[mythtv-users] Antenna amplifier

Yan Seiner yan at seiner.com
Tue Aug 5 04:01:33 UTC 2008


Brian Wood wrote:
> Yan Seiner wrote:
>   
>> More on the Olympics.  NBC is broadcasting it.  I never watch NBC.  It 
>> comes in with the weakest signal - my pcHDTV won't lock in on it.  (Now 
>> I find out.)
>>
>> So two alternatives: 
>>
>> 1.  Get up on the roof and fsck with the antennas to the great amusement 
>> of my family and neighbors.
>>     
>
> Certainly the cheaper approach.
>
>   
>> 2.  Get a 2 way amplified splitter.  About 9 to 12 DB should be plenty.  
>> Any suggestions on model/brand/suitability?
>>     
>
> Depends, you may just be boosting the noise floor by 9 - 12 db.
>
> To do it properly you need to know where the xmtr is, what it's ERP and
> countour is, your antenna specs, your height, losses in your signal path
> etc. etc.
>
> An antenna in good condition, properly aimed and mounted is a good
> start. More basically - can your neighbors get a usable signal on NBC
> from an antenna? If not, you are not likely to do much better.
>
> I've read that capture cards require more signal than TV sets, but this
> doesn't make sense to me as the card makers are almost certainly using
> off-the-shelf tuners. If you can get +10dbmv. great, even zero should be
> watchable.
>   

Well, here's what's really bizarre.

I have two highly directional antennas at 90 degrees.  They're far 
enough apart where interference is not an issue.  They go to an 
unamplified splitter, there to an old Blonder-Tongue 6DB amp and 4 way 
splitter, and then to the TV and the myth backend.

The TV has a passive splitter that splits the signals to the analog and 
digital antenna inputs.  The TV shows a consistent signal strength 
across all channels of about 60% (meaningless except that the signal 
strength is approximately the same).  Myth gets a straight run from the 
B-T amp to a pcHDTV card.  That card *also* shows a consistent signal 
strength across all channels of about 60% - except NBC on channel 16 
which comes in at a dismal 7 to 13%.  Can anyone take a shot at 
explaining this?

Channel 16 is the closest station and has the strongest signal, so the 
issue could be overfeeding, but I get dismal results with a straight run 
to the pcHDTV with no splitters or amps....

--Yan

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