Originally Posted by PCTools
I disagree agree about overloading as my existing rig, did not have any issues with channel overloading with the 9032 and monster VIP-307 at 50' in the air.
I understand. I can only go by your report, which is only a computer simulation, and the CM specs for the new 7777. It is possible that the signals are weaker than predicted by the report because of terrain interference.
WUPW -31.4 dBm
Max input of new 7777 = 15 dBmV = -34 dBm; overload
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.
WUPW -31.4 dBm + estimated ant gain 10dB = -21.4 dBm, preamp overload of 12.6 dB
Even with the 7778 and a 91XG there is the possibility of tuner overload:
7778 Max input level 34 dBmV = -15 dBm
WUPW -31.4 dBm + 14 dBd 91XG = -17.4 dBm; preamp OK
WUPW -31.4 dBm + 14 dBd 91XG + 16 dB preamp gain = -1.4 dBm; tuner overload
ATSC Recommended Practice:
Receiver Performance Guidelines
Document A/74:2010, 7 April 2010
RECEIVER PERFORMANCE GUIDELINES
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.
5.2 Multi-Signal Overload
The DTV receiver should accommodate more than one undesired, high-level, NSTC or DTV signal 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.
The new 7777 not only has only one input, but has a gain of 30 dB and is more easily overloaded. There is such a thing as too much gain; it is only suitable for locations where ALL the signals are weak. CM had to add the warning to the description because they had so many returns from people who should have ordered the 7778 instead. You only need enough gain to offset distribution losses.
I would rather warn you of possible overload than to have you order the wrong preamp and wonder why it doesn't help.