OTA Cabling: RG-6, RG-59, RG-11, Twin-Lead, Crimping, Other Tips

[Rkh63]

Home Depot has the 1 foot flat cable.It is made by RCA,part #CVHD911... $5.98

[RnR]

I recently acquired some new old stock Belden City Color shielded 300-ohm cable as well as a new CM 0264 pre-amp.

What is the recommended way to cable a 300-ohm antenna to that 300-ohm pre-amp (tower mounted) to effectively utilize the shielding the Belden product uses?

[stampeder]

Shielded twinlead is actually pretty simple to use, but I take the added steps of tinning the stripped wire ends with a soldering gun so that the wire doesn't fray when torqued down under the screw terminals of the preamp or similar connector.

[RnR]

Very good!

In regard to the shield though... doesn't that need to be separately grounded in order to actually "shield" the antenna RF?

As the pre-amp appears to only present (2) terminals for the active leads and no accomodation for the cable shield, presumably the City Color cable would have to be seperately grounded somehow (just haven't seen it done). As the packaging says

For greatest reduction of noise interference connect ground wire to nearest effective ground

. I guess I'll have to run a separate wire to effect that upstream of the pre-amp.

[stampeder]

The shielding acts like a Faraday Cage, so grounding it is not necessary. The same thing goes for the shielding in coaxial cable: even if you don't run it through a ground block the shielding still works. I don't knock anyone for grounding in these situations, but its not a showstopper if the shielded twinlead is simply going from the antenna's feed points to the preamp (length of 3 feet or less).

One other thing about your particular preamp: the weatherproof cover on those models has a slot or two for standard sized twinlead to sneak through... you'll probably need to carve the hole e a bit bigger with an exacto knife to accomodate the shielded twinlead, and then waterproof the hole.

Grounding thread:
http://www.digitalhome.ca/forum/showthread.php?t=62265

OTA Waterproofing, Sealants, Adhesives, Paint thread:
http://www.digitalhome.ca/forum/showthread.php?t=104181

[roger1818]

One other thing when using shielded twinlead is to make sure to weatherproof the exposed foam core at the ends. Details on how to do this is best discussed in the OTA Waterproofing, Sealants, Adhesives, Paint thread.

[RnR]

Thanks for the info; good suggestions... all.

[cheap_guy]

I was thinking about using an 8 foot section of 300 Ohm twinlead to connect my 4 bay DIY to my amplifier indoors. I thought that this might help my VHF gain, but I was wondering if its a bad idea or not (ie: would it hurt my UHF).

[stampeder]

Is it shielded twnlead, or is it standard? Shielded is preferable and will do fine indoors. Unshielded can sometimes be a hassle with interference.

Also I'm assuming your preamp has 300ohm input, correct?

[EdT]

The important thing in coax cables is proper termination of the connectors and less the marketing hype of dual vs quad or crimp vs compression ! Military specs calls for crimped connectors and not compression type if that brings any comfort, cheaper crimp connectors wins out !

I used to work as quality assurance manager for a custom cabling shop that produces cables for the International Space Station to DoD and DND contracts.

I see photos in this thread with the dielectric foam still protruding onto the center conductors which is a no-no, use a razor blade or exacto knife and carefully remove the excess dielectric being careful not to score the center conductor, also do not touch the copper core with your hands as this can leave body oils and acids that can oxidize the copper overtime, use a Q-Tip with some alcohol to wipe it before you insert it. Make sure the dielectric does not have any bits of the shielding stuck to it, foam core cables have a tendency to have braiding stick to it, use a small brush or compress air to blow it away and inspect with a 10X loup to make sure that there are no braiding bits in the dielectric. If you are really anal like me, then use a Dremel with a cut off wheel to flatten the copper core so it does not has a burred sharp edge that can damage splitters, amps and your TVs coaxial input, the center conductor should not extend more than 1/8" from the connector.

[EdT]

I haven't seen a thread on here about solid copper core vs copper clad steel core RG-6 cables yet ...any takers ? ...LoL

[stampeder]

Electrically, solid copper is a much better conductor than copper-clad steel core. The VP (Velocity of Propagation) ratings of coaxial cables are expressed as a percentage of the speed of light, and they are much higher with solid copper than with steel core.

Also steel core is not nearly as flexible as solid copper so it can be a hassle to hump around a building or up through tight spots. I only use solid copper RG6.

[EdT]

So which is better RG-9 copper core or RG-6 copper clad ?

From what I understand copper clad is not much of an issue if it is solely being used as a RF conductor due the "skin effect", but if you require current such as a pre-amp or LNB for a dish then copper is a better choice.

[stampeder]

Originally Posted by EdT

So which is better RG-9 copper core or RG-6 copper clad

Did you mean to say RG-9 or was that a typo? RG-9 is 51ohm, not 75ohm.

[EdT]

I meant RG-59 ...typo ...LoL