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Need Advice on Video Distribution


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14 replies to this topic

#1 OFFLINE   rrp13

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Posted 04 March 2012 - 04:30 PM

Here is what I have and what I am hoping to do. Currently I have a cable tv package and a Dish 722K DVR. I also have a Channel Plus frequency-agile multi-channel modulator. My intention is to send the composite signal from TV1 & TV2 along with a couple of other sources as CATV channels out of the modulator. I would then like to combine those modulated channels with the cable tv channels and send all channels to 3 TVs (1 in each of our 2 bedrooms and 1 on our dock).

So, I'm thinking I need something with 2 coax inputs that will combine the modulator and CATV signals and then have at least 3 coax outputs to go to the 3 TVs I want to send signal to. Also, I assume this "something" would need to amplfy those signals it is sending out? Don't need to boost, signals are good as is. I already have RG6 cables runs in place. So, I'm looking for suggestions by make, model, etc. Links appreciated. Thanks.

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#2 OFFLINE   John Williams

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Posted 04 March 2012 - 08:04 PM

You simply have a 2-way combiner (which is a 2-way splitter turned backwards), then a male to male barrel (or short coax jumper), into a 3-way splitter.

On the 3-way splitter, you'll have 1 port (first port from input side) that has less loss than the other 2.
On the 2-way, you'll most likely see a loss listed of 3.5dB; please note that is for VHF frequencies. The higher the frequecny is, the more those thru a splitter (and cable, etc...). You are modulating in UHF with that Channel Plus, so figure at least a 11dB loss from start to finish (thru splitters and coax) on the high output of the 3-way (I would send that to the Dock - as that's probably your longest run - you didn't tell us). And 15dB of loss thru the other 2 ports of the 3-way (send those to the 2 bedrooms). Your Channel Plus modulator outputs 25dB of signal. So you should end up with about 10dB of signal at the TV's for your modulated channels.
Now assuming your CATV is coming in at 10dB (needs to be measured), then you will need a small 10-15dB amp on your CATV to match signals.

Now!!! Since most all the frequency is used on the CATV spectrum. Where do you plan on inserting those channels and how are you planning on filtering those out in the CATV? Channel Plus makes some channel filters (low pass filters). I'm assuming you don't use digital cable at all (no boxes at all from CATV), so only a few lower analog channels.

[edit]: The above dB loss assumes solid copper, quad shield, RG6 was used with runs under 100ft for bedrooms. And under 200ft for dock. If a cheap copper/clad steel RG6 was used and/or runs are over 100/200ft, losses will be higher but should still work fine. You should still be above 0dB at TVs.

Edited by John Williams, 04 March 2012 - 08:18 PM.


#3 OFFLINE   rrp13

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Posted 04 March 2012 - 08:46 PM

OK, well, I knew about the splitter turned around backwards, but I was afraid that and a 3-way splitter would result in too much signal loss. And, yes, you are right that the run to my dock is the longest run. I'm not against spending some money to make sure I have plenty of signal pushed to each TV. Of course, I don't want to spend it if it isn't necessary. So what is a good 10-15db amp to get?

On my modulator I can assign channel frequencies between 65-125 on the CATV channels. There is no cable box involved but, some of the channels are digital (ATSC?). It's just a basic package and the channel numbers don't go much above 100. Pretty sure I can find 4 open channels.

I know that RG6 was used for my runs, the quality of it? Guess I will find out. Right now it carries the RF Home Distribution from the 722k out to the dock with no problems. Just looking to send everything I have to all TVs.

#4 OFFLINE   John Williams

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Posted 04 March 2012 - 09:24 PM

I can't remember what the RF Home distribution dB output is on the 722K. I do remember it was slightly less than 25dB (probably 15-20dB). So your final signal to the dock will be 'about' the same or just 5dB less than you have now.

As far as the cable amp goes. You really need to know what you're working with to know what you need to do. If the cable company has done thier job well, you should have a nice 10dB to 15dB signal coming into your house. In that case you could use a nice amp like this: http://www.amazon.co...Y/ref=pd_cp_e_0

If however you only have -5dB to 0dB coming in, you might need a 25dB to 30dB amp. Your cable probably wouldn't look that great with such a weak signal coming in, however.
If you have a 20dB signal coming in, then you don't really need an amp on it (unlikely you would have a CATV signal coming in that hot). Trying to put an amp on this would actually cause problems.

I know most people don't have RF signal level meters (heck, a lot of 'so called' professionals don't either). See if you can get a cable TV tech out to your house to measure it for you.

#5 OFFLINE   rrp13

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Posted 05 March 2012 - 06:54 AM

OK, it will be a couple of weeks before I get there to apply any of this. Since I don't have a signal level meter and getting a cable guy there is next to impossible with my work schedule, I think it's best if I just go with the reverse splitter into the 3-way and just see what I get. From there I can determine if anything needs to be amplified.

