25ft of coax, vs networking - what shall I do?

[Xourque]

Hello guys!

I have my Antennacraft ST2 antenna mounted on a 5ft piece of mast right at the peak of my roof (second story). My computer room + radio nerd room is right under that peak.

Right now, I'm using 25' of coax (75ohm RG6/U AWG18, link: 25 Foot Black RG6 Weatherproof UL Listed Coax Cable) from the balun on the antenna to my SDR.

With that said, do any of you think it would be worth the effort to mount my small ASUS PC in the attic space above the bedroom to save about 15 ft of that coax?

So really...it's (25ft of coax) VS (10ft of coax + SDR-TCP server).

What do you experts think?

Thanks!
Tony

 

[kma371]

it's that coax that's going to kill you.

someone correct me if I'm wrong but I think you need 50ohm not 75ohm feed line.

plus the coax you have is more for TV installations rather than scanner installations. I would switch to rg8 or rg58 with that short of a run.

 

[Xourque]

it's that coax that's going to kill you.

someone correct me if I'm wrong but I think you need 50ohm not 75ohm feed line.

plus the coax you have is more for TV installations rather than scanner installations. I would switch to rg8 or rg58 with that short of a run.

I've read many posts on here where people say for RX-only stations, 75ohm coax won't result in any noticeable receive performance degradation. Also, the matching transformer on my Antennacraft ST2 is 300ohms to 75ohms (that's its stock matching transformer).

 

[SCPD]

It will make no difference.

 

[kma371]

I've read many posts on here where people say for RX-only stations, 75ohm coax won't result in any noticeable receive performance degradation. Also, the matching transformer on my Antennacraft ST2 is 300ohms to 75ohms (that's its stock matching transformer).

OK that may be true.

I'd still use different coax but that's me.

 

[n5ims]

it's that coax that's going to kill you.

someone correct me if I'm wrong but I think you need 50ohm not 75ohm feed line.

plus the coax you have is more for TV installations rather than scanner installations. I would switch to rg8 or rg58 with that short of a run.

The ST2 actually is a 300 ohm antenna that ships with a 300 to 75 ohm balun, which the OP indicates they're using. The RG-6 they're using would actually be better for their installation.

To the OP. I would keep your install as you have it. While you're adding some extra loss, unless you have some very sensitive equipment you won't see any difference between your current 25' and the shorter 10' run. It's like filling the bathtub with water and taking a measurement on how full the tub is. Then you add an extra cup of water to the tub and measure again. There's a difference, but nothing that you can really see.

 

[popnokick]

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Agree. Not only is 75ohm RG-6 OK (even preferred), reducing the length by 10 feet is not going to be worth the effort.

 

[foxtail]

What you want to do is keep the dongle has far away from the pc if you can. I use 3ft usb ext. cable to help cut down on interference from pc. Have two dongles so I put one into a plastic box, air holes, and the other in it's org. case with usb ext. connected to about 100ft of rg6 to ant. 45ft tower. Have not done a side by side compare yet...but will soon.

 

[Xourque]

What you want to do is keep the dongle has far away from the pc if you can. I use 3ft usb ext. cable to help cut down on interference from pc. Have two dongles so I put one into a plastic box, air holes, and the other in it's org. case with usb ext. connected to about 100ft of rg6 to ant. 45ft tower. Have not done a side by side compare yet...but will soon.

Indeed! I'm intrigued to see your results.

Right now, I have it on a 6ft extension, with a ferrite on either end.

I just picked up an FM trap from Radio Shack today and am looking forward to seeing how well it works. I've been hearing some awful FM radio station noise in the 800-900 frequencies (well, in many other places, too).

 

[kq6ea]

I'd think you'd want to keep the ANTENNA as far away from the PC as possible, although using a USB extension cable might help a bit to move the dongle away from the PC.

Once the dongle converts the RF to USB, "interference" from the PC becomes meaningless.

73, Jim