Hello: I am just starting into antenna building and have a question...Using aluminum rods, how do I connect wires (coax) to to them...I understand that you cannot solder to aluminum...Advice appreciated!
Steve KA1OWC
Hello: I am just starting into antenna building and have a question...Using aluminum rods, how do I connect wires (coax) to to them...I understand that you cannot solder to aluminum...Advice appreciated!
Steve KA1OWC
Best thing I can suggest is to use closed ring crimp connectors on the inner and outer conductors of the coax, and then use the appropriate size screws (bolts) and nuts to attach them to the aluminum. Depending on what material the crimps are made of, you may experience some electrolysis or galvanic action, best minimized by using a paste that is made to go on all the connection points. It is readily available on the web or in many hardware stores. Next time you are in a place that sells TV antennas, or a ham store, look at how they are done. Most use rivets, which is also doable, but for the DIYer, I think screws will provide a better long term connection.
But then, I could be full of shit, too.
A clear conscience is usually a sign of a bad memory
RIP ALBI-W3MIV RIP RUSS-W5RB RIP BOB-VK3ZL
La Rata is not full of shit (for once), that is the best way. Another method I've used is stainless steel worm drive hose clamps. Just stick the conductor under the clamp and tighten it down.
If you can find them in the correct size, you can also use these things. Put a ring terminal on the conductors, then attach that to the screw (stainless steel is best) that tightens the clamp.
The advantage to the last two methods is that they allow for feed point adjustment when it's needed.
Last edited by NQ6U; 08-10-2017 at 12:17 PM. Reason: added "feed point"
All the world’s a stage, but obviously the play is unrehearsed and everybody is ad-libbing his lines. Maybe that’s why it’s hard to tell if we’re living in a tragedy or a farce.
Tin your copper leads with solder first. I would get an SO-239 connector and mount it in a weather proof box and connect your leads to the antenna from that. If the individual leads are longer than 1 inch then insulate each one and slide ferrite beads over them. Hell, I'd do the same even if the were an inch.
All good suggestions.
As Eddie stated: Make sure to coat your element rods with NoAlox or similar paste where the clamps will attach (if you use them).
"Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."
There is alumium solder and aluminium flux. I've used the solder, it works but doesn't flow well so I force it into shape using "wiped" joints just as you'd use in plumbing to join copper and lead pipes.
As for the flux, which claims to solder any metal to aluminium, well I don't think it works reliably well.
With Al tube, if you can plug the ends with solid aluminium rod and tap a thread right through for a long screw, I think it gives you a good contact area out of the weather, leaving less sealing required
Looking at the reactivity table for metals (goes M A Z I T L as in magnesium, aluminium, zinc, iron, tin, lead) it is much of a guide to the screw material? One thing though, stainless steel has a poor conductivity.
Now that I wasn't aware of.Originally Posted by HUGH
Like that post was...
Moving on, my posts are not helpful
The stainless steel conductivity issue confuses me. Is there more information on this.
Obviously there are at least 2 common grades of stainless steel and I haven't checked precisely what the difference is but when I worked at a motor drive manufacturer, we carried out some tests using stainless steel screws for the terminals both inside and out (user terminals) of DC drives.
The screws became very hot at full current (the 200A region) compared to the normal plated mild steel and, as the inner ones carried the coils which were the current measurement transformers, the coils were sacrificed to the great smoke god.
Consider the domestic utensils made from stainless steel which includes pans, mugs, kettles and so on. Our saucepans are copper based otherwise they would take an age to heat up. Drinking mugs and kettles don't become as hot on the outside as those made from, say, aluminium.
One of our local radio club members uses stainless steel electric fence wire for an antenna and the total resistance is measured in tens of ohms. Another, experimenting at LF and VLF, reports that, with about 3kW RF out, the stainless steel screws connecting various bits together were literally a dull red heat, damaging some of the other bits of hardware. I suggested using smaller screws with a copper sleeve.
This seems a comprehensive guide:
http://eddy-current.com/conductivity...y-resistivity/
Last edited by HUGH; 08-09-2017 at 11:59 AM.
Thank you. This is good information.
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