[AMRadio] Tubing

Jim Wilhite w5jo at brightok.net
Tue Jul 10 08:50:44 EDT 2007

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.


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" <w5saw at pathwayz.com>
To: "AM Radio Mail List" <amradio at 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
> w5saw at pathwayz.com
> "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" <rickbras at airmail.net>
>> To: "'Discussion of AM Radio in the Amateur Service'"
>> <amradio at 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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