One suggestion to what Steve posted here. Fill the tubing
with sand to prevent unwanted crimps in the tubing as you
form it. That will maintain the concentric shape.
Jim/W5JO
Don't forget to remove the sand before installation and blow
out the tubing with compressed air. Use a source of air
with a dryer on it.
----- Original Message -----
From: "Stevan A. White" <[EMAIL PROTECTED]>
To: "AM Radio Mail List" <amradio@mailman.qth.net>
Sent: Monday, July 09, 2007 10:04 PM
Subject: [AMRadio] Tubing
Good guess, use copper tubing from your favorite home
center store! What you see in the transmitter is more
likely than not silver plated copper tubing.
When I was the chief engineer at an AM station with a 5
tower AM directional array several years ago and we
rebuilt the phasing and tuning circuits used plain old
copper tubing from Lowe's. I mashed the ends flat with
lineman's pliers, nipped off the sharp corners using the
cutter part of the same pliers then dunked it in a solder
pot to tin the ends well. Silver solder like plumbers use
is the best but regular resin core solder will work too,
you just have to clean the sticky gunk off after it cools.
Clean the ends well with emory cloth before you shape it
and use a punch to cut your holes before you tin it or a
drill afterwards if you don't have a punch. Whatever you
do, don't use acid core solder! If you don't own a solder
pot, try an old (small) saucepan or maybe a food can on a
camp stove. Be sure to use something that will take the
heat because silver solder has a higher melting point than
resin core solder.
You've already mentioned that you need 1/4" diameter
tubing so you should be OK using the cheap copper swamp
cooler tubing from Wally World. We used 1/2" for our 10
kW system so you ought to be good for several thousand
watts.
Stevan A. White, W5SAW
SW Commercial Electronics
928 South Crockett Street
Amarillo, Texas 79102
Phone 806-681-7228
[EMAIL PROTECTED]
"Our five senses are incomplete without the sixth -- a
sense of humor." -- Source Unknown
Bill Smith wrote:
Automobile air conditioning line? Or perhaps tubing from
a refrigerator?
Bill
----- Original Message -----
From: "Rick Brashear" <[EMAIL PROTECTED]>
To: "'Discussion of AM Radio in the Amateur Service'"
<amradio@mailman.qth.net>
Sent: Monday, July 09, 2007 6:51 PM
Subject: [AMRadio] Tubing
I need to make a couple of RF connections using 1/4" O.D.
tubing. The stuff
that is already in the transmitter appears to be soft
steel of some kind.
It's not aluminum and could possibly be coated copper.
Any ideas of what
this is? I checked McMaster-Carr and they have some
annealed steel aircraft
tubing that appears to be similar, but I'm not sure. I
only need a couple
of feet, so I hate to buy $30.00 to get it.
Thanks for any help or advice...
Rick/K5IAR
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