the right modulator for me - AVS Forum
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post #1 of 27 Old 12-01-2000, 10:45 PM - Thread Starter
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Hi all....thanks for all the great advice/help...

quick question. I just received a miniature 3 channel modulator ( http://www.smarthome.com/7762.html ) and I hooked it up to distribute the signal coming out of my tivo. Problem is, the signal upstairs in the bedroom isn't strong enough from this (picture is quite fuzzy). I put a signal amplifier ($20 one from radio shack) on the output of the modulator and this improved the picture upstairs slightly, but definitely not enough. So, I'm pretty sure I need to get a better modulator and I'm curious what you all recommend....

thanks for any answers....


[This message has been edited by normpaperman (edited 12-02-2000).]
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post #2 of 27 Old 12-03-2000, 01:22 PM - Thread Starter
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Quote:
Originally posted by peepsdontlistentome:
what is the DB out put of the modulator? A VHS mod should have enough pull to run upstairs. Perhaps you have a cable/ connector problem. Swap the VCR with the mod, to see if the problem is the same. A 10DB boost from the Shack should be fine. Are you using DB taps, or splitters? Is there a tweak on the DA?
I had originally tried just using the vcr's ouput, but its signal wasn't strong enough to go anywhere (the tv upstairs showed nothing). There is 1 splitter at the source (3 way splitter, 1 goes into tv, 1 into Tivo, 1 into mod) and then a 4-way splitter in the garage where the signal gets sent to all the tvs in the house. I'm still coming up to speed on all of this....what's a DB tap? tweak on the DA?

Thanks!

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post #3 of 27 Old 12-05-2000, 08:57 AM
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I assume that's a passive splitter. RS has a 1 in 5 out distribution amplifier that's decent. You should have no problem with 100 -150 ft runs

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post #4 of 27 Old 12-05-2000, 10:01 AM - Thread Starter
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Cool...now I have 2 things to try tonight.

As for the tv upstairs...I don't think I've said this yet, it's definitely not high quality. It is a 27" sansui (anyone else have one of them?) tv/vcr combo. It was a great tv (big) in college, but it's pretty far from top of the line, so you're right....could very well be a problem in that set....
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post #5 of 27 Old 12-05-2000, 09:15 PM - Thread Starter
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Thanks everyone....

I just got off the phone with smarthome and they recommended that I just purchase this 18dB Fixed-Gain 40-1000 Mhz Signal Amplifier
( http://www.smarthome.com/7709.html ). It's $109...does that seem like the right way to go? Or is that radioshack thing better for me? I have a cheap rs signal amp that I've put on the line from the modulator and that improved the signal _slightly_ but not to a signal I'd like to watch.....
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post #6 of 27 Old 12-05-2000, 09:33 PM - Thread Starter
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Thanks for the advice...I'll give that a try when I get home tonight.....
Don't know if this makes a difference...I've taken the output from the Tivo and run a wire up the stairs to the tv and that worked fine....but if I take that output and just put it into the splitter down there, I get no signal upstairs....I'm guessing that output is just not powerful enough after the 2 splits to have any decent signal upstairs, especially on channel 3 (since I've got a channel 2 and a channel 4).....
My hunch is that I will have the same results using the modulator (or the vcr) for that matter....
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post #7 of 27 Old 12-05-2000, 09:53 PM
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Careful...

It may be the tuner in the TV!

In our master bedroom, we have a nice RCA 27inch, that was top-of-the-line back in 1980. Great picture, plenty of AV connections, etc. Still has a great picture.

It has digital tuner, but separate inputs for UHF and VHF.

It could not tune in any of the modulators I tried - the 3-channel simple unit (similar to yours) as well as the Sony MRD-D1 dual channel mod (similar to Channel Plus 3025.

problem was due to cable run length (about 100ft) as well as poor sensitivity on the higher channels (64+ for CATV setting, 14+ for OTA setting of tuner).

