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Old 11-Sep-2015, 7:19 PM   #7
Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,724
Thanks for the TVFOOL report. That puts you, as your report says, further out from the center of Topeka in Tecumseh near Watson. Your Topeka signals are about 5 dB weaker than my first estimate and so are your KC signals, with about 50 dB difference between them.

Thanks for the antenna info. That GE antenna is good for strong signal areas, but doesn't have much gain for the weaker KC signals.

I should be able to safely put up a temporary mast without the grounding to test for reception as long as it is clear, hadnt I ? I WON'T leave it without proper grounding.
As far as avoiding storms, that's good. But as far as electrical safety goes, remember that the coax from the antenna is connected to AC operated equipment. All AC operated equipment has leakage current even when it is operating properly. Just because you can't feel it doesn't mean it isn't there. If the equipment has a 3-wire power cord that is connected to a properly wired 3-wire receptacle, it will drain the leakge current to ground, but many TVs only have a 2-wire cord.

If the equipment became defective, there might be a shock hazard. If you feel a tingle from the coax shield, you must ground the coax with a grounding block.

When you make the test with the GE antenna outside with the antenna aimed at Topeka, the local signals will be stronger, but probably will not overload the tuner. When you aim the antenna toward KC the antenna might do a little better than inside and still receive the Topeka signals.

The problem is that you need an antenna with more gain for KC (which would be more directional), and maybe a preamp too, but a preamp might be overloaded by the Topeka signals. Maybe you will be able to find a happy medium, but I think the best reception would be with two antennas and a switch.

KTWU has a Noise Margin of 62.6 dB even before adding antenna gain or preamp gain, which puts it in the Possible Overload category. KSHB has a NM of 6.1 dB, Weak.

Interpreting Noise Margin in the TV Fool Report
If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 11-Sep-2015 at 8:07 PM.
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