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Old 9-May-2019, 9:45 PM   #8
Tower Guy
Senior Member
Join Date: Dec 2009
Location: Delmar, NY
Posts: 1,234
The 750 MHz Low Pass Filter goes between the antenna and the combiner(splitter). The attenuator goes between the modulator and the combiner (splitter). The attenuator may need to be a bit more or less than 20 dB. Note that the modulator has a rated output of +30 dbmv. This equates to a NM in the 70 dB range for digital signals or roughly 35 dB for analog signals.

Here’s my thinking:

I agree with ADTech that the modulator is putting out signals that interfere with the off air channels. The attenuator will fix that.......BUT the OTA antenna is picking up LTE signals above 700 MHz, so they interfere with the modulator. The LPF-750 will filter out the LTE signals on channels 65-69.
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