OTA HD - I'm stumped!!

[jc_cc_275]

Hi

I have a situation that has me totally stumped. I'm hoping for some expert advice. I'm afraid that at this point, any further action I take is just "shot gunning" it and will eventually make things worst (or my sanity will go and not necessarily in that order).

Here's some background:

+ CM4228 on a 5' mast mounted on the outside (eve of the house). There are some branches as well as a guy wire/cable that supports a nearby utility pole that can be considered in the direct path. It's not significant but I can't tell whether it's a factor or not

+ Dish 811 receiver

+ Experimented with a AP4800 pre-amp (see below)

+ There is a grounding block between the antenna and the receiver

Without the pre-amp, I was getting the following

KCBS ~87% (yellow UHF, 7.9mi)
KNBC ~77% (yellow UHF, 8mi)
KTLA ~71% (yellow UHF 7.9mi)
KABC ~69% (blue UHF, 7.9mi)
KCAL ~66% (yellow UHF, 7.9mi)
KFOX ~78% (violet UHF, 8.1mi)
KVCR ~66% (red UHF, 55.1mi)
KCET ~64% (violet UHF, 8.1mi)

I tried to enhance the KABC signal which when watching fast moving sequences (such as a football game), the picture pixelates and drops quite frequently. When I put the pre-amp in place, I don't see much difference (KCAL goes up to 72% but then KFOX goes down to 74%). With such a high gain amp, I expected some channels would drop as well due to xmod but none of that happened either - Yes I tried powering down the pre-amp and the picture as expected freezes then goes away

So my questions are:
1) Should I try a lower gain amp (i.e. AP4700)
2) How about raising my antenna to try to get out of the way of the obstructions
3) If I want to route the signal to another TV that will require less than a 50' cable run, can I do it without a distribution amp? If one is needed, does it have to be UHF-only (if it exists)? Any recommendation on model(s)

Any inputs would be greatly appreciated...

 

[JamesJ]

you are so close to everything, but I will tell you in my stiuation (I am 30 miles from every tower) the higher I went the better, but that is my situation, have you tired an indoor antenna such as a silver sensor or not? you are so close the one you will lose is kvcr but only 8-9 miles from everything else you should be able to pull them in nice, plus tweeking would be alot easier!

 

[jc_cc_275]

one more thing - the preamp is mounted on the mast itself so it's less than 2' from where the antenna picks off the signal. The power supply for the amp is farther away, inside closer to where the receiver is

 

[KE4EST]

one more thing - the preamp is mounted on the mast itself so it's less than 2' from where the antenna picks off the signal. The power supply for the amp is farther away, inside closer to where the receiver is

Thats the way it is designed to be, that is not your problem(unless u have something hooked up wrong).

 

[jc_cc_275]

hi stuart628

I tried both an indoor antenna (it was a Philips model that had a built-in VHF/UHF amp - I had to turn the VHF down and turn the UHF up to max) as well as attic mounting the 4228... The signal strength is about the same, maybe a bit weaker but the main drawback was I couldn't get all the signals at the same time... That's how I ultimately ended up with mounting it outside...

 

[TheDishNetworkInstaller]

Sounds like you need to go higher or move the antenna to get around or over your mentioned possible obstructions.

 

[Hall]

At your distance, the branches and a guy-wire should be non-issues. OTA reception is not like satellite where there's a focal point that you have to aim exactly at.

Have you rotated the antenna around a bit to see if things change ?

 

[NOHDjunkie]

Try a Zenith Silver Sensor. Best $20 I ever spent.

 

[rickc]

When I first got my HDTV I tried darn near all the latest and greatest indoor antennas, with varying success. I then bought a radio shack medium range combination UHF/VHF antenna (I'm less than 12 miles away from the antenna farm, but have some big-time obstacles in the path) up into my attic. Slight improvement.
Then I gave up and moved it to the roof. Wow! What a difference. As mentioned above, higher may well be your answer.
Since two of our local DTV stations are VHF, I needed the UHF/VHF unit, if your stations are all UHF you can get by with a UHF only antenna.

 

[jergenf]

If you're using a 28db preamp it could be overloading the signal although the signal numbers you quoted don't show that. You would have to look at analog channels to determine things like overload and ghosts. If it is overloading then
try a 19db preamp.

