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Trouble splitting preamp signal to 2 TV's

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Old 08-24-2010, 12:49 PM   #1
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Default Trouble splitting preamp signal to 2 TV's

I get one or the other TV to work... do I need to get a multiple outlet pre-amp? Using CM7777 now.
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Old 08-24-2010, 02:42 PM   #2
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Hi, Mark

So, tell us how you are splitting the signal between the two TVs now. It may be something as simple as a bad splitter.
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Old 08-24-2010, 03:18 PM   #3
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two thirds of the post went missing somehow. Here is what was mentioned.

Have a 30 ft mast with said CM7777 and happy with it. Most feeds are 70 miles distance. Have about 100 total ft of R6 (antenna to TV).

Went outside where all the CTV runs are to hook up a second TV (with a common 1 to 2 splitter) and nothing. Can choose one or the other but not both ... is this normal? Not a problem if it is, willing to get whatever is required.
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Old 08-24-2010, 04:14 PM   #4
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The CM 7777 works best if you have the mast head amplifier as close as possible to the antenna and the power injector as close to the television as possible.

If you connect a television between the mast head amplifier and the power injector - you have to use some sort of voltage block.

ALSO - the cable block isn't always the best point to connect the antenna to the televisions. It is probably better to come indoors with the feed line and then split it after the power injector with two equal lengths of wire, with a splitter that is unilateral - that means two equal signals comes out the other end.

A splitter is just like a magnification glass in reverse, with a unilateral splitter when a person walks in the input port, two smaller people walks out the output side. Each persons arms, legs, torso etc are the exact same size. Other cheaper splitters - you might get one person of one side and another person of a much smaller size walk out the other side.

My guess is that what ever the cable company or sat dish company had installed on the outside of the house - isn't designed for use for a regular old antenna and should not be used for that purpose .
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Old 08-24-2010, 05:49 PM   #5
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OK so the 7777 is installed properly right at the antenna and powered down by the TV. The other TV is 50 ft away ... equal wire distances would have 50 ft coiled up somewhere. That is if I understand what Columbo is saying?
Short of rewiring the house, is there another way ... perhaps replacing the 7777 with a dual output pre-amp or a powered distribution amp like rinardman (CM3043)? What kind of voltage block are you referring to Columbo?
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Old 08-24-2010, 06:20 PM   #6
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The wire after the splitter doesn't have to be the same length.
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Old 08-24-2010, 07:07 PM   #7
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baud is right, keep coax runs as short as practical.

What is the splitter you are using? You say you can get one, or the other TV to work. Do you have to change the wires around to switch which one works?

Have you tried a different splitter?

The CM 3043 I use is a distribution amp, used to compensate for signal loss on long cable runs. It replaces a splitter, in my case. You may not need one if your signals are strong enough.
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Old 08-24-2010, 09:00 PM   #8
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Using cheap 5 dollar splitters like you'd find at Radio Shaft ....didn't think it mattered. One is a Regal 3.5 Db DS2DGH10 the other one can't be found at the moment.

Correct, each TV works separately but not in tandem.
So let me try again with another brand, you say a common splitter should work right?

If it won't work a distribution amp is a possibility and it will not be damaged by the pre-amp voltage?
Signal strength here is 65 - 85 % for most channels so maybe it will not be over driven if I go with an extra TV and 50 more ft of coax.
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Old 08-25-2010, 07:54 AM   #9
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You won't need a preamp and a distribution amp.

Both amps inject a little noise along with the signal. Too much noise is worse then not enough signal.

The television tuner actually has a little amplifier built into the tuner that is more then powerful enough to receive what you give it, amplifies it some and then cuts it back down to a usable level before it sends it on to the tuner.
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Old 08-25-2010, 02:26 PM   #10
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Been experimenting a bit.
Don't get a signal to any TV using the splitter and one end open (un-terminated). Can it be that both new splitters malfunction or does it call for termination?

Only way to get a signal is with a single barrel connector?

Using this thinking - What if a second CM7777 or lesser sized pre-amp power source was on the other TV ... the two pre-amp powers would meet at the splitter?
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Old 08-25-2010, 03:11 PM   #11
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That Regal splitter is a decent one .. the one you have has blocking caps so if you are using the power inject AFTER the splitter, odds are the preamp is not receiving any power. Move the splitter to a point after the power injector.
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Old 08-26-2010, 09:42 AM   #12
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Found the other splitter - Extreme BDS102H, 3.5 db.

ericspenser, both Regal and Extreme sites says these do not pass DC voltage so any power from a pre-amp is pre-empted (pun intended).

Getting a power passing splitter and one V. block as per Columbo to try again.

really thot that splitters were such a low-tech item it didn't matter.
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Old 08-26-2010, 01:05 PM   #13
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Quote:
Originally Posted by mark steffler View Post
Regal and Extreme sites says these do not pass DC voltage so any power from a pre-amp is pre-empted (pun intended).
What prevents you from installing the splitter between the power supply for the 7777 and the TV sets?
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Old 08-29-2010, 02:46 PM   #14
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tower guy jogged some loose rust somewhere. my mind could not deal with what you guys we're telling me (over and over). Needed a schematic to see what was going on here and it helped alot. Thanks for your time as all is OK now. Splitter properly placed.

once again, Thanx to all.
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Old 12-19-2010, 07:03 PM   #15
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Sounds like the same situation as described in another forum.

see the following:

(you can find it searching for "Power Passive Splitters" in avsforum dot com )



Power Passive Splitters
I currently have an antenna in my attic feeding 2 TVs through a conventional 2-way splitter. Here's a rough illustration:
Code:

. . . . . . . . . . . . . . . . ---> TV1
antenna ---> splitter
. . . . . . . . . . . . . . . . ---> TV2

I am thinking of adding a Channel Master CM7777 pre-amplifier to my antenna. It would look something like this,
Code:

. . . . . . . . . . . . . . . . <---> cm7777 power ---> TV1
antenna ---> CM7777 <---> splitter
. . . . . . . . . . . . . . . . ----> TV2

I understand that I cannot use the same passive splitter since not enough power from the CM7777's power unit can get through that splitter to the CM7777 pre-amp. Plus, even if it could, I am concerned that the DC might feed back to TV2.

I've recently learned that there is another kind of splitter called a power passive splitter. One such example is the Eagle Aspen P7002AP (found at the SolidSignal dot com site).

As I understand it these kind of splitters will pass all the CM7777's power unit power through to the pre-amp so it looks like the kind of splitter to use. But I am still concerned about DC feeding back to TV2.

The P7002AP documentation says it's "all port power passive". There's also a P7002 and its documentation says it's "single port power passive".

So if these splitters are the kind to use which one should I use? Or does it matter? Will either block all the cm7777's power unit DC back to TV2?


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