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Discussion Starter · #1 ·
My sammy 160 has the signal drop in and out strength 70 then 0 for no apparent reason. I have an outdoor radioshack U75-r UHF antenna. Stations 40 miles away and hilly terain. Think an amp would help. Also unable to pick up all the digital stations in my area. If so what amp. Please help.
 

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I don't think an amp or preamp will do you much good. What will probably

help the most is to raise your antenna and try re-aiming your antenna.

Sounds like your getting multipath problems from them there hills and raising your antenna should help with that.
 

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Discussion Starter · #3 ·
Thanks for the reply, this OTA is demanding. Looks so goooooood...... when it works!
 

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Actually, an amp could help, but only one with a real low noise factor. I've had very good luck with that antenna and both a CM 7775 pre-amp or a RS 15-1171 "Cable Distribution Amplifier". Everything else I've tried in the RS catalog is junk (for digital reception...). If you go with the 1171 you need to have it fairly close to the antenna. It starts to not add anything when the distance is greater than about 25 feet or so. The CM 7775 separates the amplifier portion from the power supply so that you can mount the amp part on the mast with the antenna and then the PS farther down the line, where power is convenient. It then feeds the power back up the line to the amplifier.


-- Gary
 

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Fairly strong, but unstable reception sounds like multipath or some other interference problem. I don't think an amp/preamp would help.


You probably need to re-aim your antenna. Or try changing the TILT, either pointing slightly up or down. Raising (or lowering) the antenna a few feet may help. The antenna may also be in a "dead" spot, similar to how FM reception in the car can be intermittent when stopped in hilly terrain. Moving the car only a foot or so improves reception. Same for TV. You may need to reinstall the antenna in a different spot on the roof.


Or, you may need a more directional antenna, precisely aimed.
 

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While I agree that antenna placement is probably the singley most important factor, I have also found that when using that antenna in particular, the 1171 or 7775 will almost always help the receiver hold lock through temporary increases in multipath activity for distances greater than 25 mles.


With digital reception, gain is not really critical as most receivers have little problem locking onto very weak signals as long as there isn't any multipath to deal with. Multipath will give a digital receiver fits, however, even if the signals are strong. With weaker signals a low noise amp will help the receiver "see" a slightly bigger difference between the real signal and the multipath and allows it to remain locked during periods of increased multipath.


The "numbers" on your receiver are not a measure of signal strength but are an indicator of how well the receiver is able to "see, and lock onto, the real signal above the noise and multipath "echos". When choosing an antenna, its "directionability" is more important than gain. That is why even a "low-end" model like the RS 2160 (U75R) will work as well the more expensive high-gain variety.


-- Gary
 

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Had the same problem when my antenna was inside, put up and outside antenna and I am betting that your problem will go away without a preamp.


Jim
 

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Quote:
Originally posted by GGoodrum

The "numbers" on your receiver are not a measure of signal strength but are an indicator of how well the receiver is able to "see, and lock onto, the real signal above the noise and multipath "echos".
Yup. While "signal strength" really does measure signal strength for satellite signals (since attenuation is the only impairment), for OTA it's really measuring "signal quality"/


When the "signal quality" meter jumps around alot without ever giving a picture, that's usually an indication that the receiver is unable to acquire carrier lock. Signal level probably isn't a problem, a pre-amp probably won't help, but it's impossible to say without knowing your receive level. Short if looking at the signal at your location with a spectrumn analyzer, it's hard to say. But if you try the preamp, don't be surprised if it doesn't help.


A better (more directional) antenna, and/or a better receiver (longer equalizer and thus better able to deal with multupath), are probably what you need.
 

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Quote:
Originally posted by wvudrj
Thanks for the reply, this OTA is demanding. Looks so goooooood...... when it works!
I think this fellow has a similar situation to what I have. I'd say from the above comment he gets a lock.....just can't maintain it for whatever reason or reasons.
 

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Discussion Starter · #10 ·
I just raised my antenna by 15 feet and I now get the NBC affiliate with a signal of 79 and no dropouts. The analog nbc comes in without ghosting so I assume it is a multipath problem. The curious thing is that the towers for abc cbs are on the same mountain as NBC but I have never come close to picking up a signal for them even with my 15 foot monstrosity antenna. The other analog channels have ghosting issues. I forgot to tell you I now pick up digital PAX (big deal).
 

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Discussion Starter · #12 ·
CYclone the question is, was your problem signal strength or multipath?

How much was the RS 15-1171 and how dificult to install. Any help appreciated.
 

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Discussion Starter · #13 ·
Also can you use this when your direct tv cable is diplexed with your ota signal?
 

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Antennas are a trial and error affair. A preamp and or rotator may help with multipath and weak signals. Many stations are transmitting at low power and may be the reason you can't get those channels. I would suggest that you check out the local reception thread and see if there are any post's on you area to get any info on signal strength and antenna

setup's that others are using.
 

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Discussion Starter · #15 ·
I am the guy that started the local reception thread in my area and I am the guy that does most of the posting so I am kind of alone here.
 

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I see several references to the RS 15-1171 amp, but I did not see it on the RS website. Does anyone know if it is still available?
 

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Once again, the geniuses at RS have discontinued something that actually works for HDTV. There is some hope in that they have "re-badged" the only other items in their catalog that worked with digital reception, the ubiquidous Double Bow-Tie and the old 15-1260 Amplified Indoor Antenna, which is now the 15-1880 "HDTV Amplified Indoor Antenna".


I haven't tried it but I think the 4 output distribution amplifier that looks just like the 1171 has the same amp. You might try it and terminate the unused outputs.


-- Gary
 

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GGoodrum:


maybe I'm blind, but I do not see a "4 output distribution amplifier " on the RS site either. Only 4-output I see, is for component and s-vid.
 

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You're right, it's gone too. I just saw some at my local store yesterday so that's why I thought they were still in the catalog. Amazing.


You might check at a store.


-- Gary
 

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Thanks Gary:


I'll take a look.
 
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