new to forum but want to ask this

smcrae43 · 17-Jan-2011, 5:55 PM

Own a mobile with a metal skirt. Ran 50 feet of coax to an Outdoor "flying saucer" style UHF antenna (has 30dbi amp also) So its a pretty strong system which only provided 2 channels out of the gate. Have a 1 year old flat screen. All our reachable stations are from the same repeater location at 270 degrees south of me and 32 miles away. Some digital and some are not yet converted I guess. I unhooked the coax in trying a different antenna which didn't work. I re-hooked up the coax again to the same flying saucer a second time and now have 6 channels?. More to obtain yet!!!!

Not sure what I did different. The connections are tight but is my house causing more interferences that I first thought? Curiously we were in a storm when the other channels came in - that's weird. The saucer is sitting 2 feet above a metal roof but shouldn't that have affected things from the beginning?

thanks for any thoughts or suggestions to try out.....
Sam

mtownsend · 18-Jan-2011, 5:40 PM

Could you please post a link to a tvfool analysis for your exact location? That will help us figure out what stations are within range of your location.

The amplified saucer antenna has a built-in amp, so it needs a power supply to drive the internal electronics. Do you have the power supply hooked up (and correctly)?

Are there any splitters between the power injector and the antenna? If you do, you might be sending power to places you don't intend to, and it might also result in insufficient power being delivered to the amp in the antenna.

smcrae43 · 18-Jan-2011, 5:53 PM

http://www.tvfool.com/?option=com_wr...3cf465fa08387d

Here is the TV Fool info. I think I'm switching to a High Gain UHF rake style antenna, plus quad shielded coax and a nice adapter at the antenna itself. I just need to raise it high enough to matter. I have this model - Antennacraft® MXU47 UHF Antenna. It has a 80" main boom and has 10db gain with 16 front to back. I need another one to replace the flying saucer though. The saucer is working okay but I have allot of metallic interferences all around my location.

thanks for your continued feedback.
Sam

smcrae43 · 18-Jan-2011, 7:07 PM

Didn't see the last reply I sent so I'll try again.

I'm switching to a Antennacraft® MXU47 UHF Antenna, has a 80" main boom and has 10db gain with 16 front to back. Going to buy quad shielded coax and a decent pig tail adapter. Lots-O-metal around my house being a mobile home.

Here is the TV Fool info

http://www.tvfool.com/?option=com_wr...3cf465fa08387d

thanks

mtownsend · 18-Jan-2011, 7:31 PM

The good news is that all your local stations are coming from the same direction. You just need to point your antenna at compass heading 148º.

BTW, the MXU47 is a UHF-only antenna (channels 14-69). The high gain and tight antenna pattern for this antenna will surely perform better than your saucer antenna.

Please note that this antenna is not designed to pick up VHF channels (channels 2-13). K05KX (translator for KWVT) appears to be the only VHF channel in your neighborhood, and it's pretty strong, so there's a chance that you might get enough signal through your antenna to make it still watchable. If not, then you may need to add a VHF antenna or switch to a VHF/UHF combo antenna.

smcrae43 · 18-Jan-2011, 8:03 PM

If I get above my roof line by 10 feet or so, do I need to worry about my neighbor house - also metal???

mtownsend · 18-Jan-2011, 8:19 PM

Any objects that can reflect signals (including your neighbor's house) can potentially add multipath to your signal, and this can make it more difficult for your receiver to lock on to a channel.

However, if you go with a directional antenna like the MXU47, the chances of severe multipath are greatly reduced. There's no way to know for certain how much of a problem you have until you try it, but my initial feeling is that you should be fine.

You can also use your analog channels as a guide for seeing how much multipath you might be dealing with. If you see "ghosts" or "double-images" on your analog stations, then it's a clear sign that multipath is affecting those channels. If the ghosts are very strong and clearly visible, then it means the multipath echoes are pretty strong.

Sometimes it's possible to re-point the antenna or move it to a different part of the roof to a spot that has less multipath. In any case, a directional antenna is a nice step in the right direction. I'd start with that, and consider additional steps if you find out there are problems.

smcrae43 · 18-Jan-2011, 8:59 PM

So if I get better height up a pole or mast, but have to increase the length of coax to 100 feet, then will I need an amp with the UHF antenna or do you think I should try it like that without it??

thanks

John Candle · 18-Jan-2011, 10:33 PM

The MXU 47 is a highly directional antenna and that is good for reduction / elemination of multipath. Start with the antenna down lower then 10 feet above the roof of the mobile home , no need to do monkey swinging antics if the reception is Ok. You should have enough signal strength for 1 or 2 tv's with out a amplifier.

smcrae43 · 19-Jan-2011, 12:29 PM

Yeah I got the antenna up and is now about 2 feet, right above the very peak of my roof. It is regular tab roofing on that part and is also the highest point on my property that I could mount something right away and try. I did get allot of snow on-screen (marching ants as my daughter puts it), when I faced south of my location and gently swinging south to south-east and south to south-west (very slowly back and fourth) yielded only slight changes in quality but none worth writing about - even though I guess I am..... after many failed tries and before conceding for the night, I swung the antenna clear around to a northerly direction. We have a second more distant repeater station facing that direction. I was able to pick up 1 digital channel pretty clear (CBS) and a second analog channel not so clear (KPTV Fox 12). So at least I know I have decent connection continuity with the setup I did. So tonight I will have to try something else.

