[Moon-net] LMR 400UF

[LANCE COLLISTER]

Hello Bob,

I had a similar problem with LMR-600 UltraFlex on 6m, and I understand there have 
been other similar situations.  Apparently, the coax is very soft, and it will deform 
if taped too tightly to a tower, or kinked or left in a permanent tight loop.  When 
it deforms from a true circular cross section or becomes pinched, the impedance 
changes and the loss goes up seriously.  I don't know what to suggest except be aware 
that it is very delicate and do your best to relieve any strain on it and prevent it 
from any sharp bends or kinking.  GL and VY 73, Lance


Bob Baker wrote:
> Dear Moon-net,
> 
> I am again in need of your wise, collective advice.
> 
> I just had a failure of a piece of LMR400 UF coax. It was only about 2 years
> old. It is clearly blown, SWR terrible, and you can see a small piece of the
> white dielectric sticking  through the black outer insulator.
> 
> I have a 2 yagi system, the other coax and antenna are working fine. Same
> coax, same age. swr perfect, looks almost new.
> 
> At the time of failure I was running 1500W jt65 144mhz. Measured at the
> antenna, the swr was about 1.3 to 1.4. The most power I could have had in
> the failed coax was 700W and it is rated at 1500W for 150MHZ. But my SWR was
> not perfect in the antenna with the failed coax.
> 
> Obviously I need to buy more coax. Has anyone had similar problems with LMR
> 400 UF? Was the cable defective or did I just push it a little too hard? Any
> recommendations? LMR 600UF?
> 
> Thanks in advance,
> 
> 73,
> 
> Bob
> KD3UY
> 
> 
> 
> _______________________________________________
> Moon-Net posting and subscription instructions are at http://www.nlsa.com/nets/moon-net-help.html
> 
> 


-- 
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: (406) 626-5728
URL: http://www.bigskyspaces.com/w7gj
2m DXCC #11/6m DXCC #815