Careful, those specs are for the OLD preamps, not the new ones which say for both
Quote:
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Noise figure typically less than 2dB
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http://www.channelmaster.com/TV_Ante..._p/cm-7777.htm
http://www.channelmaster.com/TV_Ante..._p/cm-7778.htm
and I have not see any independent verification of those figures
New 7777
Gain 30dB
Max input level 15 dBmV, which is equal to -34 dBm using a conversion factor of 49
Max output level 40 dBmV, -9 dBm
New 7778
Gain 16dB
Max input level 34 dBmV, -15 dBm
Max output level 50 dBmV, +1 dBm
Notice that the specs for the OLD 7777 said:
"Maximum input is output capability minus gain."
They fudged the figures for the new 7777:
40 dBmV minus 30 is 10 dBmV, not 15 dBmV, which is equal to -39 dBm.
The calculations go like this using Noise Margin numbers:
Your strongest signal is WRGB on real channel 6 with a NM of 26.7 dB. If you add the antenna gain of 6 dB, you are at 32.7 dB. If you then add the preamp gain of 30 dB and subtract the preamp noise figure plus distribution loss of 5 dB, you are at NM 57.7 dB. That looks OK.
Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html
Using signal strength from the Pwr (dBm) column of your tvfool report, WRGB 6 is -64.2 dBm. If you add the antenna gain of 6 dB, you are at -58.2 dBm, so that's OK for your preamp input.
However, there might be a problem if you want to use your HD8200XL TV antenna for FM, because your strongest FM signal is -36.9 dBm, which is 27.3 dB stronger than your strongest TV signal. I don't see any gain figures for the HD8200XL on FM, so plus 7 dB giving you -29.9 dBm, which is more than the rated max input of the new 7777. You would need to use the FM trap in the 7777 and a separate antenna for FM.