Solution?

Purchased a cheap VCR (picked up Panasonic PV4540 for $77 at Best Buy), and I use it as the tuner. Added plus - VCR remote can control TV + VCR + DSS.

I have the remote IR targets with the Sony mod.

To verify, move your TV closer to your mod temporarily with shorter piece of coax. I did this to verify TV tuner was indeed working.

So why didn't an in-line amplifier work? Don't really know, and I did try this too.


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post #8 of 27 Old 01-01-2001, 06:56 PM
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If you want junk go ahead and get a Channel Plus, otherwise check out http://www.cable-electronics.com/
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post #9 of 27 Old 01-03-2001, 07:21 PM
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Quote:
<font face="Verdana, Arial" size="2">Originally posted by bb80301:
mkaylor:

You should also disclose your association with this company (i.e., all of the senior management is also named Kaylor).

That said, we're all interested in learning about these types of products & welcome your input.

</font>
Further to that point, the resume on Mike's home page indicates he worked for Cable Electronics from 1995-97. Mike, IMHO it's pretty shady for you to slam a company's product without telling us that you worked for (and appear to be related to) the competition you are recommending. If you can shed some light on technical reasons why CEI's products are better please share with us.

For the sake of completeness, I am not associated with either company, nor do I have any personal experience with their products.


Now back to the original topic. Norm, if you only have signal strength issues with the cable going to your upstairs tv, then put the amplifier on the splitter output that goes to that tv. With the amp located prior to the splitter in your current configuration the distortion you see on your other tv's is caused by overloading their tuners. Amplifying only the signal in need will avoid that problem.

Cheers,
Matt
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post #10 of 27 Old 01-03-2001, 09:08 PM
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Quote:
<font face="Verdana, Arial" size="2">Originally posted by mkaylor:
If you want junk go ahead and get a Channel Plus, otherwise check out http://www.cable-electronics.com/</font>
mkaylor:

I'm not defending ChannelPlus, but you really should give some specific reasons why ChannelPlus products are "junk" and why these products are better. You should also disclose your association with this company (i.e., all of the senior management is also named Kaylor).

That said, we're all interested in learning about these types of products & welcome your input.

Thanks and regards
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post #11 of 27 Old 01-03-2001, 09:08 PM
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I just happened to have installed many many modulators. Just last year I worked on a house boat which I had to modulate 19 items (on top of 37 CATV channels), CCTV, VCRs, DVDs, computer... Well I loved CP and needed another CP modulator overnight as this project was comming together fast and changing daily. CP was not available via my normal channels so I took the Cable Electronics option from my wholesale company.
Well the Cable electronic looked and acted like crap so it want back and a CP went in.
For consumer modulators CP is king. IMHO.
Channel Vision is second.

Dave


[This message has been edited by David Richardson (edited 01-04-2001).]
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post #12 of 27 Old 01-03-2001, 09:38 PM - Thread Starter
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Me again...

So I've hooked up that signal amplifier, and everything seems to work great on the tv upstairs now. Channel 81 is now Tivo throughout the house. Upstairs it is a very clear picture. Down at the source (where my tivo and modulator and amp are), high channels (like 60 and above) have picked up a bit of static. The smarthome people tell me that I should just move the amp to a place further away from that source. What's the best place for it?

Thanks as always for all the help.
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post #13 of 27 Old 01-09-2001, 04:15 PM
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Quote:
<font face="Verdana, Arial" size="2">Originally posted by mkaylor:
If you want junk go ahead and get a Channel Plus, otherwise check out http://www.cable-electronics.com/</font>

Don't you just love it when someone comes in and starts bashing things with no facts behind it. Hopefully, he won't spend much time here!



