# Attenuator questions



## TJStaar (Aug 1, 2006)

Hi,

I read that using an attenuator can help with multipath problems with OTA reception. I went on e-bay and found several. One that I saw that looked great was an adjustable 20db model. But I also saw 3db, 6db, 10db and others.

My question is what is the difference? Is it just the signal strength and the db rating is the amount that you are lessening the signal by? Or is there a correlation between the db rating and certain frequencies?

The adjustable one sounds good because I don't know how much of an effect the multipath is causing, and I can play with it. Any help would be appreciated.

Todd


----------



## sattec (May 28, 2004)

need alot more info to really help you but.....if you split out the vhf from uhf, then used an antenuator, you could, somewhat balance the two bands and put them back together and send them to the tv or whatever.

yes, a 3 db pad will knock all freqs down 3db

the 20 adustable pad might be worth a shot but I still have alot questions, like when did you last tune the off air antenna? 

I think you want an antenuator with adjustable slope control, look for an mx-7 or an mx-4 on e-bay. It's a "antenuator/mixer" for off air. 

wish I had the answer but every situation is different....GL


----------



## TJStaar (Aug 1, 2006)

Thanks, that helps.

The main problem is with my OTA reception. I'm using an indoor antenna, which is usually great. I consistently get 80-90 strength readings. Then every so often I will get a situation where the signal won't lock, and the meter reading is jumping all over the place which causes pixelation and freezing. It will jump between 0-80. This happened on my CBS station last weekend (for the Super Bowl of course), and then that cleared up and the ABC station started. I read on one of the forums that that is usually a symptom of multipath interference and that an attenuator usually helped that.

I also read that the tuners in the HR 10-250's are especially sensitive to multipath. Last Wed. watching Lost, the signal in the 10-250 was jumping around, but the tuner in my TV was steady at 80-85. I watched it fine, but couldn't record.

I think an attic or outdoor antenna would be overkill even if I could get past the WAF. I'm just trying anything I can to maximize my signal on the indoor antenna. Any suggestions and/or help is greatly appreciated.

Todd


----------



## kenglish (Oct 2, 2004)

An attic or outdoor antenna would be best. You really need to get the antenna up above the movement of people and pets, as well as get it up higher, where the signals are usually stronger.

The only way an attenuator will help multipath is, by adding some "buffering" of the reflections in an antenna or tuner, that has a bad "return loss". That's when the impedence of the antenna or tuner input is not a good match to the cable, so it "bounces" signals back down the line. 

Sometimes, also, if your signal strength is already marginal, an attenuator will lower the entire signal....including the reflections.....to the point that the reflections are masked by noise. It's like turning down your radio until the interference on it is masked by the noise from your air conditioner....still there, but not as noticeable. But, that can create it's own set of problems.


----------



## Jim5506 (Jun 7, 2004)

An indoor antenna will always be susceptible to multipath because the signals bounce off anything metal or anything with high water content, even you. Attic is better than indoors, out side on the roof is best.

An attenuator reduces the whole signal and doubtful if it would help with multipath.

Best cure for multipath is better (more directional) antenna or move antenna to better area.


----------



## TJStaar (Aug 1, 2006)

Thanks for the help.

Todd


----------

