No Signal

AndyTiedye · 02-20-2009, 11:56 PM

Our pursuit of DTV is reaching the "extreme measures" stage.
TVFool says we should have plenty of reception:

But TVFool does not take trees into account:

We can pick up about 8 analog stations, but no digital stations.
All the really strong stations are low VHF. High VHF is weak.
Analog UHF is unwatchable with a roof antenna.
The only way I could watch it at all was to hang a TV antenna
high up in the redwoods. After getting no signals from roof height,
I tried hanging it from the tree for digital.

AndyTiedye · 02-20-2009, 11:59 PM

Part 2
The antenna is a 91XG, it is up 50'. There is 100' of new RG6U.
I aimed it carefully at Sutro Tower:

but it was all for naught:

Tried Channel Master and Zenith STBs. Tried with and without Antennacraft amplifier.

Tim58hsv · 02-21-2009, 04:12 AM

Yagi's are the best antennas for long range reception but very very directional. Maybe too directional for your situation. Something like a db8 may work better for you since they aren't as directional and they are rated at something like 60 miles.

I base that on the results of my antenna set-up in the attic. I have a db2 and db4 that works great up there. There's also an old top of the line Radio Shack uhf yagi laying up there that's not hooked up because when I tried it out about two weeks ago, it just wasn't any good at picking up channels compared to either db antenna.

Yup, a 2-bay bowtie antenna even works better in an attic than a top of the line Radio Shack yagi will, at least from my experience.

A db8 might be worth a shot as long as you can take it back if it doesn't work.

AndyTiedye · 02-21-2009, 01:08 PM

How directional IS a 91XG?

Jay · 02-21-2009, 03:54 PM

Quote:

Originally Posted by AndyTiedye

How directional IS a 91XG?

According to Antenna's Direct own Product Description:

Quote:

The reflector grids create an improved front to back ratio with shorter construction while the 91 elements truly make it one of the highest gain UHF antennas available.Although the 91XG is one of the highest gain UHF antennas made, it is also very directional. If you live more than 60 miles from the transmitters, you must get as much elevation on the antenna as possible. Even with its great gain, it cannot pick up signals blocked by the curvature of the earth.

The DB2, DB4, and DB8 are still considered directional antennas because of their flat desgin as well.

That 50' mounting height in the trees was a great idea, but I'm willing to bet there's still a good amount of deflection. How many feet distance in cable total between the antenna and the converter? 100' total?

Are their close trees directly in the signal path of your current mounting position?

I could never get tired of looking at those redwoods everyday

cowboyup4christ · 02-22-2009, 05:13 AM

The red woods would not cause as much deflection as a oak or other non evergreen tree. place the 91-xg on a pole about 30 ft connect quad shield coax between it and the tv if over a 100 ft place a wineguard 4800 pre amp on the mast under the antenna. tilt the antenna to fifteen degrees on the mast see if this helps hanging it in a tree allows it to sway and causes the signal signal not to lock. mount it sturdy at 30ft or maybe 40ft

TonyT · 02-22-2009, 09:53 AM

Definitely like the CM 7777 for preamp setup, but this is a tough one, especially with not being able to get the antenna mounted higher than the trees. I mean, how can anyone actually mount any taller than a forest of redwoods??

Your 91XG would be perfect if you could get a clear line of site mounting position. Multipath seems like the main problem here.

cowboyup4christ · 02-22-2009, 12:04 PM

Quote:

Originally Posted by TonyT

Definitely like the CM 7777 for preamp setup, but this is a tough one, especially with not being able to get the antenna mounted higher than the trees. I mean, how can anyone actually mount any taller than a forest of redwoods??

Your 91XG would be perfect if you could get a clear line of site mounting position. Multipath seems like the main problem here.

OK the 91-xg can be tilted up 15 degrees to point over the horizon of the trees to give better signal

if you could find a gap in the trees at 344 degrees tilt it up 15 degrees an see if you can get a signal then.

AndyTiedye · 02-22-2009, 10:57 PM

Quote:

Originally Posted by cowboyup4christ

place the 91-xg on a pole about 30 ft connect quad shield coax between it and the tv if over a 100 ft place a wineguard 4800 pre amp on the mast under the antenna. tilt the antenna to fifteen degrees on the mast see if this helps hanging it in a tree allows it to sway and causes the signal signal not to lock. mount it sturdy at 30ft or maybe 40ft

I had it up 25' (from the ground) on a pole with 25' of coax (which is why I
only went up 25' that time), angled up and got nothing. That's why I tried
putting it up in the tree. I can go up to 40' on that Army surplus field tower
I have been testing with, but will that improve the signal?

In either location I get 0% signal strength on every channel except 19, which comes up to about 30% intermittently.