Pre-Amp / Line Amp combo question.

m00d · 01-13-07, 03:59 PM

Hi,

My antenna is 200 feet from my house which forces me to use 250 feet of rg6 to
reach my HTPC. I have a new 300 foot roll of rg11 in hand which I will be installing
in a few days, hopefully this will recover 3 or 4 db of signal. But even with this
increase I believe I am going to need to use a line amp in addition to my mast
mounted cm7775. My HTPC has two tuners and if I use a standard
splitter to feed both tuners I loose two of my weak channels.

My question is can I use a line amp along with my mast mounted cm7775?
And if so how much cable length do I need to put between the cm7775 power
supply and the line amp? Also, is a line amp the same thing as a distribution
amplifier? It seems they both simply amp the signal while the distribution amp
also splits the signal. I read somewhere that putting a line amp to close the the
preamp power supply can cause problems.

Thanks!

kenglish · 01-14-07, 10:36 AM

It will all depend on signal levels coming in and the levels out of the amp. Strong signals, whether they are TV transmitters or something else, can overload a preamp. Strong signals from a preamp can overload a tuner or a distribution amp.

Here at KSL, we have our antennas on the roof, and have about 600 feet of RG-11 coming down to the basement headend. With UHF, the 20 dB preamp overloads slightly, already. We still have enough to usually split 8 ways. I added a 7 dB distribution amp to get levels up slightly, and to split 16x, but it's borderline on overload. Plus, we have two dozen stations in the UHF band.

Similar thing with VHF-HB (7-13). We get plenty enough signal to overload a preamp already, so we have to attenuate it at the antenna.

We still have sufficient signal on VHF-LB (2-6), via 300-400 feet of RG-6, with no preamp.

So, I'd say....try everything without amps, using the RG-11. Then, try preamping the UHF only. If necessary, then try a separate preamp just for the VHF-HB if needed. Your CM dealer should be able to suggest whatever multiplexers you might need to add the second preamp.

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m00d Member Join Date: Mar 2004 Posts: 103	Pre-Amp / Line Amp combo question. Hi, My antenna is 200 feet from my house which forces me to use 250 feet of rg6 to reach my HTPC. I have a new 300 foot roll of rg11 in hand which I will be installing in a few days, hopefully this will recover 3 or 4 db of signal. But even with this increase I believe I am going to need to use a line amp in addition to my mast mounted cm7775. My HTPC has two tuners and if I use a standard splitter to feed both tuners I loose two of my weak channels. My question is can I use a line amp along with my mast mounted cm7775? And if so how much cable length do I need to put between the cm7775 power supply and the line amp? Also, is a line amp the same thing as a distribution amplifier? It seems they both simply amp the signal while the distribution amp also splits the signal. I read somewhere that putting a line amp to close the the preamp power supply can cause problems. Thanks!

01-14-07, 10:36 AM	#2 \| Link
kenglish AVS Special Member Join Date: Jan 2000 Location: Salt Lake City, UT, USA Posts: 3,787	It will all depend on signal levels coming in and the levels out of the amp. Strong signals, whether they are TV transmitters or something else, can overload a preamp. Strong signals from a preamp can overload a tuner or a distribution amp. Here at KSL, we have our antennas on the roof, and have about 600 feet of RG-11 coming down to the basement headend. With UHF, the 20 dB preamp overloads slightly, already. We still have enough to usually split 8 ways. I added a 7 dB distribution amp to get levels up slightly, and to split 16x, but it's borderline on overload. Plus, we have two dozen stations in the UHF band. Similar thing with VHF-HB (7-13). We get plenty enough signal to overload a preamp already, so we have to attenuate it at the antenna. We still have sufficient signal on VHF-LB (2-6), via 300-400 feet of RG-6, with no preamp. So, I'd say....try everything without amps, using the RG-11. Then, try preamping the UHF only. If necessary, then try a separate preamp just for the VHF-HB if needed. Your CM dealer should be able to suggest whatever multiplexers you might need to add the second preamp. __________________ Ken English, Sr. Engineer, KSL-TV/-DT. "Not a REAL Engineer, but I play one in TV"