Question: Sending antenna signal to multiple TVs

mahohmei

DTVUSA Jr. Member
#1
I have purchased a Stellar Labs 30-2430 bowtie antenna, installed it in the attic, and it now works perfectly in the living room with no amplifiers at all. The total RG6 run is about 100': 70' from the antenna to the structured wiring box, and another 30' from the SWB to the living room. No splitters; the cables are just joined by a coupler in the SWB.

I'd now like to split the signal between three TVs. I ran the antenna into a four-way splitter and out to three TVs, and I put a 75-ohm termination cap on the fourth output. The signal was extremely weak and "pixelated". I then installed, right before the splitter, a Stellar Labs 30-2167 25 dB antenna amplifier (25dB RF Signal Amplifier - 50~860MHz | 30-2167 (302167) | Distributed By MCM). With this in place, all the TVs got no signal whatsoever.

What am I doing wrong?

Thanks!
 
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#2
It would seem to me that that the little distribution amplifier you purchased is dead. Near by strong TV, FM, or other out of band signals could be driving the cheap amplifier into overload. The splitter could be bad, but keep in mind adding a 4 way splitter is about like adding an extra 100' of coax. Have you tested the individual runs of coax with out the splitter to see if they are alright. If your using old cable company coax runs that could be a big part of the problem they had plenty of signal to work with, and were not concerned about coax loss. From what you have told us a distribution amplifier is probably the right choice. The Channel Master CM 3414 has a pretty good reputation.
Channel Master CM3414 Distribution Amplifier (CM-3414) from Solid Signal
When trying build a well balanced signal distribution system with long coax runs of different lengths, signals of different levels, unknown out of band interference, to be delivered to receivers of varying quality. It's amazing when we sometimes get it right, and everything works the first try.
Steve
 

MrPogi

Moderator, , Webmaster of Cache Free TV
Staff member
#3
I agree that it's probably the amp, and the Channel Master CM3414 would be a good choice. I would use a pre amp myself, for the simple reason that it doesn't amplify any noise introduced in the 100 feet of cable between the antenna and the amp. The only reason I might prefer a distribution amp is that its easier to install and easy to remove from the system if it goes bad or the power goes out.
 

mahohmei

DTVUSA Jr. Member
#4
What's the definition of a preamplifier? Is it anything that takes its power in from coax so it can be placed right on the antenna to avoid having to install an AC receptacle next to the antenna? I have a 15 dB two-piece amplifier (injector plus amplifier) from RadioShack, and I can always stick that in the attic.

That having been said, it would be nice if I could power everything from the structured wiring box. It has a UPS, so surge protection and power failures are taken care of...not that it would matter with no UPSs on my TVs or TiVo. :)

Playing around with the setup isn't hard at all. The antenna is right next to the attic hatch, there's a plywood floor up there to work on, and if I *do* need a receptacle next to the antenna, I can install one by just tapping the garage door opener receptacle.
 
#5
From Wikipedia.
"A preamplifier (preamp) is an electronic amplifier that prepares a small electrical signal for further amplification or processing. A preamplifier is often placed close to the sensor to reduce the effects of noise and interference."
In TV antenna applications the low voltage power required by the preamplifier is most often sent via the coax. An unpowered amplifier in line will block signal. It is important that coax run between the power inserter and preamp is not interrupted by anything that blocks power.
Try the two piece Radio Shack amplifier. It might do the job.
MrPogi covered the reasons I didn't suggest a preamp in my first reply. Keep in mind the primary purpose of an amplifier is to overcome feed line, and distribution loss.
Steve
 

mahohmei

DTVUSA Jr. Member
#6
The RadioShack two-piece amplifier did *not* work; couldn't get a signal at all. I put the amplifier half right next to the antenna and the injector half in the SWB before the TV. This did not work with a 4-way splitter, nor did it work on a direct run to one TV.

I'm going to go ahead and get the ChannelMaster CM3414 distribution amplifier. I don't really think a preamplifier is in order, sine all the channels come in perfectly with no amplification whatsoever...as long as it's a single cable run. It could be that the RadioShack and Stellar Labs amplifiers I had tried before were just relative pieces of junk.

For what it's worth, the cable runs are all RG-6 with compression connectors, all of which my wife and I ran ourselves--and it's all in tight shape and all works.
 

MrPogi

Moderator, , Webmaster of Cache Free TV
Staff member
#7
I put the amplifier half right next to the antenna and the injector half in the SWB before the TV.
What is a "SWB"? The only thing that should be between the amp and the power injector is COAX. No switches, splitters or anything.
 

mahohmei

DTVUSA Jr. Member
#9
Sorry...SWB = structured wiring box. Big cabinet in a closet where all house wiring comes in from all wallplates and the antenna. Central location to place any splitters, couplers, surge protectors, Ethernet switches, etc.
 
#10
While I know that two dead junk amplifiers is a possibility. If you haven't already done it I would be testing cables for continuity, and shorts. I've learned from experience to test continuity of cables regardless of how good the cables appear to be built. I've seen some real strange reception results with digital signals caused by bad cables. Even faulty connectors always seem to work at first. Then they start to cause problems in a manner that seems unrelated to the connectors.
Steve
 

MrPogi

Moderator, , Webmaster of Cache Free TV
Staff member
#11
Sorry...SWB = structured wiring box. Big cabinet in a closet where all house wiring comes in from all wallplates and the antenna. Central location to place any splitters, couplers, surge protectors, Ethernet switches, etc.
Your power injector should be before the box, not after. There is a good possibility there are splitters in there.
 

mahohmei

DTVUSA Jr. Member
#12
The ChannelMaster CM3414 did the job perfectly, with one hitch. It turns out that the TiVo Premiere is *very* persnickety about signal strength.

Straight in from the antenna, it worked.
Going through a passive splitter (7.5 dB loss), it didn't work.
Going through a distribution amplifier (8 dB gain), it didn't work, but the Samsung and LG TVs in our house *did* work.
The solution? I ran the output from the amplifier through the passive splitter, padding it by 7.5 dB before going to the TiVo--now everything works perfectly.

I'm going to just buy a signal pad to reduce the clutter in my headend cabinet...
 

MrPogi

Moderator, , Webmaster of Cache Free TV
Staff member
#13
The problem with the TiVo is understandable. TiVo has not aimed primarily at the OTA TV market, so what they designed is built for stronger, more stable signals. For an OTA DVR, I would prefer a Channel Master DVR+ or a Tablo DVR over a TiVo product. And the new TiVo Roamio seems like a bargain until you find out that the program guide costs $14.99 a month, with no annual discounts or "one time payment" option available.
 

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