Need Help Please - Condo building at sealevel -roof at over 100 feet.

[aztech]

Here is my situation:
http://www.tvfool.com/?option=com_wr...d2437452c73e0d

I set up a proof of concept for our HOA. I did a test using a DB8X. All the San Diego network channels comes in well - except the CW channel 23 (virt 6.1) fades and sometimes is out completely. I have approval to install 2 systems 1 for each building. I need to get the CW San Diego channel.

I thought of using an HD7968P - since it doesnt look like I need low VHF. I was going to use Channel Master 7777 pre amps at the mast with the power in the fourth floor closet. Each building is four floors with a north and south closet.

Each fourth and third floor closet would feed 6 condos each. and the 2nd floor closets would feed 12 condos each (takes care of 1st and second floors)

I was planning to add distribution amps at each floor closet as needed.
Does this sound like a workable solution and plan? I thought if the 7968 didnt provide enough gain, my only other option would be to stack another DB8?

Any help would be greatly appreciated!
Thanks,
--James

[Tower Guy]

The DB8X is not the best starting point. It has a narrow beam pattern on UHF that would drop the CW at 157 degrees down roughly 3 db from the other SDgo channels at 143 degrees. In addition, the DB8 is not rated for VHF and you have both channels 8 and 10 on VHF.

That said, the CW is 30 dB weaker than the SDgo channels. That can work in a single house, but not as well in an MATV environment.

The right antenna may be a medium gain 7-51 antenna such as the HBU-44 or HD7694P. My favorite would be a DB4e aimed at 150 degrees coupled with a Y5-7-13 aimed at 162.

[aztech]

Thanks for the reply. Do you think a single antenna such as the 7968P has a chance of doing it all? I can locate it anywhere on the large roof on a nonpenetrating roof mount and even add a couple of 5 foot mast sections.

If that doesnt do it, I could combine another antenna or stack another.

I was going to use a CM7777 pre amp and then split to north and south closet runs at 4th floor. What is the best distribution amps to use at each floor?

I just hope I get the signal strong enough to feed the whole building of 48 condos - if everyone signs up for it.

--James

[aztech]

I installed a CM7777 pre-amp and it resulted in the loss of several channels. I checked voltages at the preamp and 22V was present, so I am sending it back. Can a preamp with only a single input be used with a splitter/combiner that is combining two antennas?

[ADTech]

The signals in your area are far too strong for a high-gain amp like the CM7777. Here's a simple rule of thumb: If there's any green on your TVfool plot, do not use it. You can probably pad down the input with some attenuation and use it anyway since you already have it on hand. Get a couple of 3 and 6 dB attenuators and have at it. Or, just return it and get a medium gain amp that can handle the moderately strong signals.

Can a preamp with only a single input be used with a splitter/combiner that is combining two antennas?

Sure, we do it all the time. Here's a diagram I did a couple of years ago that demonstrates it in a generic manner: https://www.antennasdirect.com/cmss_...e_Antennas.pdf

[aztech]

More like a CM7778? ALso, what would you recommend for a distribution amp for a 1 X 6? Thanks so much for your help!