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Discussion Starter · #1 ·
Have CM4221 installed in attic (austin, texas), receiving all OTA local HDTV broadcasts. This is feeding my OTA tuner module in my dish 6000 receiver.


some stations come in 80-90 signal strengths, but others are in the 60-70's with dropouts and other such issues.


So I added the CM 7777 pre-amp to this setup. Pre-amp module on mast, power module about 6 feet away, also in the attic. RG6 throughout. Currently have UHF/VHF switch setting to seperate but do not have a 75 OHM terminator installed in the VHF input.


After adding the 7777 i have zero improvement, everything is exactly as it was before (zero increase in signal strength, etc). Do I need the 75 OHM terminator? Should i forget the terminator and switch back to the combined switch setting?


Also, the manual specifies that the power module should be placed as close to the tv (or tuner) as possible. it's easier for me to keep it in the attic, but i can move it to where the tv is if that would improve things. I would estimate that currently the tv/tuner is approx 40ft from 7777 power module.


please let me know your thoughts....
 

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I bought a 4 way rca splitter/amp with this antenna from Home Depot and went from a 55% on Fox to 89- 100% on Fox. What STB are you using?
 

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Quote:
Originally posted by mikeinaustin
Should i forget the terminator and switch back to the combined switch setting?


Also, the manual specifies that the power module should be placed as close to the tv (or tuner) as possible. it's easier for me to keep it in the attic, but i can move it to where the tv is if that would improve things. I would estimate that currently the tv/tuner is approx 40ft from 7777 power module.


please let me know your thoughts....
The separate switch setting work much better for me. I have my power module close to my tv distribution system. It works great. Greywolf is right. Put it close to your tv.


Gary
 

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I also added the CM 7777 and got zero improvement. What a surprise and waste of money. Using a 8200 Winegard and RG6 cable.
 

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Quote:
Originally posted by jldet5
I also added the CM 7777 and got zero improvement. What a surprise and waste of money. Using a 8200 Winegard and RG6 cable.
Pre-amps are designed to boost a signal for long cable runs. They are not designed to create the signal where there is none.

You need a more sensitive antenna, higher pole, or both.


Kirill
 

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Kirill,


When you say, preamps boost a signal. Do you mean that if you are getting a signal of 70s to 90s, that maybe the preamp would boost it to say 100?


I understand that it wouldn't create a signal if you are getting 0 to 20, but I would assume that if you are getting over 70 that it could be perfected??


Or do you need a bigger or higher antenna like you said?
 

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Quote:
Originally posted by jldet5
I also added the CM 7777 and got zero improvement. What a surprise and waste of money. Using a 8200 Winegard and RG6 cable.
Well it certaintly made a difference in my case. I had a signal in the 30's before on WCBS-DT (about 40 miles away) and could rarely lock it for more than a few seconds. Now the signal is in the high 60's and rarely drops out. I'm also pulling in some closer stations without even having to rotate the antenna. (using the $20 Radio Shack outdoor UHF yagi)
 

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Quote:
Originally posted by pipman2k
Kirill,


When you say, preamps boost a signal. Do you mean that if you are getting a signal of 70s to 90s, that maybe the preamp would boost it to say 100?


I understand that it wouldn't create a signal if you are getting 0 to 20, but I would assume that if you are getting over 70 that it could be perfected??


Or do you need a bigger or higher antenna like you said?
Digital signal meters do not show the absolute level of the signal. To put it simple, they show the "usability" of it. Pre-amps boost the absolute level of the signal. So if you loose, let's say, 10dB on your long cable run, pre-amp would be able to recoup it.

On the other hand, if your meter shows 70 because your antenna does not get enough signal (too small, too low, multipath), pre-amp will not help.


Kirill
 

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Discussion Starter · #11 ·
update:


installed 75ohm terminator on unused vhf input of 7777, this made no difference.


next, moved power module from attic to right next to the tv/tuner module, this made no difference.


the channel master 4228 is the only uhf antenna that i've heard is more sensitive than the channel master 4221, but there is no easy way of getting that into my attic.


local rules do not allow antennas outside of house, so it must remain in my attic. i relocated the 4221 to the absolute peak of my attic, which is actually fairly high up, and this also made zero difference.


i would guess i am about 7-9 miles from the transmitters here in austin (they are basically all located in the same area). i am not in any type of valley or low spot in austin.


i do not believe i should be having this much trouble getting a good signal (other than for the local fox station which is just puttering around with their stuff) with the equipment i am using.
 

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While for DBS satellite signals, the "signal strength" meter really does measure signal strength, for OTA, that's not necessarily true. When receiving a satellite signal, low signal level is just about the only impairment, so a low metter reading indicates a weal signal.


Not so with OTA. Other things can also cause a low mter reading reading. The meter is an indication of signal "quality", and, for example, excessive multipath, beyond the receiver's capability to cancel, will also cause a low reading.


If a weak signal is not the cause of a low meter reading, then adding a preamp will make no difference.


BTW, despite what others have said, I see no technical reason why the location of the power module would make a difference. It's just a power injector, and should be able to be put anywhere between the TV and the preamp. Still, since it generates a bit of heat it would probably be better for it to stay out of a hot Texas attic.
 

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mikeinaustin;

If you are 7 -> 9 miles from the transmitters the last thing you need is a pre-amp. Look elsewhere for your problem. Try the roof temporarilly as an experiment and lose the pre-amp. A carefully aimed 4228 might help if multipath is your trouble.


I agree with BarryO also. I can think of no reason what difference the location of the power module makes as long as it is somewhere between the amp and the receiver.
 

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Mike


Local governments and housing associations can not stop you mounting an antenna to your roof look elsewhere on this forum it has been well discussed. I thought the same but was pleasantly surprised.

http://www.fcc.gov/mb/facts/otard.html


You can prove you tried an internal install so you are well set. Now you just have to get the better half to approve, that might be tougher!


Andrew
 

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Mike, being that you are only 7-9 miles away from the antenna farm, are you in the hills? You may be getting some mulit-path interference. What channels are giving you trouble?


I don't think the pre-amp will help out, I tried a CM 7778 where I live up in Georgetown, but it didn't increase my digital signal strength at all, it just added some noise to the picture on the analogs.
 

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If you're only 7-9 miles from the antenna farm, a preamp will not help. Preamps work best when you're away from all signals.


Agree with the other posters your options are:


1) move the antenna around in the attic to find a better location.


2) get a more directional antenna


3) move the antenna outdoors (local rules prohibiting such antennas are illegal so says the FCC).


good luck!
 

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If everyone keeps saying that the HD/Satellite receivers don't give good readings on antenna signal strength, then how else do you find out if you are getting a perfect signal?
 

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I live in Houston about 20 miles away from the transmitters. I was experiencing a low signal strength. Then I removed all dipixlers and splitters and made a dedicated cable run from the antenna to the OTA receiver. Since I did this, I have had 100% signal strength on every Houston HD Channel, and I even receive CBS out of Bryan/College Station. I have Hughes E86 and a RS 120" outdoor antenna.


Hope this helps,
 

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Discussion Starter · #20 ·
for whatever reason, where i live in north austin i get some extremely strong winds each summer. one of my trees was lifted out of the ground last summer (i actually put it back in with my fathers help and its been fine since).


i have one friend who put an antenna up (he lives in another neighboorhood) and he made absolutely sure it could not be blown down. however, it was blown down, taking a large chunk of his house with it! i guess the wood gave before the metal did.


i am already at the absolute peak in the attic. i can try and relocate to another area where there is perhaps less obstructions between the antenna and the transmitters, but the antenna will be at least 10 feet lower in any other location.
 
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