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Old 22-Jan-2017, 6:41 PM   #9
Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,516
That might work, but the VHF port of the second UVSJ would need to be power passive for the preamp. The Radio Shack and Antennas Direct UVSJs are power passive on the UHF port, not the VHF port.

       UHF> Jumper> UHF 
        /             \
7698> UVSJ           UVSJ> coax> grounding> power> tuner
        \             /            block   inserter
       VHF> Preamp> VHF
Another possible solution is to attenuate the UHF and amplify both. The attenuator value would be selected by trial and error. Too much attenuation would make WXEL 27 too weak; not enough attenuation would cause overload from 16 and 34. I suggest 15 dB as a starting point to make it as weak as the VHF channels before amplification.

      UHF> Attenuator> UHF 
       /                \
7698> UVSJ            UVSJ> preamp> coax> grounding> power> attenuator> tuner
       \                /                  block    inserter
      VHF> FM Filter > VHF
You might also need an FM filter between the VHF port of the first UVSJ and the VHF port of the second UVSJ. You have a strong FM signal coming from the south.

I suggest a HLSJ, High and Line ports, as an FM filter and an Antennas Direct Juice preamp because it is resistant to overload.

You might need some attenuation after the preamp power inserter to prevent tuner overload. The signal dynamic range between CH 16 and CH 12 will be about 36 dB, for a required SFDR (Spurious-Free Dynamic Range) of 52 dB after adding the minimum required SNR of 16 dB for CH 12.

Attached Images
File Type: jpg SFDRdiagramJ3_1.jpg (144.7 KB, 1777 views)
File Type: jpg HLSJ as FM Trap.jpg (71.7 KB, 246 views)
If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 23-Jan-2017 at 2:34 AM.
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