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Old 22-Oct-2014, 11:01 PM   #1
ronenbar
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Join Date: Sep 2014
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Reception in Redmond WA

Hi,

Here is the link to the signal analysis report.

http://www.tvfool.com/?option=com_wr...d2439614432755


The antenna is CM4228HD on a 10 ft mast attached to the chimney. Antenna height is roughly 30ft.

The Antenna points to 240 relative to magnetic north. I have a rotator so this is easily adjustable.

The Antenna is connected to a CM7777 (high gain) amplifier.

The output of the amplifier goes to a distribution amplifier (the one Comcast installed in my house prior to moving to OTA).

The TV is Samsung LN46C650.


The TV reports a singal level (SNR) on its self diagnosis menu of ~16db for the stations transmitting from where the antenna is pointing too. I get mostly one bar sometimes two. I do get interruptions from time to time.

For the channels that interest me:
I get KIRO-TV on channel 51 very strong (25db, 7 bars) even though the antenna is not pointing at it.
I get channels 39, 38, 31 at ~16db - 1 bar
I don't get 50.
I don't get channel 48 at all.
I get channel 13 and 22 with 1-2 bars.



Questions:
Is this the best reception I can hope for or does it indicate something is wrong or can be improved with my setup?
Does this level of reception basically mean I should give up on OTA at this location because it is not stable enough (i.e. don't go and buy a OTA DVR...switch back to cable).

Thanks,
Ronen
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Old 23-Oct-2014, 12:11 AM   #2
ADTech
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1. Remove the pre-amp.
2. See step 1.

There is absolutely no need for high-gain amp. Probably no need for the DA either, but it likely won't harm reception.

For initial setup, run a single temporary coax cable straight from the antenna to the TV and test reception. If that works, build one piece at a time back until you have the system put back together without breaking anything.
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Old 23-Oct-2014, 12:20 AM   #3
ronenbar
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Tnx.

One point that I forgot to mention. This same setup was hooked with a CM7778 (medium gain) before and then the reception was worse. A few channels from the 240 direction appeared only after replacing the medium gain with a high gain amplifier.

So, isn't removing the pre-amplifier altogether going to make things much worse?
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Old 23-Oct-2014, 1:33 AM   #4
ADTech
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How big is the hill you're aimed into (how much higher than the antenna)?

Is the antenna aimed point-blank into a forest?
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Old 23-Oct-2014, 3:07 AM   #5
ronenbar
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Looking at topographic maps the height of the antenna is ~265 ft. on the line of sight between the house and the transmitting antenna the land slopes from 236ft to around 500ft over 1.5 miles.

Attached is the rough elevation graph (ft on Y axis, miles from house on X axes).
Attached Images
File Type: png elevation_graph.png (15.0 KB, 513 views)
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Old 23-Oct-2014, 3:16 AM   #6
ronenbar
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And the transmitting tower base for the stations that I don't receive well is at ~460ft (not including the tower height which is huge...).
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