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post #14 of 27 Old 04-17-2001, 11:42 AM - Thread Starter
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Quote:
<font face="Verdana, Arial" size="2">Originally posted by Hans_Moleman:

Now back to the original topic. Norm, if you only have signal strength issues with the cable going to your upstairs tv, then put the amplifier on the splitter output that goes to that tv. With the amp located prior to the splitter in your current configuration the distortion you see on your other tv's is caused by overloading their tuners. Amplifying only the signal in need will avoid that problem.

Cheers,
Matt</font>
As always, thanks for all the help. So, for the past few months, I've been trying these suggestions, and I'm still in the same boat. I've currently got my modulator and amp at the source (my tivo). This lets me get channel 81 throughout the house fine, but at the source tv, high channels (30 & above, or so) are a bit snowy. I tried putting the amp into the garage both before and after the splitter that sends the signal throughout the house, but the result of that was either that I wouldn't get channel 81 on the upstairs tvs and/or all channels at the source tv downstairs were messed up. Any other thoughts/ideas I might be able to try?

Thanks
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post #15 of 27 Old 04-24-2001, 02:38 PM - Thread Starter
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Howdy again....anybody think of anything I haven't tried yet?

thanks!
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post #16 of 27 Old 04-27-2001, 01:26 PM
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Norm,
Draw up how you think your system is now wired (splitters, modulator, tvs). If you can't post it here, email it to me or FAX it to us at 714 996-4900 (attn Rich Foye).

We'll talk you through it, even though it is not our modulator. (BTW, the modulator is almost certainly not your problem.)

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post #17 of 27 Old 04-28-2001, 10:48 AM - Thread Starter
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Alright...here goes...I'm not a very good artist (as you can tell), but this is pretty much my set up. The 3 lone tvs are upstairs, the tv with the tivo/mod/amp/sat is downstairs.

Thanks, as always, for the help!

http://normpaperman.tripod.com/tvdiagram.GIF
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post #18 of 27 Old 04-28-2001, 02:56 PM
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Well, there's your problem. A splitter may have only a small loss from input to output (3.5dB for a 2-way, 7 for a 4-way), but will have over 20dB loss from output to output. The way you are feeding your modulated signal backwards into the 4-way insures you will have a very unbalanced system.

Good news: You probably have enough electronics to fix this. (Adding a single 2-way splitter.)
Bad news: To do this right, you will have to run another coax from the TIVO location to where the 4-way is located. Is this possible?

(I usually only check AVS once a day on work days, so it may take a bit before I answer. I'll sketch up a fix depending upon your answer.)

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post #19 of 27 Old 04-28-2001, 03:18 PM - Thread Starter
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Thanks so much for the help. As for running a cable....
I'm living in a townhouse that i'm renting. The wires, etc. were all here when we got here, and are run in the walls. The only way I'd be able (that I know of) to run another wire to the garage from the tivo would be along the baseboard (or something like that, unless running wires in the walls isn't as hard as I think it is).

Thanks again, I really do appreciate it.
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post #20 of 27 Old 04-30-2001, 08:36 AM
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OK, no new cable. Let's try to balance your system as is.
1) Below is a drawing of your system: Please verify that this is correct.
2) TIVO on channel 81 looks OK. CATV looks OK upstairs. Upper CATV channels looks snowy downstairs. Is this correct?
3) Unplug the amp. Do the upper CATV channels look better on the downstairs TV?
4) Remove the amp from the system (back to where you started to verify I am following this correctly). Is the TIVO channel (81) equally bad on all TVs?
I think this will tell me all that I need to know.

http://www.channelplus.com/files/splitter_round.gif



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post #21 of 27 Old 04-30-2001, 11:21 AM
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Well,
That's a bit of a surprise.

3) When you unplugged the amp and the downstairs TV cleared up, that means you are not seeing 'noise' as in a weak signal. This now appears to be IM (inter modulation) distortion caused by an overdrive amp. Tell me about the amp. I had been under the impression that this was an amp of ours, model DA-500. (There should be a label on the bottom.) This certainly should not be overdriven by the 25dBmV output of the Triple-play modulator.

