Coax Question

What kind of coax is it?

 

you can try copper electronics. they have been around forever.

http://www.copper.com/cart/index.php?cPath=39_57

 

First let me say I do not have experience in base stations. For a single antenna setup you need to use any of several available 50 ohm resistance coax cables. In a mobile cb radio setup like a truck, the type of 50 ohm cable that you use is not a big deal because of the short lengths that are used ie. 18 feet of cable or [preferrably] less. A base station can be very different because of the much longer lengths of cable runs.
.
.RG 58 has 0.34% lose of signal per foot with an outside diameter of 0.195 inches that makes it easy to handle
.RG 8X has 0.22% lose of signal per foot with an outside diameter of 0.242 inches
.LMR 240 has a 0.16% lose of signal per foot with an outside diameter of 0.240 inches it has a Solid center conductor which is hard to route
.LMR 240 Ultra has a 0.16% lose of signal per foot with an ouside diameter of 0.240 inches and has a stranded center conductor
.LMR 400 has a 0.14% lose of signal per foot with an outside diameter of 0.405 inches and has a solid center conductor
.LMR 400 Ultraflex has a 0.14% lose of signal per foot with an outside diameter of 0.405 inches and has a stranded center conductor
.There are other types of 50 ohm resistance cable. These are just the more common types.
.
.Cables that have lower lose of signal have higher costs. Another company to check out is www.Universal-Radio.com/catalog/cable.html

 

Umm aren't those percent losses suppose to be for every 100 foot?

 

It's normally expressed in dB/100'. Percent/foot is valid, but my quick calcs show those numbers to be a bit on the low side.

 

Ok so thats why it looked weird to me.. I did a lot of comparing a few months ago on the hunt for some for my base. Ended up going with lmr400. A trick a ham told me about was you can actually run say like 100 ohm on long runs as long as you put about 8 foot of 50 ohm at each end of the 100 ohm coax

 

Sort of, but not quite. If you want to use non-50Ω coax on a 50Ω system, you can use a length that's a multiple of an electrical half wavelength. (That's electrical length, not physical length.)

If that 100Ω coax has a velocity factor of 0.66 (typical for coax), a half electrical wavelength piece of coax for channel 19 is 11.36 feet. So, if you needed to go 50', you'd need to use a 56.81' piece of 100Ω coax. (If you only had 50' of it, you'd need to cut it at 45.45' and make up the extra 5' with a 50Ω jumper.)

It works. A club I was in used 75Ω cable TV hardline for its repeater. Once trimmed to proper length, it worked beautifully. Not bad for free!