Frustrating OTA Reception Issues

buddylee375

DTVUSA Jr. Member
#1
Hello,

For a couple of years now, I've had an old hand-me-down antenna installed in the attic of my 2-story house. I couldn't even tell you what the brand name of it was, but it was a fairly decent sized antenna and that's about all I know about it. The cable for the antenna ran from the attic to the basement, where it split into two which then ran to different rooms on the first floor. I had ok reception with that, about 60-70% of the local channels came in consistently, sometimes more or less depending on the time and weather, but really I could get just as good reception with some bunny ears I had on a TV in a bedroom on the second floor.

When I bought a new TV for the bedroom in the second floor, there wasn't much room for the bunny ears anymore so I decided to hook up the antenna in the attic to this TV also. I used a splitter in the attic to split the cable so one ran into the bedroom below it and the other ran into the basement where it was then split again. I figured the reception would be the same on both TV's but it definitely was not, which I figure is due mostly to the two different brands of TV's (lower level is a Sony Bravia, upstairs is a Samsung).

I thought I would upgrade to a better antenna and after reading a few reviews and comments I bought an RCA ANT751R as well as a Channel Master CM 7777 Preamplifier to go with it. The new antenna was about half the size as the previous one, but I thought it would still work better... maybe not. After installing the new antenna and the amp, re-scanning for channels, I now have worse reception than I did before.

I have the antenna pointed NE as that's where most of the channels I watch are broadcasted from. I think all the coax cable I'm using is RG6. My brother in-law helped me install the first antenna and had a box of cable he got from a friend who installed tv's, but it looks like it's the right thickness.

I'm not sure what I've done right/wrong, if I have too many splitters (one of the splitters isn't being used a splitter as more of a connector, one cable in, one cable out). If there is any advice someone may have, it would most definitely be appreciated.

Here is a link to the TV Fool analysis

Thanks!
 

dkreichen1968

Moderator
Staff member
#2
How are you injecting the power for the preamp? For it to work correctly the power needs to be injected between the antenna and any splitters. An unpowered amp will attenuate your signal rather than boost it, and DC power going to your TV tuner could damage it.

Splitters will aways split the signal in two (3.5 dB loss) whether its hooked to a TV or not. So your upstairs TV is seeing twice the signal strength level as your downstairs TV.

Depending on the materials that your roof and siding are made out of your losing about 50% of the available signal by having your antenna attic mounted. If it's a possiblity I'd think about moving the antenna outdoors. Looking at your predicted signal strengths on TVfool I doubt you actually need an amp for two TVs (even attic mounted), and with a little work I see no reason why you shouldn't be getting 100% reliable reception.

Your old antenna may have been a higher gain antenna than the RCA ANT751R and depending on condition may have been an overall better antenna. I can't tell you for sure without seeing it.
 

buddylee375

DTVUSA Jr. Member
#3
Hey thanks for the reply. I have the preamp connected to the antenna directly, then the power output on the preamp is connected to the 3-directional power inserter that came with it. The first splitter is connected to the output labeled "to TV" on the power inserter.

Even though my upstairs TV should be receiving twice the strength, my downstairs TV still picks up some stations better, is this due to the different brands of the TV's and the difference in tuners?

The second story and attic are covered in cedar shingles, but I couldn't tell you if there was anything else behind them, it's an older 1920 sears kit home. As for the roof, there are asphalt shingles on currently, but again I'm not completely sure if they installed those over something else.

I'll run out tomorrow and get the right connections to reduce the amount of splits I have in the lines right now and see if that makes any difference. I guess it's possible the cable I'm using may also be part of the issue. I still have the old antenna, so I may try hooking that back up with the preamp and seeing what happens.

Thanks again.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#4
I'm not sure what I've done right/wrong, if I have too many splitters (one of the splitters isn't being used a splitter as more of a connector, one cable in, one cable out). If there is any advice someone may have, it would most definitely be appreciated.

Here is a link to the TV Fool analysis

Thanks!
:welcome: Buddylee375,

By using a splitter as a method to connect two coaxial cables together, you are cutting the signal level in half on that circuit. You can buy a 'double-female' connector at your local Radio Shack for a couple dollars that will restore that lost signal.

Jim

 
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buddylee375

DTVUSA Jr. Member
#5
Alright so time for a little update. I had some time to play around with it some more today and test a couple things out.

First thing I did was removed all the unnecessary splits and replacing them with the connectors shown above (thanks for that!) and a 2-1 splitter instead of a 3-1 splitter. After doing that, I checked the reception still with the RCA antenna and preamp installed. The results yielded a little better reception, but still nowhere what I think I should be getting. Not all of the channels came in, and the ones that did still had some interference from time to time. It seems like even though the Sony downstairs has one more split in the cable, it still picks up the channels better than the Samsung upstairs.

