Inconsistent OTA reception

Gigawatt

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Original poster
Supporting Founder
Mar 12, 2004
14
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Ormond Beach, FL
I am using a CM 4228 antenna with a Spartan 3041DSB pre-amp and have this mounted on a CM rotator approximately 13 feet above my 20' roof line. I am approximately 55 miles from the signal source. Upon initial installation, my reception was flawless. I did have to rotate the antenna to receive between NBC (2.1) and ABC (9.1)/CBS (6.1).

Now the signal is sporadic. I was receiving 93 to 100 on all the major channels. Now I am receiving 72 to 79 and then it will pick up again. The strangest day had the signal bouncing immediately 72-85-93 - weird! I have no trees in the immediate vicinity, or other encumberances or structures between my antenna & the signal - at least none that I am aware of.

I was thinking of changing my cabling out to the ultra-shielded cabling, but other than that I am stumped. Any thoughts on this one - thanks!
 
Depending on what your current cable is and how old it is, that might help. Could be moisture in a coax connector also.

However, it most likely is "new" interference. This could be anything from trees leafing-out (anywhere on the LOS between your antenna and the source) to electrical/electronic interference. I have a similar problem with one channel. I figured out that it was dependent on time-of-day and days of the week. Since, at best, my signal from this station is weak, when whatever it is gets cranked up, I totally lose the signal. Other days, it pops right on at 75%. I'm working on replacing the antenna and experimenting with different pointing directions for it.
 
That seems to be my M.O. as well. Funny you should mention it, I just replaced all of the cabling with quad/4 layer RJ-6. So all new cabling, with extra insulation and of course all new connectors. I am getting NBC around 72 strength. ABC & CBS are 93 - 100. But sometimes NBC will be 93-100. And, like you said, there is no rhyme or reason to the timing. That is what is driving me nuts - I am looking for some consistency.

I currently have my mast and mount at about a 75 degree angle to get the 72 strength signal on NBC. This really concerns me as if a brisk wind occurs, I see the entire mount ripping a substantial chunk of house from the apex of my roof line! I guess I will continue to tempt fate having this precariously hang off the side of my house. This is really annoying me as I don't know what else to do to get this signal. Thanks for your input - let me know if you find the solution.
 
Just got off the phone w/Channel Master and they suggested that pre-amp. He also suggested standoffs for the 300 ohm wire attaching the antenna to the pre-amp. He suggested that this my main issue now. I am going to change out the pre-amp and see if I can't run down all possible glitches. I will also update this thread to report on my results to help anyone else experiencing similar issues. Stay tuned...
 
Sounds like multipath. A rotor would help for better accuracy when pointing under changing conditions. Trees,temperature changes can play havoc.
 
SUCCESS!!!! One of the main issues brought to my attention by Channel Master during my conversation with their technical support (Wayne Massengill - yes, they will call you back!) was the fact that my 300 OHM lead wire coming from my antenna to pre-amp was just dangling from point to point. Wayne, CM's technical support point man, suggested that I use standoffs to keep the 300 OHM wire from touching the mast.

I purchased these from Lowes, ($1.79 for a set of 2), positioned them away from my metal mast and I took the remaining slack and wrapped it around the pre-amp and then secured it with a plastic tie down. Bang! 100 out of 100 on every digital OTA channel!!! I was very happily surprised. No more inconsistencies. Carl B, I hope you read this as it sounds like this may be your problem also. Should this solution waiver, I will report it as well, but for now I am finally having my expectations surpassed and frustration level is WAY DOWN!! Also, I don't have to engage the rotor whatsoever, all channels come in fine with antenna facing due south! Hope this helps!
 
Keep looking you might smarta**! Actually I spoke too soon. I am back to on & off reception again. I am really at a loss. Can anyone explain why last night I am getting 100% on everything and tonight I am back to an erratic signal? Too perplexed for words!!!!!!
 
Gigawatt said:
Keep looking you might smarta**! Actually I spoke too soon. I am back to on & off reception again. I am really at a loss. Can anyone explain why last night I am getting 100% on everything and tonight I am back to an erratic signal? Too perplexed for words!!!!!!
It is called seasonal multipath- could be weather related. Since you have a rotor just adjust the antenna untill you get the strongest signal.
STB is set top box or otherwise known as a HD tuner.
Are you keeping a picture or is it breaking up?
 
I am keeping the picture. What is so annoying is the pixelation or audio interuption that is occurring. I thought I had it licked yesterday. My next step will be to purchase the better pre-amp. When it gets to this type & frequency of interruption, even turning the rotor doesn't help. I am trying to achieve what I had experienced last night - which was uninterrupted programming. It was a bonus that all channels had the optimal signal strength - I thought I had arrived!!

So, you are asserting that I am at the mercy of the twists & turns of the weather cycles?
 
Gigawatt said:
What is so annoying is the pixelation or audio interuption that is occurring.....So, you are asserting that I am at the mercy of the twists & turns of the weather cycles?

Maybe but then again. I don't think the pre-amp is the issue. You have a very good antenna. Distance is an issue. The farther you are from the towers the more directional or narrower the beam must be. http://www.antennasdirect.com/
Look at the 91xg for example very high gain and a narrow beam(very directional). The CM has a gain of 12db while the 91xg is 16.7
Another thing. How long is your cable run? Do you run the antenna through a splitter? What HD tuner are you using? Some times tiltin the antenna up slightly will help with distance.
 
I am about a 50 foot cable run. I am using the 4 quad insulated cable, if that makes a difference. I have found that tilting the antenna does help. My receiver is a Toshiba DST 3000. I am not splitting any signal. It comes directly from the antenna to my receiver. Only one HDTV in the house for now. I am only trying to receive the local HD's.
 
Interesting. I found the tilt tip just by accident! Would you suggest the Yagi in addition to or in lieu of the 8 bay bowtie? Any suggestions on the most high-powered Yagi? After looking at CM's chart, I don't know if Yagi is the answer given the distance factor. The 8 bay seems to have the distance that I need. See reference chart - http://www.channelmaster.com/. Even the tilt factor did not dispell the inconsistencies. I received a better signal - strength wise, but still would have pixelation & audio interruptions.

Does anyone have any experience using the ATF-X300 (A-Tech Fabrication - http://www.atechfabrication.com/products/atfx300_precision_antenna.htm)? This certainly looks like it would do the job!!
 

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