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Discussion Starter · #1 ·
I've already got a channel master 7775 in-line pre-amp on my antenna. I can get fairly good signal strength, but it's not entirely stable and could be better. Is is conceivable that a second amp, inserted between the cm preamp box in the house and the receiver could boost the signal strength even more?
 

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Be very careful here - it is possible to amplify TOO MUCH and cause more problems than you started with. But yes, you can. Just keep the power-supply/amp together.


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You CAN put antennas on your owned and/or controlled property...

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

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You will "probably" find that the first amp will just overload the second amp with no improvement in performance. A preamp amplifies everything: the desired signal, undesired signals and noise.


Sometimes you can get away with adding an amplified spitter if all you're using it for is maintaining unity gain to overcome losses in multiple cables and connectors feeding multiple receivers, but you still have to be careful that it's not being overloaded by the original antenna-mounted preamp.


Sometimes the antenna-mounted preamp itself may be overloaded by a strong signal, and this can degrade receiver performance.


Randy, can you describe which signal you're having trouble with along with the nature of analog and/or digital signals on nearby channels, their broadcast power levels and distances from you, etc.? I'm wondering whether you may be boosting an already strong analog or digital signal on a near or adjacent channel, possibly causing interference to the signal that you're interested in. If this is the case, you may need to employ a trap filter of some kind. (You wouldn't believe the "plumbing" of amps, traps and connectors I had to resort to to get a distant DTV on channel 9 without interference from a very strong analog signal on channel 12. http://www.avsforum.com/ubb/wink.gif )


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[This message has been edited by Dave McRoy (edited 06-25-2001).]
 

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Discussion Starter · #4 ·
What I'm finding is only on digital channels. I don't use the antenna for analog signals, only DT channels. (I have cable for the analog signals)


I'm using a Channel Master 4248 antenna with a rotor and CM 7775 UFH-preamp.


Here's what I'm seeing:

Philly channels: I'm getting between 60 and 70 signal strength, but am seeing a fair amount of multipath and drop outs. The towers are about 45 miles from me. Before I installed the antenna, I was able to get a lock on WCAU (NBC) in Philadelphia, which is operating at only 25% power. Since the installation of the rotor, I'm not getting a lock at all.


NYC channels: I'm approx 70 miles away, but I'm getting spikes in my signal up into the 60's but then it drops off. Not enough or not stable enough to lock on to. There are other folks in my area picking up the NYC channels, and considering they are broasting off the World Trade Center, there should be plenty of signal. I can almost get a lock on WCBS and WPIX, but it's not stable.


Adjusting the antenna itself up or down really isn't an option considering where it's mounted. I'd really like to get WPIX (WB) and WWOR (UPN) from NYC. It just kind of bothers me that since I installed the rotor, I'm not getting as strong a signal on some channels. I have yet to verify that the mast is level up and down, but it looks like it from the ground. I thought perhaps boosting what little signal I have might be enough to lock.
 

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Quote:
Originally posted by Randy Boecker:
Before I installed the antenna, I was able to get a lock on WCAU (NBC) in Philadelphia, which is operating at only 25% power. Since the installation of the rotor, I'm not getting a lock at all.
Adding another amplifier could also end up increasing the noise level. It sounds like you're probably getting multipath on WCAU amplified to a level that prevents lock. Further amplification would not help in that situation. However, if you can lay hold of another amplifier with the understanding that it can be returned, trying your idea won't harm anything.

 
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