Next thing I tried was changing out the antenna I just bought with the older one I had replaced (pictured below) as it had been suggested that this could possibly be a better antenna anyway. Still connected to the preamp, I checked my results again and they if anything, they were worse than with the RCA antenna.

I then individually connected the TV's one by one to the antenna/amp combo to see if it that was possibly affecting it, and still had poor results.

My best results came from of all things, removing the preamp entirely and using almost the same setup I had before I even bought the new items, just with the cleaned up cable lines. On the Sony downstairs, I am getting all but one channel and on the Samsung upstairs, I am only getting maybe 60% of the channels. If it helps at all, I could get into more detail as far as which channels on which TV do or do not come in when connected in a certain configuration.

Again, thanks for any advice you may have.

Picture of older antenna: antennaold.jpg

-Joe
 

dkreichen1968

Moderator
Staff member
#6
It appears the old antenna is a better antenna than the RCA. Bigger (more elements) generally equals a better antenna. I'm thinking there may be something wrong with the cabling going to the upstairs TV. Are the connections factory or homemade? The amp may be overloading your system. What channels are you getting where?
 

buddylee375

DTVUSA Jr. Member
#8
It appears the old antenna is a better antenna than the RCA. Bigger (more elements) generally equals a better antenna. I'm thinking there may be something wrong with the cabling going to the upstairs TV. Are the connections factory or homemade? The amp may be overloading your system. What channels are you getting where?
That's good information to know about the antenna. Most of the connection cables have been cut from a larger length of cable when we first installed the antenna a couple years ago. The actual connectors are mostly rg6 twist-on or crimp connectors added to the ends of that cable. Should I replace the cabling with some that I know is the proper is type and has factory connectors already in place?

The downstairs TV is able to pick up 2.1, 5.1, 11.1, 26.1, 32.1, 38.1 and the subchannels on a few of them, all pretty reliably right now. It is having a hard time getting channel 14.1.
The upstairs TV is only able to pick up 2.1 and its subchannels, 5.1 pretty patchy though, and just a tiny bit of 32.1. Nothing else comes up on the channel auto scan.


If you don't mind my asking, what's a 3-directional power inserter and do you mean it came with your CM7777 preamp?
I probably didn't use the correct term, but yes, it did come with the preamp. Here's a pic of it.

CM-7777-6T.jpg

Thanks,

Joe
 
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Tim58hsv

DTVUSA Member
#9
OK, thanks.

That power inserter doesn't normally come with the CM7777 preamp and I'm not sure it can be used with one. Someone here will know but yea, that could be part of the problem you're having with reception.
 

dkreichen1968

Moderator
Staff member
#10
OK, thanks.

That power inserter doesn't normally come with the CM7777 preamp and I'm not sure it can be used with one. Someone here will know but yea, that could be part of the problem you're having with reception.
I see no reason why it wouldn't work as long as the power supply is of the correct voltage. It simply passes DC to the amp while passing the RF to the TVs.
 

dkreichen1968

Moderator
Staff member
#11
The actual connectors are mostly rg6 twist-on or crimp connectors added to the ends of that cable. Should I replace the cabling with some that I know is the proper is type and has factory connectors already in place?
Yes, or get a good compression F connector tool and connectors and replace all the twist on or crimp connectors. Shorted out connections could explain your problems. I'll almost guarantee that there is something wrong with the cable going to your upstairs TV and channel 14.1 should be no problem on either TVs. I helped one of my coworkers with her antenna system and her problems were simply shorted out homemade cables, so it certainly can be a problem.
 

nbound-au

The Graveyard Shift
#12
Nothing wrong with hex crimp connectors, as long as they were done correctly. (No shorting, centre pin reasonable length, crimped with proper tool - not pliers)
 

buddylee375

DTVUSA Jr. Member
#13
Nothing wrong with hex crimp connectors, as long as they were done correctly. (No shorting, centre pin reasonable length, crimped with proper tool - not pliers)
I'm afraid I can't confirm they were all done correctly... I'll get some decent cables and replace the ones that probably should be. I'll give an update on the reception after everything's been changed out.
 
#14
My best results came from of all things, removing the preamp entirely -Joe
The 7777 preamp is overloaded. Try the 751 by itself, and then try moving the antenna to other locations in the attic and re-aim until the reception improves on a single TV set. Then add splitters until all sets are working. If you loose anything by adding splitters consider a CM 3414 distribution amplifier.
 

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