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Old 3-Mar-2010, 2:31 AM   #1
WaaCC
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Join Date: Mar 2010
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Antenna selection help

http://www.tvfool.com/?option=com_wr...b7c85b025cff60

Replaced roof shingles, so while at it decided to replace large old antenna (15+ yrs old, bent stubs, about 10' long).

From antennaweb it seemed like I could get away with something smaller. So here's my setup:
CM 4228 HD roof mounted on 10' pole (30-40' total height)
60' Belden 1994a cable with canare connectors (bluejeanscable)
CM 3418 Distribution Amp in attic
6x live drops ~20-30' each to TVs and tuner cards.
2x spare drops ~20-30' for additional TVs. Terminated with 75 ohm.

The antenna is aimed at the tower at 303 degrees. All the channels I'm interested in are in the green zone, but one set of stations is near 303 degrees and the other at 25-28 degrees.

Daytime reception is good but evenings and specially when it rains I start to get a lot of video blocking on RF 7 & 12, less so on RF 38 & 44.

What do you suggest?
1) Get rid of the distribution amp?
2) Aim the antenna 1/2 between 25 & 303 degrees?
3) Aim the antenna at 25 and add a second antenna (HD7694) pointed at 303?
4) Replace the antenna with a coathanger or other antenna?

The old antenna didn't have dropouts on stations in the 303 direction, but sometimes couldn't pick up the 25 direction.


Thanks in advance for your help.

WaaCC
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Old 3-Mar-2010, 7:30 PM   #2
mtownsend
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Hello and welcome!

The reason you're having problems on channels 7 and 12 is because the 4228 is really a UHF-only antenna. I know that some people tout it's ability to work at high VHF, but it is nowhere near as good as a true VHF antenna.

You can improve the stability on those channels by adding a separate VHF-only antenna like the Winegard YA-1713 or the Antennacraft Y10-7-13. Your VHF and UHF antennas should be combined through a UVSJ (don't just use a regular 2-way splitter).



I would recommend keeping the antenna pointed at San Francisco. The closer transmitters to the north-east are so strong that they should be able to get in through the "side" of your antenna. It doesn't sound like you've been having any problems from those stations, so all you need to worry about are the San Francisco and San Bruno stations.

The strongest channels on your list are in the range high enough to cause overload on your distribution amp. Normally, with an 8-way or 6-way split, it's a good idea to use some kind of amplification, but if the amp is getting overloaded, you're better off without it. In this case, it's on the borderline. If there's a long cable between the antenna and the distribution amp, then the signal power might have dropped enough to be below the overload limit of the amp.

If you can, I'd recommend that you try it both ways. Once with a passive 8-way splitter, and once with the distribution amp, and see if there's any difference. If there's no notable degradation with the amp, then you're better off keeping it in place.
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Old 3-Mar-2010, 8:17 PM   #3
WaaCC
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Join Date: Mar 2010
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Hi, thanks for the quick reply.

If I put the YA-1713 up there on the same pole, how much seperation do I need between the two? Which would be better on top? The bottom one may be getting close to the height of the roof peak. Do you think a single Winegard HD7696 would do the job? It has about the same high VHF gain. Maybe it would be too directional to pick up both tower locations?

I'll try some non-powered splitters and see if that has any effect.

W
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Old 4-Mar-2010, 12:20 AM   #4
mtownsend
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Quote:
Originally Posted by WaaCC View Post
If I put the YA-1713 up there on the same pole, how much seperation do I need between the two?
Keep at least about 4 feet between the two.



Quote:
Which would be better on top?
Most people put the UHF antenna on top. UHF is more sensitive to line-of-sight access to the signals. If there are no local obstructions, then the difference is negligible, but just in case there is something partially in the way, the UHF antenna has a better chance of benefiting from height.



Quote:
The bottom one may be getting close to the height of the roof peak. Do you think a single Winegard HD7696 would do the job?
Sure. One combo antenna can be used instead of separate UHF / VHF antennas. The only reason I suggested adding a VHF antenna is because I think a YA-1713 plus UVSJ is probably cheaper than a HD7696P. The VHF performance of either antenna is better than the 4228, so either solution should work.

If you have a 10 foot mast on your roof, it's about the right length to hold two antennas if you opt for the separate antenna solution. If you have the YA-1713 about 4 feet above the roof and then the 4228 another 4 feet above that, you can probably just barely fit both of them on the same mast.



Quote:
Maybe it would be too directional to pick up both tower locations?
No. I don't think so. The closer stations are so strong that they will make it through almost any antenna. If you are getting the north-east stations through the side of the 4228, you will also be able to get them through the side of an HD7696P.
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Old 17-Mar-2010, 1:20 AM   #5
WaaCC
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Reading the web some more, getting some more education before spending more money on antennas. Using the Google Earth data and found that I had the antenna pointed about 10 degrees off from where it should be. Redirected the antenna and found that for the UHF channels the signal strength went up 50% or more as indicated on my plasmas signal strength indicator. The high VHF channels had insignificant increases and with the rains I get dropouts on 7 & 12.
I can locally pick up a HD7694 for about the same as a shipped YA-1713. Do you think the HD7694 by itself will be enough?
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