[amsat-bb] LMR-400 direct to antenna or no?

Glen Zook gzook at yahoo.com
Fri Apr 1 03:33:45 UTC 2016

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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