Inconsistent OTA reception

[Gigawatt]

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!

 

[Carl B]

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.

 

[Gigawatt]

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.

 

[oljim]

It may be your amp, the 7XXX is much better for HD

 

[Gigawatt]

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...

 

[Kevinw]

Sounds like multipath. A rotor would help for better accuracy when pointing under changing conditions. Trees,temperature changes can play havoc.

 

[Gigawatt]

A rotor is part of the setup.

 

[ROLLTIDE]

What kind of receiver do you have ?

 

[Gigawatt]

Toshiba DST-3000

 

[Kevinw]

Still sounds like multipath. How far from towers are you? Your STB may have a problem locking signal also.

 

[Gigawatt]

50-55 miles. What is STB?

 

[Gigawatt]

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!

 

[AcuraCL]

Dam, magic reception standoffs, wish I could find some of these ....

 

[Gigawatt]

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!!!!!!

 

[Kevinw]

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?

 

[Gigawatt]

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?

 

[Kevinw]

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.

 

[Gigawatt]

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.

 

[Kevinw]

You are doing nearly all you can,
Read this-
http://www.atechfabrication.com/information/reducing_multipath.htm

 

[Gigawatt]

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!!