Welcome to the forum, Marc:
It sounds like without the preamp you don't have enough gain, and with it you have too much. The 7777 probably wasn't the best choice; the 7778 would have been better. To quote Channel Master:
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The Titan 2 High Gain Preamplifier is recommended for professional installers only. Due to the high gain output of this product, it can result in over amplification if not used in the appropriate scenario. Over amplification can cause issues with the television tuner’s ability to receive and display some or all channels.
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You are probably having problems with preamp or tuner overload.
Your strongest UHF signal CIII has a Noise Margin of 51.7 dB. If you add the gain of the C2 of 10 dB, that brings you up to 61.7 dB, which the 7777 doesn't like.
https://www.antennasdirect.com/cmss_...uctions%20.pdf
Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html
If you then add the 7777 gain of 30 dB, that brings you up to NM 91.7 dB, which is way too much for the tuner.
In terms of signal Pwr dBm as listed on your tvfooj report, CIII is -39.1 dBm. Add the antenna gain of 10 dB brings you up to -29.1 dBm. Add the preamp gain of 30 dB brings you up to +0.9 dBm. Tuners are not expected to handle signals stronger than -5 dBm for a single signal or stronger than -8 dBm for more than one.
ATSC Recommended Practice:
Receiver Performance Guidelines
Document A/74:2010, 7 April 2010
RECEIVER PERFORMANCE GUIDELINES
5.1 Sensitivity
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A DTV receiver should achieve a bit error rate in the transport stream of no worse than 3x10E-6 (i.e., the FCC Advisory Committee on Advanced Television Service, ACATS, Threshold of Visibility, TOV) for input RF signal levels directly to the tuner from –83 dBm to –5 dBm for both the VHF and UHF bands.
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5.2 Multi-Signal Overload
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The DTV receiver should accommodate more than one undesired, high-level, NSTC or DTVsignal at its input, received from transmission facilities that are in close proximity to one another. For purposes of this guideline, it should be assumed that multiple signals, each approaching –8 dBm, will exist at the input of the receiver.
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As an inexpensive test I suggest you add an attenuator between the antenna and the preamp input. It might be possible to find a happy medium.
https://www.antennasdirect.com/store...ttenuator.html
http://mjsales.net/collections/atten...ant=1083705673
•Attenuation values 1, 3, 6, 8, 10, 12, 16, 20dB (FAM)
click on 1 dB to see other values, up and down arrows are faint
http://www.3starinc.com/drop_in-line_attenuator.html
http://home-automation.smarthome.com...=&w=attenuator
Try a combination of the variable attenuator and fixed attenuators; you might need more than 20 dB. Replace that combo with equivalent fixed values.
If that doesn't work, try a more directional UHF antenna; the C2 beamwidth is very wide. Consider the DB4E.
If that doesn't work, try a separate DB4E with its own preamp and a Tin Lee custom single channel bandpass filter for real channel 35.
http://www.tinlee.com/index.php
http://www.tinlee.com/catv_filters.php?active=1
http://www.tinlee.com/bandpass_filters.php?active=1
Talk to one of their engineers, and email your tvfool report to him.
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I have the antenna pointed as close as I can to 116 degrees.
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116 degrees true, 126 magnetic.
The coax shield should be grounded with a grounding block that is connected to the house electrical system ground with 10 gauge copper wire for electrical safety
and to reject interference. For further compliance with the electrical code (NEC in the US), the mast should also be grounded in a similar manner to drain any buildup of static charge, but the system will not survive a direct strike.
The data is probably not up to date, but I see some strong FM signals that might interfere with TV reception. An FM filter is needed; see attachment 2.