[andy.s.lee]

Originally Posted by herplace

I'll just spring for this RG6 or RG11 you mentioned. If I understand your guidance: Putting RG11 into the run will assure the best practical 30' loss protection?

In most cases, it's not necessary to resort to RG11. If the length of cable from your attic to your TV is only say 40 feet, then the difference between RG6 and RG11 is only going to be about 1 dB. Hardly worth it considering that RG11 is more expensive and more difficult to work with (needs different F-type fittings, is stiffer, is heavier, has a larger bend radius, etc.).

Also, if you use a pre-amp, then the line loss after the amp doesn't really matter.

I think the ideal setup for your situation is a roof mounted antenna with a pre-amp and RG6 for all the connections in between.

Since WRGB is on channel 6, a full bandwidth combo antenna like the Winegard 7084P seems like a good fit. After the antenna, a few feet of RG6 would then connect into a pre-amp (like a Winegard AP 8275). More RG6 would connect from the pre-amp into your house and ultimately into the power injector. And finally, another short section of coax can connect between the power injector and your receiver.

If you have a chimney that rises above the roof by a couple of feet, chimney straps are a good way to mount the mast without having anything go into your roof (as opposed to something like a tripod mount). Eave mounts are another alternative.

When I get brave enough to explore the attic what kind of things ought I look for in the way of alignment of the various parts of the antenna? I wonder how perfect all those bristles at the back end of the boom have to be in terms of the horizontal plane and the distance apart from the boom to the tips. Should the antenna boom be absolutely "level" for starters?

For combo antennas like yours, there are two sections.

The long elements in the back are a "log periodic" style of antenna designed to pick up VHF channels. This type of antenna is sensitive to the elements having the right length for optimum "resonance" on the desired channels. As long as the elements are not broken or have any shorts (electrical contact in places where there should not be any), then the antenna will probably work fine. It's not critical to have all of the elements perfectly flat within the same plane.

The short elements at the front of the antenna form a "Yagi" style antenna designed to pick up UHF channels. This type of antenna is sensitive to the length and spacing of the elements. These elements form a kind of "traveling wave conduit" that delivers the optimum signal to the sensing elements in the middle of the antenna. In order for this portion of the antenna to perform optimally, the elements should be aligned with each other and maintain their proper spacing intervals.

In most cases, an antenna that is slightly bent out of shape will still perform fine. It usually requires something significant (like a broken element or a short) to have a noticeable change in antenna performance.

Conductive objects in the space around an antenna (like plumbing, metal bracing, wire mesh, foil-backed insulation, ducts, appliances, etc.) can have just as much influence on reception as the antenna itself. In order for an antenna to perform up to its potential, it needs to be free of these other obstacles.



TV signals are horizontally polarized. This means receiving antennas will perform optimally when the elements are horizontal. However, it's sensitivity to this is pretty low. You can have a 10º or 20º tilt and barely notice any change.

Would you happen to know if 100+ year old slate seriously deflects or impedes signals. I'm getting the notion that all the variable influences like the exact angle of a roof make compensation really tricky under a roof.

Sorry, I don't know. Also note that RF absorption rates can vary with frequency, so determining if it's transparent/translucent/opaque can get complicated. Trial and error is the best tool we have against so many unknown variables.

I won't rule out a rooftop experiment some fine day.

It's good to stay open to ideas. A rooftop antenna does seem like the best solution in your case, so I do hope you'll give it a try someday (when the weather is nice).

Best regards,
Andy