4) This is quite surprising. The system as drawn should not be this unbalanced. Here is a possibility ... Check the splitters. If they are labeled "CATV" or "5-450MHz", this could be part of your problem.

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post #22 of 27 Old 04-30-2001, 06:50 PM - Thread Starter
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Quote:
<font face="Verdana, Arial" size="2">Originally posted by rfoye:
Well,
That's a bit of a surprise.

3) When you unplugged the amp and the downstairs TV cleared up, that means you are not seeing 'noise' as in a weak signal. This now appears to be IM (inter modulation) distortion caused by an overdrive amp. Tell me about the amp. I had been under the impression that this was an amp of ours, model DA-500. (There should be a label on the bottom.) This certainly should not be overdriven by the 25dBmV output of the Triple-play modulator.
</font>
So, just to be clear. When I completely remove the amp from the setup, the picture downstairs is fine on all channels (including 81). The picture on the upstairs tvs is fuzzy (not completely blue, as I had said earlier).

Quote:
<font face="Verdana, Arial" size="2">
4) This is quite surprising. The system as drawn should not be this unbalanced. Here is a possibility ... Check the splitters. If they are labeled "CATV" or "5-450MHz", this could be part of your problem.

</font>
The 2 splitters are:
3-way: 5-900MHz
4-way: GHS-4 1GHz

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post #23 of 27 Old 04-30-2001, 09:19 PM - Thread Starter
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Quote:
<font face="Verdana, Arial" size="2">Originally posted by rfoye:
[b]OK, no new cable. Let's try to balance your system as is.
1) Below is a drawing of your system: Please verify that this is correct.</font>
Yes, this looks right.
Quote:
<font face="Verdana, Arial" size="2">
2) TIVO on channel 81 looks OK. CATV looks OK upstairs. Upper CATV channels looks snowy downstairs. Is this correct?</font>
Yes
Quote:
<font face="Verdana, Arial" size="2">
3) Unplug the amp. Do the upper CATV channels look better on the downstairs TV?</font>
Yes
Quote:
<font face="Verdana, Arial" size="2">
4) Remove the amp from the system (back to where you started to verify I am following this correctly). Is the TIVO channel (81) equally bad on all TVs?</font>
It is equally bad on all the upstairs tv (most of the tvs display nothing (blue screen)). It is fine on the downstairs tvs.
Quote:
<font face="Verdana, Arial" size="2">
I think this will tell me all that I need to know.</font>
As always, thanks. I really appreciate it!



[This message has been edited by normpaperman (edited 04-30-2001).]
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post #24 of 27 Old 05-01-2001, 07:49 AM
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Please tell me the mfg and model of the amp.

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post #25 of 27 Old 05-01-2001, 08:56 AM - Thread Starter
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Quote:
<font face="Verdana, Arial" size="2">Originally posted by rfoye:
Please tell me the mfg and model of the amp.

</font>
Sorry...it is a channelplus DA-500

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post #26 of 27 Old 05-01-2001, 01:55 PM
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There are two things that don't add up here:
1) The triple play seems to be overdriving the DA-500, which shouldn't happen. (This behavior is also not a failure mechanism of this amp.)
2) The system sounds far more unbalanced than it should be.

I'm missing something. I need to ponder this a bit.

Norm, let's do two things:
Lets take this off line. I don't look at AVS very often, so this is dragging out. How about E-mailing me and we'll pick up from there?
Please check the diagram above. Be sure there are no other elements in the system and that the cables are connected as shown.

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post #27 of 27 Old 06-22-2001, 10:24 AM
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Just to throw out a theory, have you checked the labels of the inputs/outputs of your splitter/combiners?

I'll admit to having a similar problem until I looked at the labels and found that the configuration was something counterintuitive like this...

+------+
out-+......+--in
|......|
|......+- out
+------+


[This message has been edited by jonka (edited 06-22-2001).]
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