LMR 400 With Short Jumper

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rangers38

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I currently have a BCD996XT scanner hooked up to a Diamond D130JN antenna. I have purchased a 100 ft length of Times Microwave LMR 400 with N connectors. I have a lightning arrestor connected to the end of the 100 ft length. From the lightning arrestor I have a 15 ft length of LMR240 going to the scanner. My question is am I losing any reception in the short length of LMR240 or should I have the small jumper from the arrestor to the scanner in LMR400?
 

kb2vxa

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Neither actually, the arrestor should be outdoors and well grounded for safety. Conducting lightning into the structure is dangerous and foolhardy.
 

mpddigital

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SW GA - 30 years South of Atlanta
LMR400 to a LMR240 Jumper

It is common practice to use a LMR-240 or LMR-195 jumper at the end of a longer LMR-400 run as needed. Although LMR400 will turn 90 degrees in 1 inch without attenuation it is stiff and doesn't like repeated flexing. You should not notice the loss.

Your lightning arrester should be the right one for the frequencies you are working and Very Well grounded. Don't scrimp on the ground or you will see no benefit when needed.
 

dksac2

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Idaho
I use the LMR 240 with the stranded center connector for my jumper from the LMR 400 that comes through my window connection point.
Your lightning arrestor should be connected to the ground wire that goes to the power panel with #6 wire and as short of a run as possible, then you will have a correct ground.

The LMR 240 with the stranded center connector will loose less signal than any other thinner cable I know of and is plenty flexable enough.If VHF/UHF frequencies are a primary frequency, use "N" connectors where ever you can and keep your run as short as possible even using LMR 400.

John
 

mainetrunk

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York county Me.
I have a similar setup as rangers38. Instead of the 396xt-my LMR 400 goes to my bct15x. It goes 40 feet to my ferret. When my cable-parts were put together by Southern Me. Communications, I noticed the JUMPER cable ( 20 inches ) was very thin. A beldden s219. I asked if there would be loss-they said it shouldnt. Well, being 140 feet above sea level, I started scanning the Goffstown EDACS system..( when it was used by pd ). Well, I looked at my signal strength, and it was full tilt. That is how I constantly check the ferrets reception. I know pd moved to p25, but if the signal is there, use it. Their DPW uses it now. The only system I ever heard of that the DPW is on it-alone..So, now I use LMR 400 for everything EXCEPT the vehicle. Thats a company secret. I will say my vehicle antennas are THE BEST you can buy. In my area that is. All band is the way to go-with LMR 400. Ron
 
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