Thanks John for jumping in and hashing this out for me. Anything else I should be aware of?

I'll be sure to report back my results in a few weeks for anyone wondering how it turns out.

#6 OFFLINE   John Williams

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Posted 05 March 2012 - 10:26 AM

That should get you going, just make sure to use good quality RG6 ends (compression type) for your fittings.

I would go ahead and get one of those cable amps. The odds of you having a hot signal (over 15db+) from the CATV, are about the same as you getting struck by lighting (or close to it anyway). And like I said, if your signal was really low (below -5dB to 0dB) you would already be having issues with CATV after splitting it off to your rooms you have now.

#7 OFFLINE   harsh

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Posted 05 March 2012 - 10:49 AM

The problem with trying to combine CATV with anything is that, for most CATV systems, the spectrum is completely full. You need to notch out a space to put your own channels in or they're going to get clobbered.

The problem with notch filters is that they typically whack 5-6 channels in a row.

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#8 OFFLINE   John Williams

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Posted 05 March 2012 - 11:37 AM

Now!!! Since most all the frequency is used on the CATV spectrum. Where do you plan on inserting those channels and how are you planning on filtering those out in the CATV? Channel Plus makes some channel filters (low pass filters). I'm assuming you don't use digital cable at all (no boxes at all from CATV), so only a few lower analog channels.


Covered.

Without knowing your channel assignments available, it's hard to recommend a channel filter. The Channel Plus filter I would recommend without knowing the above info, would be the NF-469: http://www.smarthome...HF-14-19/p.aspx

#9 OFFLINE   rrp13

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Posted 05 March 2012 - 12:00 PM

Right now, there's no issue with the cable but, it is only split to two TVs currently. Where is the best place to put the cable amp for my purpose? Just in front of the two-way splitter I'm going to combine the signals with or at the entry point of the CATV into the house?

As far as assigning channels to my other sources on the modulator, here's the channel lineup: http://www.citizensc...up_LakeArea.htm. There's a gap in the 70s and 80s that show no channel assignments. I'm hoping to be able to assign in that range. Also see that 108-125 are not listed as having anything there. I could be way off in my assumption but, until I get there and actually try it, I can only assume right now.

I will be "moving in" starting the 14th of this month so, I hope to be able to tackle this on the 16th or 17th.

#10 OFFLINE   John Williams

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Posted 05 March 2012 - 12:40 PM

As far as assigning channels to my other sources on the modulator, here's the channel lineup: http://www.citizensc...up_LakeArea.htm. There's a gap in the 70s and 80s that show no channel assignments. I'm hoping to be able to assign in that range. Also see that 108-125 are not listed as having anything there.

OK,
1st) Cable channels 95-99 are special use channels. They actually reside in frequency between channels 6 & 7 VHF. You'll notice in the owner's manual that your Channel Plus modulator (UHF) won't do those channels.
2nd) All 3 digit channels on your cable system are 'digital' channels for cable. Meaning you HAVE to have a digital cable box to get them. Also, the frequency these channels are located at have nothing to do with there channel number. They are mapped according to the cable provider to the box.
3rd) The highest channel in frequency that you will be receiving is channel 67 (486MHz on the top end). So the next filter that will work from Channel Plus is a LPF-600: http://www.smarthome...-CATV-86/p.aspx
This will allow you to insert any cable channels above 86.

The cable amp needs to go in-line before the 2-way combiner. Also, need to put the channel filter in-line before the amplifier.

#11 OFFLINE   rrp13

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Posted 05 March 2012 - 04:05 PM

Apparently, I am having trouble reading, I see that all my questions are pretty much answered above, I just need to make a couple of purchases and try it all out next week.

Thanks, this has been a nice learning experience.

#12 OFFLINE   rrp13

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Posted 05 March 2012 - 04:10 PM

One more thing, I assume I can assign my first channel on the modulator to 86? Then I have to skip a channel for my next assignment so, I would go 86 88 90 92. Or should I start at 87 or 88 and go up from there?

#13 OFFLINE   John Williams

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Posted 06 March 2012 - 12:56 PM

That particular filter says you can start inserting at channel 86, so you should be good.

#14 OFFLINE   rrp13

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Posted 06 March 2012 - 01:52 PM

Excellent, I'll let you know how it goes...

#15 OFFLINE   rrp13

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Posted 15 March 2012 - 01:24 PM

Just finished hooking everything up. Works perfectly! Signals are strong to all TVs and my 4 modulated channels fell right in at 86 88 90 92. John, I can't express my deep appreciation for your patience with me and your stellar advice. I owe ya a few nice cold frosty ones my friend...




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