Signal loss through coax?

[xpawel15x]

I am using a 7' RG-58 coax cable antenna mount to mount my ducky higher in my room. The reception is better but am I loosing any signal through the coax?

 

[JnglMassiv]

The reception is better...

That's all that matters. The answer is that there is some loss in any physical medium, including coax cabling. The question becomes whether the increased antenna height and/or favorable position allows for a better signal even after the added losses due to cabling, adapters, etc. In your case, you appear to be ahead.

 

[Gooser]

I have three scanners set up with antennas hanging with cheapo RG-58 coax.

1> BCT15 with 15' of coax hooked up to a RS800MHz antenna in the window.

2> Pro-97 also w/ 15' ft hooked up to a Nomad wire antenna for VHF (planes, trains, and some automobiles (CHP)) hanging outside off a roof eave.

3> When I'm not using it elsewhere, a BC246T hooked up to a Max Systems 800 antenna w/ 25' of coax in a window. (I know I need to shorten that length...but it still works better for trunking than anything else I have right now).

Both systems with their "800" antennas still pick up VHF, but the Radio Shack does better wide band while the Max does better on 800.

Anyway, while I know there is loss, the return of improvement of the various antennas being attached directly to the radios is still better. So I stay with it.

Like JM said..."That's all that matters" .

 

[xpawel15x]

I have three scanners set up with antennas hanging with cheapo RG-58 coax.

1> BCT15 with 15' of coax hooked up to a RS800MHz antenna in the window.

2> Pro-97 also w/ 15' ft hooked up to a Nomad wire antenna for VHF (planes, trains, and some automobiles (CHP)) hanging outside off a roof eave.

3> When I'm not using it elsewhere, a BC246T hooked up to a Max Systems 800 antenna w/ 25' of coax in a window. (I know I need to shorten that length...but it still works better for trunking than anything else I have right now).

Both systems with their "800" antennas still pick up VHF, but the Radio Shack does better wide band while the Max does better on 800.

Anyway, while I know there is loss, the return of improvement of the various antennas being attached directly to the radios is still better. So I stay with it.

Like JM said..."That's all that matters" .

First of all, thanks for the response.
How do you keep the 800 mhz antennas to the window? Did you simply tape it to the window? That's what I have done. Thanks

 

[zz0468]

I am using a 7' RG-58 coax cable antenna mount to mount my ducky higher in my room. The reception is better but am I loosing any signal through the coax?

Not enough to worry about. It would take about 3 db to barely notice a difference if you're comparing, 6 or so db to say 'yep, it's a bit weaker' and probably 10 or more to say hey, something is wrong here.

It's 20 DB from .1 microvolt to 1 microvolt.

 

[57Bill]

Someone posted this when I had a question about signal loss, and I found it helpful:
www.timesmicrowave.com/cgi-bin/calculate.pl

 

[key2_altfire]

Loss also depends on the frequency. The higher the frequency, the more the loss. (Higher frequencies will tend to jump from the center conductor to the shield more easily.)

Higher quality coax will usually have a flatter loss curve from lower to higher frequencies. Times Microwave LMR-400 is a popular cable here (or any LMR-400 for that matter) due to its nice price performance and low loss.

 

[k5uss]

Per the Times Microwave calculator:

7' of RG-58 coax is giving you a loss of the following:

27MHz - .2 dB
48MHz - .2 dB
150MHz - .4 dB
450MHz - .7 dB
850MHz - 1.0 dB
1200MHz - 1.2 dB

You have nothing to worry about. If you made a simple ground plane antenna for the main freq you monitor, or bought something made for scanning, and then elevated it as you have the duck, you would be even more amazed at the reception you get.