Moving the antenna may help because UHF has sweet and dead spots. Try adjusting the antenna while manually during the signal menu. An 8 bay antenna is the most directional you can get.

If your receiver has a UHF remote and you have a handheld TV run a temporary coax from the channel 3 output to the TV and use the remote to select the menus. Else you'll need someone to assist.

 

[boba]

Forget the amplifier at that distance from the broadcast towers you have a much better chance of multipath interference. Your problem may be too much signal rather than too little. At that distance from the towers the signal is very strong and can bounce off objects giving many paths to your antenna. Sometimes pointing away from the tower can give the best signal, it will be trial and error. Try choosing 1 channel and slowly rotate the antenna 360 degrees to find the strongest signal then try other channels to see how their signal comes in.

 

[DVDDAD]

Height cures most evils, go higher and your problems might go away!

 

[TLaz]

Ota Hdtv

I live approx 16 miles from my local HDTV transmitters. I found that if I added an amplifier to improve reception on a low powered station, that the signal from the other strong stations would actually diminish. I believe it has something to do with overloading the HDTV tuner.

 

[RandallA]

I have an indoor amplified Terk antenna (I know, I know) for my OTA HD channels. It works for me except for ABC here in the Bay Area. I get pixelation in video and audio just keep dropping, simply put just garbage. The other stations are just great.

I gave up, I just couldn't get it to work with the 811. The signal is in the mid 70s and one time I got it to mid 80s but it will keep doing it. Contacted the station but didn't hear anything from them.

Also, the amp. has to be all the way down to zero. If I raise it just a notch, I overload the HDTV tuner and don't get anything. I'm very close to the towers 1.9 and 6.3 miles. That's probably why the Terk antenna works.

 

[BrettTRay]

Get a adjustable attenuator from Radio Shack. If you do away with the preamp you will probably have problems with the station that is 55 miles away. 28db is alot for being only 7-10 miles from the transmitters. also, do u have a metal roof. Lots of times people with metal roofs have a lot of problems with reflections. I am 60-90 miles from the stations that I pick up and trust me very few people have went to the extremes that I have went to to get reliable reception. I put up a 60' rohn tower, rotor, and have had lots of exotic and professional antennas (Wade Parabolics/Sitco yagis/Scala Paraflector/ETC.), preamps, QS RG11, and the whole nine yards. I wish I could be more help but I really don't have much experience with picking up stations at that close of a distance. One thing thing is if the guy wire is pretty close to the antenna and is in direct line of site you can bet that it hinders the reception. What kind of 300/75ohm transformer are you using. Lots of people including me have had much better signal strength when using a channel master transformer (#0090) compared to others like radio shack and some of the others.

 

[jc_cc_275]

Thanks for all your inputs...

Here's my plan

+ I will get another 5' extension and elevate the antenna

+ The multipath interference theory sounds interesting - I will try the experiment of aiming away from the tower

As for the indoor amp, I'm going to put that on the back-burner. An indoor antenna is what I started with and it was just a very "clumsy" solution:

+ Putting it near a window made a big difference which in my case which wasn't always very convienient

+ I couldn't get all the channels (similar to RandallA). Since all my HD signals are UHF, in my case I had to turn the UHF gain all the way up and the VHF gain all the way down

Of course, I will report back on the results of my experiments.

 

[jc_cc_275]

BrettTRay

My roof is tile...

As for the transformer, if I understand correctly, you are talking about the transformer for the antenna? - I'm just using the outdoor balun/matching transformer that came with the 4228...

 

[BrettTRay]

yea the balun/transformer that came with the antenna is a good one if not one of the best. People wouldn't beleive the difference that little thing can make if you have one of the Channel Master ones compared to the cheap models.

 

[iKramerica]

where are you in LA? Have you tried the $50 radio shack indoor antenna with built in variable amplifier? It really works for me in the valley, and is very adjustable. If it doesn't work for you, you can return it.

 

[Tower Guy]

Hi
I have a situation that has me totally stumped. Any inputs would be greatly appreciated...

The preamp is overloaded, remove it. There's no need to replace it with a lower gain amplifier.

The stations on Mt. Wilson are above the narrow beam of the 4228, try aiming it up 12 degrees.