[mythtv-users] Antenna attenuator question

backuppc at sundquist.imapmail.org backuppc at sundquist.imapmail.org
Mon Jun 30 13:03:18 UTC 2008

Thanks for all the previous help in setting up my antenna (e.g.

Things have been working great.  I ended up using a single CM 4221
rather than my Radio Shack one because Solid Signal was having a special
the same time I bought a CM 7775 preamp, which I needed after moving the
antenna to the roof (and had a longer cable run).  I used just one
antenna after pricing out what it would cost to do the grounding
correctly.  After the pre-amp, I split the cable three-ways into a
pcHDTV5500 and a HDHR.  I've got the antenna aimed at the further
antennas about 30 miles away (FOX, PBS, etc.), with old big 3 networks
closer by behind the back of the antenna.

Here's the problem:  NBC, which is the closest antenna at about 5 miles,
sometimes comes in too strong despite being "behind" the antenna.  The
noise is apparently getting amplified above the signal because when the
pixelation starts to occur, if I go downstairs to the preamp and unplug
it, the station comes in fine (but then none of the other stations come
in at all).  Other days (like last night's Olympic Swim trials) I need
the preamp to get the signal (almost missed that program; family would
have killed me!).

I could fiddle with the aiming to try to get NBC in one of the
poor-reception nodes out the back of the antenna
(http://www.hdtvprimer.com/ANTENNAS/cm4221.html), but since the
reception is so variable anyway, I'd have to be up there all day
checking signals, and then weather would change.

So I guess I need an antenuator.  I am looking at this one:
http://www.solidsignal.com/prod_display.asp?prod=TA-8700   One question
first.  The literature says this gets installed "between the amplifier
and the TV" (replace "TV" with "mythbox" ;-).  If this is the case,
wouldn't the noise already be amplified too high?  If then, how would it

Possible answer (let me know if this is right): I suppose both signal
and noise are amplified but the tuner clips the signal as it comes in,
so the attenuator reduces both the signal and noise amplitude, so that
the signal isn't so clipped.  Correct?

I realize that antenna set up is an art more than a science (like this
guy: http://www.hdtvoice.com/voice/archive/index.php/t-21117.html) and I
don't want to end up with even more stuff I got that I ended up not
using, so any help before I place my order is appreciated.

If this attenuator is the ticket, hopefully I can find a magic setting
that will balance the strong and weak signals.

Thanks in advance.


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