Better to run 300 ohm or 75 ohm from antenna?

[jmcgee_jr]

I am going to try out a CM-4228 and if it works whats better to run from the roof to my basement distribution block? 300ohm is the flat wire stuff right? I have RG6 for my 75 ohm. Thanks guys.

 

[Pepper]

I didn't know anybody used that flat stuff anymore. No shielding, probably notorious for signal leakage or multipath distortion.

 

[NightHawk]

300 Ohm twinlead (the flat stuff) is a lower loss transmission line than RG6 when installed properly. Additionally there is no balun loss to suffer, at least at the antenna end. The problem is it's difficult to install properly. It requires standoffs and periodic twisting and will not mate to most new OTA hardware without a balun transformer.

Bottom line is it isn't worth it in most installations, particularly if your using a mast-mounted pre-amp.

 

[bnaivar]

Actually, 300 ohm wire is MEANT to have a higher loss than 75 ohm coax. it's original purpose was to LOSE signal between the antenna and the TV. When TV's were first coming out a lot of people were putting up far larger antennas than they needed and overloading the tuners on their TV's. TV installers resorted to the 300 ohm wire to lose a substantial portion of the signal but still have enough for a clear picture.

I didn't believe this story until I tried it and read the difference on a signal level meter.

 

[jmcgee_jr]

That would make more sense due to fact it has a higher resistance factor.

 

[NightHawk]

Actually, 300 ohm wire is MEANT to have a higher loss than 75 ohm coax. it's original purpose was to LOSE signal between the antenna and the TV. When TV's were first coming out a lot of people were putting up far larger antennas than they needed and overloading the tuners on their TV's. TV installers resorted to the 300 ohm wire to lose a substantial portion of the signal but still have enough for a clear picture.

I didn't believe this story until I tried it and read the difference on a signal level meter.

Please tell me you don't really believe that.

 

[NightHawk]

That would make more sense due to fact it has a higher resistance factor.

It doesn't, it has a higher characteristic impedance. Totally different thing. The theoretical loss values for even cheapo plastic twinlead is consistently lower up through channel 83.

 

[Tower Guy]

Twinlead has lower loss but coax is better

Actually, 300 ohm wire is MEANT to have a higher loss than 75 ohm coax. it's original purpose was to LOSE signal between the antenna and the TV. When TV's were first coming out a lot of people were putting up far larger antennas than they needed and overloading the tuners on their TV's. TV installers resorted to the 300 ohm wire to lose a substantial portion of the signal but still have enough for a clear picture.

I didn't believe this story until I tried it and read the difference on a signal level meter.

I wouldn't believe it either. There's something else that caused the higher loss with the twinlead.

However, I'd always use a preamp and coax instead of twinlead.

 

[Pepper]

Well, apparently I don't know squat about this stuff. I figured if twinlead carried signal better than coax, then that's what the cable companies would have used to wire the neighborhoods.

Then again, which is more expensive for a given length?

 

[NightHawk]

Twinlead is simply too difficult to install properly. It's completely impractical for cabe TV applications.

 

[Jim5506]

In the early 70's I lived in Carlsbad, NM. We had one of those old bedspring looking antennas on a 40ft mast atop a house that was about 20ft AGL with a rotator above the last section of the mast, so the center of that 5X5 antenna was about 60-65 ft above the ground.

We had to replace the twinlead on that thing every 3 or 4 years due to weathering. It was no fun at all, but we often pulled in signals from 150-180 miles away in the evening, and our "locals" which were 70-80 miles away on channels 8 and 10 were clear as a bell and with good color.

I wish I still had that old antenna, I often pulled in channel 28 out of Lubbock (180 miles), and listened to an FM station from Abernathy (20 miles N of Lubbock) with regularity. It seemed to be able to bring all frequencies, I could get Channels 2, 7, and 9 out of Midland/Odessa too (150 miles).

I also DXed stations from California and Florida with that setup.

If you're adventrous you can install sheilded twinlead and have the best of both worlds, but dont forget to twist it to cancel out any signal picked up in the wire.

 

[dfergie]

I live south of Carlsbad, I haven't tried twin lead in years, but I might do it as I have had poor luck with coax...

 

[Jim5506]

I wish I still had that antenna, but high winds brought the tower down several times and UV got the little plastic insulators. There's probably still pieces of it at my dads house. Maybe I'll try to build one from the parts. I've never seen an antenna with similar performance, the twinlead helped a little.

I've seen pictures of them on the internet, but no plans or samples. Mine looked like this one but without the reflector screen on back, just 12" standoffs from the backplane.

 

[jmcgee_jr]

My local "TV" guy tells me that the 4228 isnt as great as everyone says it is. He think the winguard 7228 or something like that is better. Plus he thinks the wineguard pre amp is better then the 7777 CM? What do you guys think.

 

[ncted]

The installer that put up my CM 3019 told me the 4228 was not good enough for my location, but I was able to pull in all 4 HD networks with the 4228 indoors while I am only able to get 3 with the 3019. I think perhaps it isn't as directional as the 3019 which is my problem. I know nothing about the 7228 or the 7777, but the 4228 seemed to work well in my odd-ball setup.

Ted

 

[roashru]

I use 300ohm (ultra low loss type) antenna wire and all coaxial cable for anything radio related both have their advantges. for this ota hdtv forum readers here should only use 300ohm (ultra low loss type) antenna wire to connect multiple antennas together. the 300ohm wire run between antennas must stay away from the pole about 4 inches. connect the bottom antenna to a 300ohm to 75ohm transformer then to coax or an outside preamp end make sure everything is water sealed!

long wire runs
coaxial cable close to metal pole or large grounding objects: good
300ohm antenna wire close to metal pole or large grounding objects: bad (any length)

 

[Claude Greiner]

I remember when I was like 10 years old and I ran cable to my room because I was sick of rabbit ears. I got one of those 75/300 ohm transformers and ran (2) 22 gauge wires accross the carpert with duck tape.

Worked nice, until my mom got sick of seeing the wire and made my dad drill a hole to run radio shack coax cable. I remember buying the cable which cost me $20, which was alot of money to me back then!

 

[dfergie]

Come to think of it I have not noticed(nor have looked) for the old 300 ohm cable in a while, but it is an idea that I will not let go of...

 

[yumagah]

Boy, this is resurrecting an old thread, but I just got some good results from 300 ohm antenna wire. I have satellite in my living room and wanted to run the receiver output upstairs to bedroom. (No need for 2 tuners - only one tv watched at once.) The place I'm living is going to need a hole drilled in the floor to get wiring upstairs and it's gonna be awhile before I get to it. For a temporary fix I ran 300 ohm from one window to the next floor, about 16 feet in all. The results are so good I may never get around to drilling the floor. The 300 ohm is less noticeable outside than the coax already out there.

 

[Larobpra]

I remember when I was like 10 years old and I ran cable to my room because I was sick of rabbit ears. I got one of those 75/300 ohm transformers and ran (2) 22 gauge wires accross the carpert with duck tape.

Worked nice, until my mom got sick of seeing the wire and made my dad drill a hole to run radio shack coax cable. I remember buying the cable which cost me $20, which was alot of money to me back then!

When cable first came to our town they charged extra for each TV you had hooked up. I tapped off the cable with twin lead wire (because that's what I had available) and ran from the main TV to the kitchen and bedroom. I came home from work one day and my teenaged son met me at the door all bug eyed, apparently 2-3 guys from the cable company came by and had detected signal leakage and unhooked my set-up and told him to tell me NOT to hook it up that way again!