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Variable attenuator for cable tv?

post #1 of 13
Thread Starter 
Where can I buy a variable attenuator for a cable tv set up? Thanks.
post #2 of 13
Why? How do you know the incoming signal is too "hot"?
If you suspect a signal level problem, why not contact your cable provider to resolve?
post #3 of 13
Thread Starter 
Well, some of my runs are very long and needed a booster. When some of the shorter runs come out of the booster they get the wave in the picture. The longer runs are great. After much testing this is what we have determined we need.
post #4 of 13
FWIW:

Below are a couple of possible options for attenuation/compensation:
  1. Winegard TC-200A Tilt Compensator, $10.95.
    Description: "Coaxial cable attenuates high frequencies greater than low frequencies. This problem is most severe when cascading amplifiers one after another. The signal differences are attenuated to a point where the high frequency signals are so small compared to the low frequency signals that the high frequency signals can no longer be received. The TC-200A Tilt Compensator provides a balanced signal level by compensating for 200 feet of coax cable loss and allowing all signal levels on all channels to be of equal amplitude at distant locations. Therefore, the picture quality on the higher channels will be maintained."
  2. Winegard TA-8700 Variable Attenuator, $19.85.
    A 75-Ohm attenuator for continuously variable attenuation from 1-17 dB. AC-DC passive.
post #5 of 13
Thread Starter 
Yeah, my problem is on the upper channels. The lower ones seem fine. The upper are doing the wave.
post #6 of 13
Could you just use a splitter(s) and attach the short run(s) directly to one leg and connect the amp to the other leg for the long runs?

IMO, an attenuator after an amp may resolve your issues for the short runs and alternatively cause problems for the long runs. You may wind up having to adjust the attenuator every time you watch a different TV.
post #7 of 13
How "big" of an amp did you get?

You might want to draw up a diagram of your system, then insert the approximate values of the cable losses, splitter losses, etc. Then, do a little math to see what runs are getting what amount of boost. You really want to shoot for a "zero loss" from the initial Cable TV drop, to the point where the TV sets are.

You could then use fixed attenuators (a dollar or two each, vs the $20 that variable attenuators cost) on individual lines, to balance things out. You might just have way too much amplification, though. That would cause inter-modulation distortion on the higher channels.

Look at the Channel Plus website and others, for suggestions and for tables of cable and splitter losses.
post #8 of 13
... also provide (approximate) coax cable distances from the initial drop, to first splitter and each subsequent amp/split. Also indicate each type of splitter (2 way, 3 way, etc.).

The more detailed info that you can provide will help to provide suggestions/recommendations.
post #9 of 13
I bought one sometime back from here that works for about a 0-20dB attenuation range. Before that I used an old similar Radio Shack model.

http://www.antennasdirect.com/attenuator.html

Some years back I installed a +15dB fixed lownoise bi-directional cable TV amplifier where my main coax line comes in the garage prior to splitters. Then on one TV I needed some attenuation so I used the variable attenuator for testing to determine the approximate value I needed. Then I got some fixed attenuators and used one of those instead for the final setup. I just keep the variable unit around for testing if I need an attenuator somewhere now.
post #10 of 13
WAJO, I installed a pre-amplifier on my antenna because a couple of stations (ABC & FOX) were cutting in and out. My pre-amp, from Antennas Direct brought in the weak channels exceptionally well but my PBS channel won't hold the signal. Before the pre-amp it was my strongest station with 80%. Now it is very weak with less than 10 percent. I tried looking for an adjustable attenuator and saw your post. I'm not sure the attenuator will solve my problem and probably need an adjustable one since I couldn't guess what value of RF loss I would need.

Since your post was a couple of years ago I thought I would ask to see if you know of a better product or have any other thoughts on solving this. Your posts on the Maggie were so helpful in setting mine up and I haven't had one issue with it.
post #11 of 13
Quote:
Originally Posted by REJI View Post

WAJO, I installed a pre-amplifier on my antenna because a couple of stations (ABC & FOX) were cutting in and out. My pre-amp, from Antennas Direct brought in the weak channels exceptionally well but my PBS channel won't hold the signal. Before the pre-amp it was my strongest station with 80%. Now it is very weak with less than 10 percent. I tried looking for an adjustable attenuator and saw your post. I'm not sure the attenuator will solve my problem and probably need an adjustable one since I couldn't guess what value of RF loss I would need.

Since your post was a couple of years ago I thought I would ask to see if you know of a better product or have any other thoughts on solving this. Your posts on the Maggie were so helpful in setting mine up and I haven't had one issue with it.

 

The two products I wrote about way back then are still available, but I'm not sure which, if any, you might need. Here's what I posted before with the same links where you can read a little on them and decide if they sound like they might help your situation.

 

  1. Winegard TC-200A Tilt Compensator, $10.95.
    Description: "Coaxial cable attenuates high frequencies greater than low frequencies. This problem is most severe when cascading amplifiers one after another. The signal differences are attenuated to a point where the high frequency signals are so small compared to the low frequency signals that the high frequency signals can no longer be received. The TC-200A Tilt Compensator provides a balanced signal level by compensating for 200 feet of coax cable loss and allowing all signal levels on all channels to be of equal amplitude at distant locations. Therefore, the picture quality on the higher channels will be maintained."
  2. Variable Attenuator, $11.99.
    A 75-Ohm attenuator for continuously variable attenuation up to 20 dB.
post #12 of 13
I have a similar situation I'd like to get some input on. I have security cameras (CCTV) and I'm trying to connect to my TV's that are using an (outside TV antenna) OTA. I've been successful in getting everything working with a SV-2G splitter (5/1000 MHz) installed on the OTA feed prior to a Rat Shack Hi-gain Adjustable Antenna Amplifier. The other leg of the splitter is where I connected the CCTV feed. This configuration yields good OTA channels and clarity, but the CCTV is very snowy. When I installed a Attenuator on the OTA feed (prior to the splitter) it cleaned up the CCTV feed, but then lost about 20% of my OTA channels (PBS & FOX), probably due to the reduced signal input after the Attenuator. I tried a 5-2150 MHz splitter in place of the SV-2G, but it was worse. I also tried adjusting the Hi-gain amplifier, but again, no change. Is there a different type of splitter or Attenuator that I might try to regain the lost TV channels without affecting the quality of the CCTV picture? Diagram below. Thanks for any ideas!

TVAntennaConnections.doc 24k .doc file
post #13 of 13
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