I have 3 modulated channels combined with RF out from sat receiver. This currently feeds 3 TVs (will possibly be adding 2-3 in the future). All coax runs are rg6, under 60'. My modulated channels are comming from 3 seperate modulators with a 20db out. Modulated channels goto 3-way splitter, 3-way into 2-way to combine with satellite, then to TVs. Do I need a video amp? Any other input/advise would be appreciated. Thanks in advance...

-J

Always use variable gain modulators for a start.

And I doubt you should need an amp if the work is done properly. What splitter/combiners are you using?

How many runs?

How do the pictures look? Any funky lines or waves or such? If not, you should be all good. Just remember, a modulator is only RF out so video quality will be fair at best.

J, hopefully those modulators have attenuation. Looks like you did it right, but I'm wondering if it's going to be a hot signal.

Make sure you have a few channels separation between each mod. channel, that may help.

Thanks for your replies...

I have 3 CE Labs 1 ch modulators (1001F). I went with these mainly because they were cheap! Much cheaper than buying a 3 ch modulator. I will probably upgrade in the future when I want more channels. There is currently 3 runs, I will be adding 2-3 more soon. All spliters/combiners are Regal 1000mhz (Left over from when I used to install cable modems!). The picture was fine when I just had 1 modulator. Once I added the other 2 I got a vertical wavey line going across the screen on all 3 channels. Channels are set 1 apart (121, 123, 125). Should I add a filter? I didn't think I needed one since I wasn't combing the channels with others. Thanks again for your help.

-J

Sounds like a hot signal. Play with modulator outputs by adjusting them down. If no adjustment is available, try putting a 3 to 6db pad on the output.
That vertical line showing up after you added the other 2 modulators leads me to believe you may be on a channel that may have some cable data or digital video moving on it.
So try experimenting with other channels. I have even broken them up so that one channel would be on ch 42, another on ch 88 and another on ch 124.

Seperation of channels is a must. While I can understand the use of cheap mod's I wouldn't recommend it. Service calls are more expensive than the mod's in the long run.

To this point you have not suggested that you are having any problems. More info would be good. And you don't mean a video amp, because if there is a channel, it is RF, not video.


Aha! A problem to solve!


The other guys are right -- this sounds like too much signal. Each modulator puts out a particular amount of power, and when you add modulators, you pump more power into the TV inputs, even though each channel is not at any hotter a power level than it was before.

It also sounds like the channels are too close together. Until a few years ago, million dollar modulators (commercial TV stations) did not dare leave less than one channel between one another. It would be truly amazing if you could always get away with such close spacing with a modulator (your own little TV stations) that undoubtedly lack a commercial TV station's strict frequency and bandwidth performance.


Please suggest what kind of filter you are thinking of, and to do what. I don't get it.


You mean combining, right? If you are not combining these channels with others, why are they at such high frequencies? Try lower frequencies, UHF 14, 18, 22 or cable 65, 69, 73 (same frequencies, almost). Again, more info is needed...do you also distribute a cable signal, and you had to go that high to find unoccupied channels?

Thannks again for all your replies. I am not distributing any cable. Just satellite, which is being modulated to channel 3 by the sat receiever. The reason I put the channels so high and close together is because I don't have the remote for my kitchen LCD. This way the channels are easily accessed using the channel up/down on the TV. If I try using the automatic channel tune feature on this TV (to remove channels with no picture), it keeps every channel! I will try adding pads and seperating the channels some more.

As far as a filter goes, I have read that when modulating channels you must use a low pass or notch filter. From my understanding these are only needed when combining with existing cable channels, right? Do I still need one just to make sure the channels are clean before adding my own?

The main reason I asked about a RF amp (thanks for correcting me Ernie) is because everything I have read about distributing video over coax has said to use them. I just wasn't sure is they were needed since all my runs are under 60'.

Thanks again. You have all been very helpful...

-J

Okay. That makes total sense.


INFO INFO INFO DON'T YOU GET THAT WE CAN ONLY HELP YOU IF YOU TELL US WHAT FREEKIN EQUIPMENT YOU ACTUALLY HAVE ? ? ? ? ? ? ??? ??

Okay, now that I have stopped twitching:
I can go down to the local drug store and get something for this cough, and while I am there I can spend ten dollars and get a little remote that will operate any one of thousands of models of television! It might take up to twenty or thirty dollars to get one with an actual MENU button on it for programming your TV, but that depends on the TV.

By the way, if you autoprogram a TV and no signals are present, many TVs will simply leave all channels programmed. You HAVE done this with all signals present, right?


Right. If your cable distribution system is not hooked up to cable or an antenna, there will be no need for a filter.


I'll have to show that quote to my wife next time I correct her about something. Thank you for taking it so well.


Amps are necessary if the signal levels get too low. I bet "everything" gives some conditions about when to use them. With analog TV, snow is an indication that you need an amp (or that you are mixing cable and modulated signal and the cable is goosing your signal with noise).

I meant TRY to correct her, patient soul that she is.

Ah, hell, I'm posting every couple of minutes like Mr. Stanley did for a while!

LOL... Thanks again. You have been very helpful...

I am here to learn, I appreciate when someone takes the time to answer my question or correct me if I am wrong.

The TV in question is a Samsung 17" LCD (LTM1775W). I have tried 3 or 4 universal remotes and none of them work that TV. Samsung parts wants $50 for the remote.

Anyway, I seperated the channels more (115, 120, 125) and the picture quality improved some. I still get the vertical line, but its not as bad. The auto program now works too. And yes, all signals were connected when I did it the first time! Is there any benefit to the channels being lower? Since the auto program is now working, it doesn't really matter where the channels are.

-J

I used the Channel Plus and it worked like a charm especially being able to do IR over the COAX.

Marc

Yeah, well I've slowed a bit since my Ritalin ran out!!!