bunch of others and
was a physicist before finding true religion (computers) and getting a
BSCS and MS softwarre engineering.
I'm the guy who pokes pins in others balloons, recommending
(allegorically) that rather than pontificate and guestimate at the
number of angels dancing on the head of a pin, get a lens and count the
little buggers! Fact trumps theory. I don't deny that the concrete
corrodes the aluminum but given the facts related to the number of
towers failing, apparently the corrosion isn't significant. There are
towers out there with aluminum legs in concrete for over 60 years. If
corrosion was a significant issue you'd think there would be eHam
postings mentioning that.
Patrick NJ5G
On 12/17/2014 9:13 PM, Gary Schafer wrote:
You should have taken the physics course too. :>) The old "bumble bee
shouldn't be able to fly" is an old wives tale that has been around for
ages.
73
Gary K4FMX
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
Patrick Greenlee
Sent: Wednesday, December 17, 2014 8:00 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] A couple of 18HT questions
Yeah, I had the requisite year of freshman chemistry too but lets get
real. Hy-Gain has been making these antennas for how long? They have
been putting aluminum into concrete for how long? Anyone ever here of a
failure due to corrosion of the aluminum? I don't have a dog in this
fight as I replaced the thick walled aluminum tubes with solid steel
bars as in mounting on the roof of my barn I wanted to weld the three
"posts" to some of my custom base components (steel) and I'm not good at
welding steel to aluminum. I still have the aluminum tubes awaiting a
use to present itself.
Somehow I am reminded of the old story of the bumble bee and the
aerodynamicists. :-) ;-) :-D
Patrick NJ5G
On 12/17/2014 3:36 PM, L L bahr wrote:
I have had my 18HT up for 30 years with aluminum tubes in the
concrete. I see no signs of deterioration. That's good enough for me.
Lee, w0vt
> You do not want concrete in contact with aluminum! It will eat up
the
aluminum. Even aluminum windows come with a warning to not let the
brick
mortar come in contact with the aluminum frame when installing.
After the concrete is set and dried it may be ok then, not sure.
73
Yes indeed.. Aluminum is readily attacked by most acids and bases: the
surface oxide helps a lot, and, of course, a chemical conversion
coating
(anodize, alodine) would too. BUT, a scratch in the coating provides a
nice surface to be attacked.
ALuminum is attacked by most basic hydroxides (e.g. sodium hydroxide,
lye, is used to etch aluminum panels).. It is a way to make hydrogen
gas, in fact.
Mortar is a mixture of quicklime (CaO) and sand, for the most part,
and
when you add water to it (slaking the lime) it forms Calcium Hydroxide
(Ca (OH)2).
Concrete has similar chemistry.
So, yes.. keep your aluminum out of the concrete footing.
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