811 OTA Problem

[Grandpa J]

This may have been cover before, but I can not find it.

I live outside of the main LA area and get my local HD/Digital channels OTA using a large antenna with a amp. I do not get analog channels OTA. The 811 is able to lock on and get all the LA Digital channels. However as of late the NBC channel (4/36) will work sometimes but freguently it will not work. The signal strength show 81 to 83 (same as when it does work) but the screen will go blank and the "error" screen comes on. I tried a work around by going to "add digital" (menu 6-1-5) and resetting NBC - again the signal shows 81 to 83 - but "not locked", yet the channel listing will show channel 4 (actual 4-01). Some other channels that always work have signal strenghts as low as 72.

Is this a "known" 811 problem?

 

[GaryPen]

Try removing the amp. The 811's OTA tuner is flaky, especually when it comes to multipath. The amp may be increasing the multipath signals, thus confusing the 811. That is why you get a good signal level, but can't lock on.

 

[Grandpa J]

Thank you GaryPen

As I live on the very fringe of the LA signals I can not get a acceptable signal without an amp. Not really sure what multipath is. Last night NBC was working with a signal strenght of 76% so go figure.

Thanks again

 

[GaryPen]

Multipath is a fancy word for reflected signals, the kind of signals that cause ghosting on analog OTA reception. The 811 handles multipath like crap. Signal amps boost multipath. There's the rub.

One forum member also puts an attenuator in line after the amp. It sounds like it would defeat the purpose of the amp. But, according to him, it provides the right combination for a good strong, but multipath-free, signal. Maybe the attenuator is adjustable, and he adjusts it according to channel? I don't know.

 

[Grandpa J]

Thanks again

 

[Bobhend]

Amps and attenuators

I have run a Radio Shack attenuator in front of a CM 7777 amp. Only thing to watch out for, this attenuator's knob is labeled MIN and MAX but they mean the ATTENUATION [ idiots !] MIN results in full power signal passing thru to the amp, MAX is I think 20 db reduction in strength.

 

[SimpleSimon]

The label makes perfect sense to me. It's an attenuator. Min means minimum attenuation. Max is maximum attenuation.

 

[GaryPen]

Yes, it doesn't not make perfect sense.

 

[SimpleSimon]

Eggzaklee.