Frequency Attenuation

[twolf58]

I have identified what I suspect to be an instance where certain local OTA frequencies are delivering too much gain and overpowering one of my ATSC tuners. I get all of the available channels fine on the TV but when tuning through a STB, two known excellent signals do not display.

I would just attenuate the line going in but then I will loose a few fringe channels with weaker signals.

Are there any frequency specific attenuators / filters that can be used for OTA?

 

[brantlew]

Are there any frequency specific attenuators / filters that can be used for OTA?

I'm not aware of any notch attenuators?? You might be able to construct something like it if you use a splitter, an attenuator, a notch filter and a combiner. The idea being that you would split the signal and attenuate one side and then recombine just the notch frequencies back into the mainline. This is just a guess though. All that hardware might reduce your weak frequencies too much to make it worth it. Does anybody know if this would work or a better way to make a notch attenuator?

 

[nsaspook]

I have identified what I suspect to be an instance where certain local OTA frequencies are delivering too much gain and overpowering one of my ATSC tuners. I get all of the available channels fine on the TV but when tuning through a STB, two known excellent signals do not display.

I would just attenuate the line going in but then I will loose a few fringe channels with weaker signals.

Are there any frequency specific attenuators / filters that can be used for OTA?

Blonder Tongue makes a trap that tunes the TV/FM bands, but it's not cheap.
http://www.blondertongue.com/headend/mwt.pdf
Product Search | Solid Signal

http://www.blondertongue.com/headend/Headend.pdf

 

[twolf58]

Thanks

Thanks for the tip, and I see you weren't kidding about them being not cheap.

I have read about how these digital OTA channels can do some strange stuff like this and how interference from adjacent frequencies might also mess things up.

Since my TV gets the stations just fine I may wait a bit do some more testing to see if too strong a signal is really the culprit. Its kinda sad though since the problem frequencies include the local FOX channel and the wife really wanted the DVR for American Idol.

 

[autiger62]

Maybe you can find what you need here ... They have several notch filters and attenuators.

RF Distribution, Amplifiers, Modulators, Combiners, Splitters, Video Distribution

 

[twolf58]

Thanks for the link…I also found them in the Cannel Plus brand here for a reasonable price http://www.spytown.com/nf-470.htmlhttp://www.spytown.com/nf-470.htmlhttp://www.spytown.com/nf-470.htmlhttp://www.spytown.com/nf-470.html as well a a high range price here http://www.smarthome.com/7822f.html

This still will end up costing a bit so more investigation may be necessary.

My affected channels are UHF 21 (MyNetwork), 22 (CW), and 26 (FOX) so it looks like I will need to split the line…cascade 2 Notch filters on one leg…attenuate the other leg…and recombine.

I think I will go up and tweak the antenna to see if I can find an interference problem since I have it mounted in the garage rafters…take out the amp…and generally see if I can get the receiver to find them anyway I can first…I would like to rule out the tuner before purchasing a fix.

Maybe it is defective or the TV just has a much higher quality tuner in it, they are both fed from the same line and split within a couple ft and I’ve tried both legs from the splitter and without it…same results.

 

[oljim]

Put the antenna outside remove the amp, bet your problem will go away