Coax facts

This has been up for 6 days and no discussion on 18 feet, shortest distance, or something shorter, or something longer?

 

I've always cut it long enough to get to the radio. I can't find any info that says it has to be a certain length for any freq.


Sent from my iPhone using that Tapatalk thingamabobber.

 

I've got 25 feet bran new LMR 240 uf. Just need to figure how much to use. Could use the shortest and try that. then go the vf route and try that. It seems that most agree on 50 ohm cable, shortest is best.

 

It will all depend on how good your rf ground is. Or how far you are willing to go to make it good.

 

Assuming your antenna is tuned and matched properly, the correct length is whatever is needed to get from the antenna to the radio, plus enough to be able to remove the radio (or antenna) if needed.

If you are trying to use the coax as a matching network, then your guess is as good as mine, because each installation is different.

 

Coax length only matters if you want to use an SWR meter at the radio end of the coax (which you shouldn't do anyway, because it is best to connect an SWR meter at the antenna's feedpoint).

Otherwise, it is exactly as MsJamie said: use the shortest length of coax that you can.

Remember, longer runs = more loss.

 

the 18 feet myth probably came about from that being the average number of feet to run an antenna in a big truck. i have a nissan hardbody truck, and from the glovebox where my 2510 is mounted, the coax is run to the left, under the shifter boot between the seats, out the left rear window down the bed rail to the antenna mounted on the left rear quarter panel. yup. 18 feet. go figure lol

 

The 18 ft myth probably came from the antenna manufactures who used to, and may still, recommend that length and sell their antennas with that length of coax.