FWIW, I've got about 150 ft of 9913F in use at the moment. All was purchased
from Davis RF last fall. About 50 feet is being used for short flexible
links inside the shack and at the 2-radio switching system next to the
tower. I think the bends in the coax links are mostly within limits, but
some are pretty close. None of these links gets moved around. Impedance
measurements through these links are nearly identical to measurements made
before they were installed last December, and I've had no problems with
impedance changes since. I just installed a 70 foot run of 9913F up my new
AB-577/GRC 48' portable military mast. There's a standard rotor loop at the
top (2 feet or so) and the excess is in a large coil near the base of the
tower. I've not had any problems with this run either, although it is still
very new. If the center conductor migrates, it almost certainly would be at
the rotor loop. Time will tell (good thing it's a crank-up.)
I have another 80 feet of 9913F, recently purchased from HRO, that I had
intended to run up my U.S. Tower MA-770MDP to replace a run of RG-213. I've
tried LMR400UF for that run, but it's way too stiff. The 9913F has about the
same flexibility for that application as the RG-213, I think because of the
jacket material. But with all the talk about 9913F problems being discussed
on TT, I'm reconsidering. Any info about 9913F failures (other than from the
original poster, who made his clear) would be appreciated.
BTW, it's kind of hard to understand why 9913F would have problems with
center conductor migration and LMR400UF would not -- the construction inside
the jacket looks identical to me! Anybody know more about that?
73, Dick WC1M
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|