I realized today doing some cursory checks on copper vs. aluminum
prices that you can nearly purchase a small TIG welder with the savings
of using aluminum instead of copper in a big magloop (think 10' square,
2" tubing low bander). I think it even holds true if you use larger
diameter aluminum to make up for the lower conductivity of aluminum vs.
copper.

Just a thought if you've always wanted to use aluminum in a large
magloop but went to copper because you couldn't figure out how to get
low-resistance joints in aluminum!

73,
Dan

wrote
I realized today doing some cursory checks on copper vs. aluminum
prices that you can nearly purchase a small TIG welder with the
savings
of using aluminum instead of copper in a big magloop (think 10'
square,
2" tubing low bander). I think it even holds true if you use larger
diameter aluminum to make up for the lower conductivity of aluminum
vs.
copper.

Just a thought if you've always wanted to use aluminum in a large
magloop but went to copper because you couldn't figure out how to
get
low-resistance joints in aluminum!
====================================
Dan,

The difference between loss resistance of copper and aluminium at HF
is unnoticeable. It is only about half of the difference between the
conductivities of the two metals which is quite small anyway. It is
something to do with skin effect.

I once had a 12-feet diameter, 1.7" conductor diameter, aluminium
magloop. It had belonged to a deceased blind amateur for several
years. I used it successfully on the 160 and 80 meter bands.

It was in two semi-circular halves. The halves had been bent into
semi-circles by machine. Aluminium is quite a ductile material. The
halves had swaged ends which fitted inside each other. Easily
dismantled for transportation. I never noticed any poor electrical
connections.

The whole structure was lightweight. Much less than the weight had it
been copper. And although it was several years old it had stood up to
the English weather very well. It still looked almost new.

It was supported at the top by a vertical aluminium mast which formed
a T-section in conjunction with the motor-driven tuning capacitor
assembly. It was rotateable by hand through more than 90 degrees
between 3 equi-spaced guy ropes. There is no interaction between a
diametrical vertical mast and a circular loop.

There was a small 1/5th diameter, self-supporting coupling loop
located at the bottom of the main loop and insulated from it. The
coupling loop was fed via 50 feet of 75-ohm coax. No RF on the
outside of the feedline.

I never knew the sort of machine operation used to bend the
semi-circular halves from straight thin-wall aluminium tubes. It had
been done very accurately. I doubt it was extruded already bent.

It was eventually swapped to a 3rd amateur for a bottle of port wine
and may still be in use somewhere.
----
Reg, G4FGQ.