wrote:
If you are talking about home brew stuff, the general solution is to
clean, apply anti-oxide grease, and connect under compression, i.e.
something with a tightening screw.

I'm putting my rotatable 20m dipole back up and am,
once again, needing to connect ladder-line to
aluminum tubing out in the weather. I guess I'll try
brass hardware this time.
--
73, Cecil http://www.w5dxp.com

Brass?

Buck
www.N4PGW.org

On Fri, 07 Nov 2008 14:36:58 -0600, Cecil Moore
wrote:

I'm no metallurgist so forgive my ignorance. Most of
us have had the problem of interfacing copper to
aluminum. Is there some sort of alloy terminal block
that will accomplish that feat? Seems simple enough
to create an alloy that gradually transitions from
copper to aluminum but what do I know?

--
73 for now
Buck, N4PGW

www.lumpuckeroo.com

"Small - broadband - efficient: pick any two."

Cecil Moore wrote:
wrote:
If you are talking about home brew stuff, the general solution is to
clean, apply anti-oxide grease, and connect under compression, i.e.
something with a tightening screw.

I'm putting my rotatable 20m dipole back up and am,
once again, needing to connect ladder-line to
aluminum tubing out in the weather. I guess I'll try
brass hardware this time.

If there isn't already, stuff a short hunk of something solid like a
fiberglass rod or wood dowel in the end where you make the connection,
put terminals on the wires, use stainless screws with star lock washers
under the screw head and between the terminal and tubing and the terminal
and nut, anti-oxide grease, overwrap with sealing tape then with regular
tape.

That's how I connected to the vertical in the middle of my lawn where
the sprinklers hit it about a decade ago and there have been no
problems.

FWIW, I tried brass (because someone gave me a bunch) for this sort of
thing and switched to stainless.

--
Jim Pennino

Remove .spam.sux to reply.

Red, yellow, and naval brass as well as aluminum bronze alloys are
marginally anodic with respect to copper so these alloys would provide
minimal corrosion protection. I know it might not be obvious, but steel
would make a better intermediate metal.

This will make sense if the actual voltages are included in the galvanic
series. These voltages are in sea water and with respect to a standard
calomel electrode.

Zinc -0.98
to -1.03
volts
Aluminum -0.70 to -0.90 "
Cast Iron -0.60 to -0.72
"
Steel -0.60
to -0.70
"
Red Brass, Yellow Brass, Naval Bross,
Aluminum Bronze -0.30 to -0.40 "
Copper -0.28 to -0.36
"


73, Barry WA4VZQ

Always use Antenna Grease or equivalent on Aluminum contact points to keep
the oxidation and moisture out. Steel is subject to rusting, so Stainless
Steel or Galvanized Steel is best for antenna hardware to clamp to the
Aluminum, and use tinned Brass or Copper loop-eye terminals soldered to the
Copper wire and bolted with Stainless Steel or Galvanized hardware.
Stainless should have a little Petroleum Jelly, NoAlox or Antenna Grease to
keep threads from seizing. I have used Stainless Steel hose clamps and they
work fine for quite a while.

Aluminum house wiring has been banned a lot of places and is a bad idea all
around.
The problem is that the Aluminum is weaker. As it is flexed and heated at
the connections, it will migrate out and the connection will get loose and
you will have a cascade of oxidation and increased resistance. The
recommended answer for that failure (If your house didn't burn) was to use a
copper wire pigtail out to a wire-nut connection to the existing Aluminum
wire with no-alox in the mix. Obviously, there is a loss of integrity and
"how to jam the wire nuts into the box" issues. If you have Aluminum house
wiring, you should keep an eye on line drops all through the house and run
new wiring for any big draw appliance addition.

Bart Bailey wrote:
What about stainless hose clamps for more surface contact,
and of course a liberal application of anti-oxide paste,
maybe even some of that self vulcanizing tape on top of it all to try
and obviate WX effects?

Been there, done that. Nothing seems to completely
solve the problem forever.
--
73, Cecil http://www.w5dxp.com

"NoSPAM" wrote in message
...
----- Original Message -----
From: "Sal M. Onella"
Newsgroups: rec.radio.amateur.antenna
Sent: Friday, November 07, 2008 11:20 PM
Subject: Aluminum to Copper interface


snip

2. I see a lot of brass and darn little corrosion. Would a transition
piece of brass be acceptable?

"Sal"

Red, yellow, and naval brass as well as aluminum bronze alloys are
marginally anodic with respect to copper so these alloys would provide
minimal corrosion protection. I know it might not be obvious, but steel
would make a better intermediate metal.

This will make sense if the actual voltages are included in the galvanic
series. These voltages are in sea water and with respect to a standard
calomel electrode.

Zinc -0.98
to -1.03
volts
Aluminum -0.70 to -0.90 "
Cast Iron -0.60 to -0.72
"
Steel -0.60
to -0.70
"
Red Brass, Yellow Brass, Naval Bross,
Aluminum Bronze -0.30 to -0.40 "
Copper -0.28 to -0.36
"

I saw those numbers decades ago -- in chem class, I guess. I cited brass
only because it seems to resist corrosion well, not because I actually know
what I'm talking about. g

73,
"Sal"
(actually KD6VKW)

"Sal M. Onella" wrote in message
...
I saw those numbers decades ago -- in chem class, I guess. I cited brass
only because it seems to resist corrosion well, not because I actually
know
what I'm talking about. g

Hi Sal,

As an instrumentation designer who worked mainly in the chemical industry,
corrosion abatement and material selection were daily facts of life. On
more than one occasion, the company metallurgists saved my rear end. For
example, stainless steel can be both cathodic and anodic with respect to
itself. While most folks consider stainless a panacea for corrosion
problems, it is not. In fact stainless alloys have little resistance to
salt water. There are many poor owners of stainless auto exhaust systems
that learn this the hard way when streets are salted in the winter to melt
ice. Copper, brass, and bronze alloys are used in marine environments
because of their anti-biofouling properties (barnacles, coral, mussels,
etc.).

I try to make my posts educational when I can. Thanks for telling me that
you had seen these numbers before. I hope they made a little sense this
time. I think if we all were back in school, we might pay more attention
this time. I know I would!

73, Barry WA4VZQ

The answer is a tinned crimp-sleeve or a tinned mechanical sleeve
Here's one http://www.rshughes.com/products/054007_13319.html
Hope this helps

"Cecil Moore" wrote in message
...
I'm no metallurgist so forgive my ignorance. Most of
us have had the problem of interfacing copper to
aluminum. Is there some sort of alloy terminal block
that will accomplish that feat? Seems simple enough
to create an alloy that gradually transitions from
copper to aluminum but what do I know?
--
73, Cecil http://www.w5dxp.com

Who woulda thunk it - Look at this alum-to-copper twister wire connector
http://www.idealindustries.com/produ...ster_al-cu.jsp
Google helped to find it
Hope this helps
Hal - W4PMJ

"Cecil Moore" wrote in message
...
I'm no metallurgist so forgive my ignorance. Most of
us have had the problem of interfacing copper to
aluminum. Is there some sort of alloy terminal block
that will accomplish that feat? Seems simple enough
to create an alloy that gradually transitions from
copper to aluminum but what do I know?
--
73, Cecil http://www.w5dxp.com

"NoSPAM" wrote in message
...

snip

I think if we all were back in school, we might pay more attention
this time. I know I would!

Yup. A smarter man than I said, "We'll only need about five percent of what
we learned in college; too bad nobody knows which five precent."