The best antenna coax available?

[day67]

Good question. What are AK ers opinions on what the best coax (shielded? quad shielded? other?) cable is for running, say, a < 50 foot run from an attic yagi-type to a tuner with a coax connection. Just wondering. There is also another regular RG-6 type coax running off the antenna to a different part of the house. What's the most important factors here, length, shielded or not, other sources of interference?

I don't know a lot about antenna cable so one might think the best cable for, let's say, rca interconnects would also be the best for antenna -- necessarily true? Thanks in advance!

 

[Hepcat]

RG-6 is fine. Use the F connectors not RCA's.

 

[aabottom]

...
What's the most important factors here, length, shielded or not, other sources of interference?
...

The most important factors are impedance matching from the antenna to the tuner, and shielding from electromagnetic interference EMI.

We need to know what kind of connector is on your tuner and at the antenna. Your tuner likely has a 75 ohm female F connector and/or 300 ohm twin lead connections. Some receivers/tuners have both.

The antenna connector (with matching transformer) should match with that of the receiver/tuner.

RG-6/U cable and an F connectors are likely among the best solutions.

From Wiki, “The F connector is inexpensive, yet has good 75 Ω impedance match up to 1 GHz and has usable bandwidth up to several GHz”.

EDIT: Page 2 of this RadioShack antenna manual maybe useful to you. It shows how to hook up RG-6 or Twin-Lead Cable.
http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/1500274_PM_EN.pdf

 

[whoaru99]

Good question. What are AK ers opinions on what the best coax (shielded? quad shielded? other?) cable is for running, say, a < 50 foot run from an attic yagi-type to a tuner with a coax connection. Just wondering. There is also another regular RG-6 type coax running off the antenna to a different part of the house. What's the most important factors here, length, shielded or not, other sources of interference?

I don't know a lot about antenna cable so one might think the best cable for, let's say, rca interconnects would also be the best for antenna -- necessarily true? Thanks in advance!

Belden 7915A RG-6 is a great coax choice and is inexpensive. Tri-shield design with better noise rejection than quad.

 

[Grainger49]

I am fond of Belden 89259. Single braided shield with a stranded center. The specs are pretty good, low capacitance, high velocity of propagation. It is RG-59, not as beefy as RG-6, but easier to pull. If you are not running next to AC lines triple shielding is not necessary. Cross any AC you must cross at 90 degrees.

 

[sgmlaw]

The best in an FM down lead application is shielded 300 ohm twin lead. Exceedingly hard to find this anymore, especially in a quality build.

Among coaxial types, RG-11 is best. But as stated, any RG-6 variant will be fine for all but the longest runs at these frequencies. You don't need QS unless you are running it in very high interference areas. You don't need sweep test certified cable, unless this is a run where satellite or extended frequency CATV signals are contemplated.

I do not recommend RG-59 in any quality OTA drop, or for any distribution network generally unless the attenuation rate can be adequately managed. RG-59 is suitable for short runs in strong signal situations, only.

Avoid amplification.

 

[day67]

Thanks for the advice. The tuner has what i beleive is called a female "F" connector and terminals for the twin lead 300 ohm. Unusual. Off the antenna in the attic is the twin lead connection to a transformer/coax connector. Tri shielded better than quad shielded? Would'a thought "more is better" so I learned something.

 

[aabottom]

Thanks for the advice. The tuner has what i beleive is called a female "F" connector and terminals for the twin lead 300 ohm. Unusual. Off the antenna in the attic is the twin lead connection to a transformer/coax connector. Tri shielded better than quad shielded? Would'a thought "more is better" so I learned something.

Take a look at page 2 of this RadioShack antenna manual. It shows how to hook up RG-6 or Twin-Lead Cable.
http://www.radioshack.com/graphics/uc/rsk/Support/ProductManuals/1500274_PM_EN.pdf

"A half wave dipole antenna is nominally 75 ohms while a half wave folded dipole antenna is nominally 300 ohms. The two previous examples indicate why we have 75 ohm coaxial cable and 300 ohm ribbon line for TV antennas" (see ANTENNA BASICS).

Likely, you have a 300 ohm antenna. The "connection to a transformer/coax connector" matches the nominal 300 ohm impedance of the antenna to the impedance of the RG-6 coaxial cable (75 ohms). The RadioShack manual above also shows the alternate methood, which is connect the 300 ohm twin lead directly to the antenna without a transformer.

 

[whoaru99]

Thanks for the advice. The tuner has what i beleive is called a female "F" connector and terminals for the twin lead 300 ohm. Unusual. Off the antenna in the attic is the twin lead connection to a transformer/coax connector. Tri shielded better than quad shielded? Would'a thought "more is better" so I learned something.

This particular tri shield, not necessarily all tri shield. The key to this one is a shorting fold in one of the foil layers that basically seals the small gap present at the point where most other shields merely overlap.