Antenna power question?

[captain_caveman]

Bear with me on this… I recently set up an antenna away from my house for the only local channel that we can receive around here. I'm going to put all pertinent information to see if anyone can help me figure this out. I'm using a Stellar Labs 30-2476 pointed around 100 degrees off azimuth toward a hill to catch the bounce down in a valley (direct signal blocked by hills) for a transmitter about 20 miles away, but with double diffraction. I tested with a 25' coax cable at the pole and had good signal, but the small tv didn't have a signal meter. Now to the technical part and my question.

I'm hooking this to a Dish Network system with a diplexer on the incoming side and a signal separator on the receiver side. The calculated loss of everything from the antenna to the TV is about 24 dB including the coax, ground block, diplexer, signal separator, and splitter. I tried with an unamplified setup, and was met with no signal in the house, so I used a CM-7777 Titan2 preamp that I had from a previous install, and expected a modest 6 dB or so gain, was met with all kinds of issues inside that turned out to be over-power. I used what I had on hand, which was coax splitters, and wound up having to use a couple coax cables, a 4-way splitter with the input cable ran into an output port, and the output cable on another output port, and a 3-way splitter in the regular way with output on a 7 dB output port for over 21 dB of attenuation before I could get a stable signal.

Why would this not work with an unamplified system? If I had to take off another 21 dB of signal after the run, then it seems that the signal from the antenna should have been strong enough to push through to the tv, and/or why would I have to attenuate so much with the Titan2? It only boosts around 30 db, but I have a total of about 45 dB loss including the attenuation.

 

[navychop]

Which Dish STB are you using?

 

[captain_caveman]

Which Dish STB are you using?

Sorry, I'm using a 722k. I'm not really using its tuner though. I'm more concerned with getting a clean signal through to my TV.

 

[Triride44]

Try a pre-amp with adjustable gain at the antenna.

 

[captain_caveman]

Try a pre-amp with adjustable gain at the antenna.

That's my ultimate plan, I was just wondering why I need so much attenuation after my components used up nearly all the boost from the Channel Master.

 

[primestar31]

I was just wondering why I need so much attenuation after my components used up nearly all the boost from the Channel Master.

Maybe your calculated dB loss figure is wrong. That Stellar Labs antenna is HIGH VHF only, and amping VHF is not something that should normally be done. Because it also amplifies noise, which VHF is very susceptible to. That Channel Master preamp is way overkill for just about everybody.

I would suggest that you run the coax from the antenna to your house, and directly into a tv set there, not through any splitters, preamps, or anything else, and see what kind of signal you get. Then figure out how to add the other stuff one at a time to track down which one is killing your signal.

 

[captain_caveman]

Maybe your calculated dB loss figure is wrong. That Stellar Labs antenna is HIGH VHF only, and amping VHF is not something that should normally be done. Because it also amplifies noise, which VHF is very susceptible to. That Channel Master preamp is way overkill for just about everybody.

I would suggest that you run the coax from the antenna to your house, and directly into a tv set there, not through any splitters, preamps, or anything else, and see what kind of signal you get. Then figure out how to add the other stuff one at a time to track down which one is killing your signal.

You know what, when I calculated my loss I used the average loss per foot of RG-6, so I went back out and counted and measured every component and recalculated for channel 12 vhf. It turns out I only had about 16-17 dB loss. That would put me 13-14 dB over on the boost from the preamp. So, whatever the signal strength was plus (let's say) 14 dB. That's getting into pretty high territory. I still can't reconcile (in my mind) having to shed 21 to get to good usable signal though when it worked at the pole.

As far as running the cable straight to my house, I don't have that much coax laying around. Part of the reason I chose this spot for my antenna was that I already had coax running to both my TVs. I did however check the signal with the 50' piece of RG-6 that runs from my preamp to the power inserter hooked directly to the antenna with a coupler and a 100' spool of RG-6, and although I got a signal lock, it was pretty pixelated.

I'm OK with what I've actually got set up. I have some attenuators ordered for the cable at each tv, and I can make do with the splitter/attenuator setup until then.