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Old 12-Apr-2016, 1:30 AM   #19
rabbit73
Retired A/V Tech
 
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,747
I did a tvfool report using your exact coordinates at 25 feet:
http://www.tvfool.com/?option=com_wr...513446ab1b8443

The NM difference is now only
KCTV 72.4 dB - KCKS 17.4 dB = 55 dB

55 dB - 33 dB adjacent channel allowed = 22 dB

22 dB - 20 dB from antenna pattern = only 2 dB away from spec

Raising the antenna makes the KCKS NM much better, with little change in the KCTV NM, because the KCKS signal is coming in at a very low angle and skimming the trees and terrain. You must get the antenna as high as possible to clear the path from the west.






Using a preamp is a last resort. The AD Juice and the CM3410 are more resistant to overload than the RCA TVPRAMP1R; see attachment 3.

RCA TVPRAMP1R max input UHF = -35.5 dBm
Antennas Direct Juice max input UHF = -21.3 dBm

RCA TVPRAMP1R SFDR UHF = 67.3 dB
Antennas Direct Juice SFDR UHF = 81.7 dB

SFDR is the difference between the weakest and strongest signal that the preamp can handle.

Even if the preamp can avoid overload, the tuner might be overloaded by your strongest signals. KCPT has a NM of 73.7 dB even before adding antenna and preamp gain. The preamp would improve the system noise figure, but you would need to add an attenuator after the power inserter to prevent tuner overload.



Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html
Attached Images
File Type: jpg traker1001TVFtrees2.JPG (100.0 KB, 1563 views)
File Type: jpg traker1001TVFtrees_1.jpg (161.0 KB, 1670 views)
File Type: gif Peamp.gif (82.7 KB, 599 views)
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Last edited by rabbit73; 12-Apr-2016 at 11:39 AM.
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