Length of cable

[Dfgarland]

What is the longest possible run of cable be between the scanner and antenna? Also wondering what is the best cable to get and if there are different longest lengths for each kind. I have radio shack discone antenna and Uniden bct15x. Thanks for any help.

 

[jackj]

Dfgarland, you can run as much coax as you want. Your scanner might or might not work, depending on how long the coax is as well as how much attenuation it has. The best thing you can do is decide where you want to mount your antenna, where you want your scanner and the length of coax you need to connect the two. Then select the type of coax you need in order to keep the coax's transmission loss to an acceptable level. Loss is measured in db and less is more (less db loss is more signal). An increase of 3db loss means half the signal so reducing the loss by 1db means a really nice increase in signal.

I know I didn't answer your questions but there are just too many variables.

 

[petnrdx]

And keep in mind that this also depends on which frequency band you are most interested in.
Loosing "half' the signal doesn't mean you won't hear anything.
Might not make any difference at all.
Shorter runs and NO LOSSY ADAPTERS are the key.
Larger coax is generally better.
Example, plain old RG-58 looses around 10 dB with 100 ft run at say 450 mhz.
The "half-inch braided" cables like 9913 or LMR400 would be around 3 dB loss for the same length and freq. So close to a 6 dB improvement.
Depends some on what brand and whose "propaganda" you want to believe. All those values are kind of plus or minus a bit.
So, with really long runs, ya' probably wanna' go with one of the RG-8, RG-214, 9913 etc kind of cables.
I don't care much for LMR but a lot of people do.
Just my opinion, but I find that it is hard to "hear" the difference in a 3 dB improvement with FM.
That said, if you can pick up 3 or more dB of improvement, it might be worth it to you. Depends on how much you want to spend. Especially if you are really on the fringe of a coverage are.
When listening to 700/800/900 systems, you probably have to sneak out ever bit of signal you can get.

 

[Blackink]

My BCT15x scanner is connected to a ST2 antenna using 50' of RG6 coax with F connectors.

I also had to add about 10' of some coax cable that was left from the old Adelphia cable days, similar to RG6 but I'm not sure.

I listen mostly to 150-450mhz range and all comes in good.
I can pick up frequencies 60-75 miles away easily.

Hope this helps....

 

[teufler]

Coax Loss Calculator
the above is a easy chart to figure out coax length and line loss. First any external antenna, is better than the built in radio antenna. As you improve you receive signal, you will also improve your background noise and other activity that shares frequencies with who you are really interested in.

 

[ofd8001]

A little something extra to add. . .

Be sure to wrap the antenna connection with water resistant tape to lessen the potential of rain infiltrating the connection. Moisture can lead to corrosion and degraded connections, and loss of signal. Also leave a little extra cable at each end in case connections have to be repaired down the road.

 

[teufler]

As Old8001 says, prepare the ends for water. Some of us make a coil at the top where you screw the coax into, its called a drip loop.just make a loop with the coax and tie it to the mast or support. Normally it is a piece of mind connection but it can save your coax if you get water into it. Water should stay in the drip loop. If its a warm day, the coax can be unscrewed and let hang from the support. The water will run out and the heat will dry out the coax to where you can use it again. Off the air for a couple of days but it beats buying new coax.

 

[Dfgarland]

Thanks everyone for your help