Do I need an Antenna Pre-Amp?

[slydog75]

I'm going to be getting the DB4 and roof mounting it. I'll be using a 100ft coax and was wondering if I will need to get an antenna Pre-Amp due to the 100ft of coax between the antenna and the HR10-250. I'm currently looking at the PA-16 seen here:
http://www.antennasdirect.com/antenna_amplifier.html

[Redux]

wondering if I will need to get an antenna Pre-Amp due to the 100ft of coaxA concern with a preamp is overload. If your channels are all of moderate strength there shouldn't be a problem. But if you've got one or more very strong channels the amp may do more harm than good.

I think it's almost always a good idea to try first without an amp and go from there. 100 feet of good RG-6 is not going to kill a good signal in the low/mid-UHF range (say channel 40 or below).

Winegard makes a preamp it promotes especially for potential overload situations. Its specs are even worse than the amp you're looking at, but if it turns out you have a mix of strong and borderline channels it might be just the thing.

[TyroneShoes]

It depends upon the signal strength at the input to the receiver, and the signal strength at the input to the amp. If you are 40 or more miles away, you may need a preamp, but if you are generally not that far, you may not, but a line amp placed after the downlead could still be very helpful.

Preamps are usually placed immediately after the antenna if the signal is exceptionally weak, because if not, the noise figure in the amp will react with the weak signal and relatively high noise floor to create a lot of noise at the input to the amp. If you have a very weak signal and a long cable run, the signal may be so attenuated after the cable run that an amp placed there will not work properly, so in that case, a mast-mounted preamp can be helpful. But this is not as important for DT as is is for NTSC, because DT can tolerate a lot of noise without any PQ degradation at all (although too much noise will eventually cause pixellation or loss of digital lock).

If you go to post 21 in this thread:

http://www.tivocommunity.com/tivo-vb/showthread.php?t=288925

I have laid out a technique that anyone can use to determine what the proper amount of amplification (using a line amp placed after the cable run, not specifically a mast preamp) or attenuation might be needed. It uses the signal quality meter in the Tivo, and there is no necessity to actually measure or know what the raw signal carrier strength is. And it works really well.

[jfelbab]

I'm going to be getting the DB4 and roof mounting it. I'll be using a 100ft coax and was wondering if I will need to get an antenna Pre-Amp due to the 100ft of coax between the antenna and the HR10-250. I'm currently looking at the PA-16 seen here:
http://www.antennasdirect.com/antenna_amplifier.html

Typically, 100' of RG6 coax will insert 5 db of signal loss. That means only a little over 1/4 of the original signal from your antenna will reach your HR10-250, assuming you don't have any other splitters on the run. Now that may still be enough signal to receive your stations but frequently when I have a runs of 100 foot I have needed to add a preamp. As Redux suggests try it first and if the signals are too low add a preamp.

[slydog75]

According to antennaweb I'm between 35 and 37 miles from the transmitters. I know with NTSC, back before DirecTV offered locals, we had a heck of a time recieving Fox at all and the other locals looked like crap.

[TyroneShoes]

At that distance, you have a good fighting chance, unless there are significant terrain obstructions. The DB4 might not be the best choice, I would go with the DB8 or a 4228. That will give you the highest gain and best directionality, and will give you the best chance of having enough signal to avoid needing a preamp. The Channel Master 7775 and 7777 units seem to work the best if you still need one.