[amsat-bb] LMR-400 direct to antenna or no?
tosca005 at umn.edu
Sun Apr 3 01:48:26 UTC 2016
I beg to differ. As long as there is a reasonably-sized, loose loop around
the mast, LMR400 will last for years to decades, not days. Mine did, for 20
years, in Minnesota weather (temps ranging from -30F to +100F). Planning to
do it again when the tower goes up here in Texas.
73 de W0JT/5
On Thu, Mar 31, 2016 at 10:33 PM, Glen Zook via AMSAT-BB <amsat-bb at amsat.org
> Use LMR-400 around the rotor if you want to have to replace the cable
> every few days!
> LMR-400 has a solid center conductor and it will definitely break after
> being "flexed" for not that many times!
> Frankly, for short runs like around rotors and to most antennas, plain old
> RG213/U works fine and the loss is very low. Run the LMR-400 up to just
> below the rotor and then install the RG213/U the rest of the way.
> I use either 1/2-inch Heliax or 7/8ths-inch Heliax for almost all my
> antenna runs from 160-meters through 70 cm. Where a rotor is involved, the
> Heliax goes up the tower to just below the rotor and then RG213/U the rest
> of the way. Most of the antennas have been "up" for a pretty long time
> (decades) and they are working just as well today as they did when first
> erected. Glen, K9STHAMSAT 239 / LM 463Website: http://k9sth.net
> From: Scott <scott23192 at gmail.com>
> To: amsat-bb at amsat.org
> Sent: Thursday, March 31, 2016 8:35 PM
> Subject: [amsat-bb] LMR-400 direct to antenna or no?
> I hope to put up my first rotating antenna soon and just received a nice
> length of LMR-400 to use. (regular, not "super-flex")
> Having never seen LMR-400 before, I did not know how flexible it would
> be. I would call it "medium"... not stiff as a pipe but not floppy, either.
> My question is whether anyone using LMR-400 can recommend whether I should
> attach it directly to my antenna (with slack loops, of course)?
> Or, should I get a few meters of something more flexible to attach to an
> antenna that needs to be free to rotate 360 degrees?
> If a jumper is recommended, I would appreciate suggestions on what cable
> would work best for the task. The frequency for this project is 70cm.
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