So do I need to worry about elevation as well. In other words do I need to point the boom of the antenna higher into the sky maybe...

thanks again

mtownsend · 19-Jan-2011, 4:17 PM

Can you tell what real channel numbers are you picking up (analog and digital)? For you digital channel, can you get your receiver to tell you the real channel number? With so many repeaters around, it would be nice to know which signals you are really picking up.

The transmitters to your north are predicted to be much weaker than the signals from the south (because terrain is blocking the northern transmitters). It makes me wonder if you were picking up a signal bouncing off the hills when you pointed your antenna north. The transmitters to the south should be line-of-sight (hence the LOS path indicator). Are there any trees or other buildings blocking your antenna's view to the south?

BTW, as a general rule of thumb, it's best to keep the antenna at least a few feet away from any other objects (like your metal roof). Anything conductive near the antenna can change its electrical characteristics. I usually recommend putting the antenna at least about 4-5 feet above the roof to reduce the influence that the roof has on the antenna's performance.

Quote:

So if I get better height up a pole or mast, but have to increase the length of coax to 100 feet, then will I need an amp with the UHF antenna or do you think I should try it like that without it?

How long is the cable run now?

For lengthy cable runs, a pre-amp can help. Yes, you can try it without the amp first and add it later if needed.

smcrae43 · 19-Jan-2011, 4:30 PM

Yeah I have 100 feet of cable at this antenna. The part under the house is quad shielded. The antenna is, I think, not high enough. It's sitting on a little stand which is lag-bolted to the face of the roof-eve. I'm about certain a pole mast system is in order. Yes there is one old metallic single-wide to my south. I will raise things up further and point south again to try.

thank you
Sam

John Candle · 19-Jan-2011, 10:37 PM

Always check all connections , look inside the connectors on the ends of the coax. What you are looking for is , see if the foil shield and shield wires are pushed in toward the center conductor , push the foil shield and shield wires away from the center conductor. Never assume that coax is good. Is there a splice in the coax under the trailer?? Has water and corrosion entered in the coax or coax connections any where?? Has the dog chewed on the coax?? Is the matching transformer at the antenna bad?? The Tv transmitters to south east are showing LOS = Line Of Sight to the south east. Connect the antenna DIRECTLY to the Tv or converter box with known to be good coax and known to be good matching transformer.

GroundUrMast · 19-Jan-2011, 10:57 PM

I'm with you on this one John. Sounds like there is more than one piece of coax in this run. That makes me 10 times as suspicious of any one of the items you mentioned.

smcrae43 · 20-Jan-2011, 12:42 PM

Thank you guys for the input. I will check out all the connections. Yes there is 100 feet (two sections of 50 foot coax). The section attached at the antenna is about a week old but is Radio Shack "antenna coax" so they call it at their store. The other is quad shielded (GE brand that I could find here locally but at a different store) and is about two days old that runs under the house and up to the TV. I used one of those little threaded barrel connectors to allow both lengths to screw together in the middle.

The only place I question is at the base of the antenna where that pig tail adapter is screwed onto the threaded poles. The thing is a cheaper Radio Shack brand and I would call it an indoor version of these - vuh/uhf/fm transformer that I really have a bad feeling about. Not sure why but I do. I'm thinking about getting a nicer one from Channelmaster or somewhere else.

The other thing I did is bought a 20 foot length of galvanized 1 1/2" pole. If I cement that into the ground and bolt-clamp it to my eve face, it'll set me about 12-15 feet above the peak of my roof after it's raised. Right now I'm just a couple feet above the roof-peak. It'll be a bit daunting doing it on my own but if the Egyptians can build pyramids I should be able to raise a 20 foot mast by myself. I have some ideas how.

Thanks again for the suggestions - I'll check them out!!

smcrae43 · 20-Jan-2011, 8:16 PM

I want to thank everyone for their great input. I will send out a few pics of the final project for all to see.

thanks again

Sam

John Candle · 20-Jan-2011, 11:51 PM

You can use a low gain preamp like the the Winegard AP8700 it bosts the signal in both the vhf and uhf. Also about the repeater/translator Analog stations they are duplicates of the Digital Transmitters and might not be on the air. The whole point of going digital is better pictures and sound and more channels. And switch off the Analogs that transmit one channel.

smcrae43 · 21-Jan-2011, 1:11 PM

Yeah I have a 30db amp at one TV - its helping that saucer antenna at the moment.

My ultimate plan is to raise up my Antennacraft® MXU47 to 20 feet above ground and split off so both TVs I have are serviced by it. Radio Shack will be getting their saucer back. There I can see the amp really helping.

One thing I keep forgetting to ask is do they make filters for 110v for filtering away electrical current. Our signal reception is affected by other appliances when they run - the picture garbles when the microwave is running.

I'm looking to re-route the power just for the TV and the pre-amp. thanks for any ideas.

Sam

John Candle · 21-Jan-2011, 3:28 PM

A microwave oven will not cause interference unless it is defective. What about the washer and dryer do they cause interference? Unplug every thing in , on , around the house , unplug every thing out side of the house , unplug the electric fence charger , every thing means every thing , except the Tv. Connect the MXU 47 antenna DIRECT to the Tv , no splitters no amps , DIRECT to the Tv. Is there interference with the Tv now? If the answer is no , then plug things back in and turn them on One At A Time.