# What signal level does it take for 921 to lock OTA



## IamtheEggman (Sep 21, 2004)

Just got my 921 going and have been trying to get my locals OTA. Got 2 out of 3 but the NBC affiliate won't lock for more that a few seconds. The Signal goes from 70 to zero, to 70 and then 0.... I called WLBZ, Bangor, Maine freguency 25, VHF and was told they are only at half power but I should be able to get it where I am located. I have a Channel Master mounted on roof with rotator. I gues my question is at what signal level should I get a lock. What about amps, do they work or do they just amplify noise?


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## boylehome (Jul 16, 2004)

IamtheEggman said:


> Just got my 921 going and have been trying to get my locals OTA. Got 2 out of 3 but the NBC affiliate won't lock for more that a few seconds. The Signal goes from 70 to zero, to 70 and then 0.... I called WLBZ, Bangor, Maine freguency 25, VHF and was told they are only at half power but I should be able to get it where I am located. I have a Channel Master mounted on roof with rotator. I gues my question is at what signal level should I get a lock. What about amps, do they work or do they just amplify noise?


Something is wrong if the signal goes from 70 to 0. This is too great of fluctuation. I've been able to lock on signals of just over 55. Are you sharing your OTA antenna with something else (splitter in line)? Do you have a bad connection? My bet is that you have problem with one of your connectors. Give them a good check.


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## David_Levin (Apr 22, 2002)

Sometimes that type of oscillation is caused by multi-path. An echo of the original signal is hitting something (mountain, tall building), bouncing around, and hitting your antenna offset from the original source. The noise from the bounced signal (still at the same frequency), drowns out the primary.

I assume the channel master is a uni-directional antenna. Does it get any better when you rotate it?

Some people have reported amps to help. Once you've checked all you cables, it couldn't hurt to try.


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## Mark Lamutt (Mar 24, 2002)

Sounds like a multi-path problem to me as well. We know all about that in Denver here. And, as for signal strength, to keep a stable picture with minimal breakups, you really need about 60 or so with the 921 (at least that's been my experience).


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## IamtheEggman (Sep 21, 2004)

Not sure how it could be a connection when other stations lock at high signal. Its only one particular station that doesn't lock and oscilates(sp?) between 0 and 70, I'm reasonably confident in my connections, I used Thomas and Betts connectors with their tool. I'll check again though

Multipath is interesting, The stations that come in sit high on a mountain(well hill for you Colorado residents ) and I'm barely above sea level here on the coast of Maine. They come in great. The station that doesn't has a small tower (120 ft) on a smaller hill about 17 miles from me. I'm not sure if there any other hills in the way but no buildings other that a 2 or 3 story house, maybe a church steeple. The signal comes in a couple of different spots when I rotate the antenna. I have a rotater that I can really bump it in small increments so fine tuning it is easy but no avail. I might spring for a Amp but someone said I might overpower the good stations and they'll drop out??

Thanks for the help

Jon


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## JM Anthony (Nov 16, 2003)

Mark Lamutt said:


> Sounds like a multi-path problem to me as well. We know all about that in Denver here. And, as for signal strength, to keep a stable picture with minimal breakups, you really need about 60 or so with the 921 (at least that's been my experience).


Multipath gets my vote as well as I've been experiencing the same thing in Seattle. An amp won't help solve that one.


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## paulcdavis (Jan 22, 2004)

I've also found that my multipath problems vary with the weather. On clear days I'll have a signal above 100, but if there is fog, the signal strength drops below 80 and on some stations it oscillates from 0 to 70 and will not lock. Since I'm in the San Francisco Bay area, fog is not unusual, so I always have to make duplicate recordings from OTA stations and the LIL sat channels.


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## Mark Lamutt (Mar 24, 2002)

The only way to fight multipath is to use a more directional antenna than what you have now. Jon - when you say you can pick up that ocillating station with the antenna pointed a couple of different directions, that confirms that you've got a multipath situation. One or both of those directions you are picking up a signal reflection off of something. You didn't say exactly what antenna you have, but whatever it is, you need one that is more directional so that it will reject the signal reflection that it's receiving.


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## IamtheEggman (Sep 21, 2004)

I have a channelmaster 3018
www.channelmaster.com/images/3018.jpg


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## boylehome (Jul 16, 2004)

IamtheEggman said:


> I have a channelmaster 3018
> www.channelmaster.com/images/3018.jpg


Pre-Amps can be very tricky with digital signals. They amplify all sorts of frequencies and that can sometimes negate the digital information. An in-line amp is a better way to go. If I recall, you say that you are having problems with just the one channel (25?). That may be the week spot for SWR for on your Channel Master Antenna. My antenna is worst for channel 20. There are other factors including multi-path that can affect your signal. A cell tower, nearby microwave towers too can be a problem. Is there a remote station transmitting around the same channel frequency from a location close to the location where the channel your having problems with is transmitting? If I may ask, do you get the signal fluctuations with the other channels? I had a bad balen , just replacing it made my antenna work 45% better. Do you have incoming cable or other antenna where the output isn't capped off? It might even be worthwhile to contact the station to see if they are having transmission problems. Keep us posted on your progress. Hope this helps.


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## pculley (Dec 23, 2003)

I also had this problem (signal jumping from 0-100). It seemed to vary as to cause, sometimes when the wind blew it would be very bad, but even when all was still I would still get occasional jumps. A friend suggested that multipath was probably my problem, but also suggested that it might be a reflection off of my roof. Since I have foil backed plywood underlayment, it makes sense that it might reflect. I also had the antenna located in a position such that the signal would hit the roof and have only a shallow angle to hit the antenna. In any event, I repositioned the antenna 10 feet higher (one more Radio Shack antenna mast extension + guy wires for safety) and the problem went away completely. I earlier had tried to rotate it, but had little success.

At the very short UHF wavelengths, even a small shift in antenna position might be enough to move it in or out of a "null" caused by a close by reflection.


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## Altaman (Sep 7, 2004)

Another thing to check is your connections...I had a problem with signal strength fluctuations (also pixelization) when I had second dish installed at my home. After switching cables, I found the problem happened at the other TV. I disconnected cables and found that when the installer installed the cable at the dish, he cut too deep and the copper wire was barely hanging on to the coax. Switched cables and have not had a problem since.

Alt


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## fox200 (Mar 21, 2004)

IamtheEggman said:


> I have a channelmaster 3018
> www.channelmaster.com/images/3018.jpg


Use a Channel Master 4248 with rotor to fine tune your signal. No pre-amp.
You can use a distribution amp in the house to help with signal lose from long cable or poor cable quality. It's the best setup for deep fringe, hills, and tall buildings. This is what I use and I get outstanding performance from 40 miles away with hills between me and the transmitter.

fox


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## BobMurdoch (Apr 24, 2002)

Does anyone know of any mom and pop type retailers that offer high end antennas/amps and include installation in the Central Jersey Shore area? The local Best Buys and Circuit Citys only offer the Terk bar type antennas which I am told are useless for receiving digital signals this far away from New York (42 miles) and Philly (62 miles).


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## jamullian (May 7, 2004)

I have the same problem with an NBC channel in San Diego - since they went to full power. In my case the problem might be caused by there being an adjacent analog channel (the digital is 40, translates to 39-1) and the analog is 39. The 921 seems unable to discriminate between them correctly. My only solution was to get a standalone LG tuner, that only accepts digital signals, and has no problem.


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