HD8200U loses all my channels

[tsndrf]

I just had a HD8200U antennna installed. Almost every night between 4:15 -6pm I slowly lose all my channels. They are all back, clear as a bell, by morning. This happens almost every night. The guy who installed our antenna has been back several times, but can find nothing wrong. We have troubleshot everything in our house as interference, but it has to be something outside our house. What can we do?

[TomV]

What is your zip code so we can know where your house is relative to the TV antenna farms.

Do you have any amplifiers in the distribution system?

Are you near any airports, manufacturing or office facilities? Neighbors with shortwave radios?

What troubleshooting techniques are you using to determine interference from within the house?

So the problem is mostly starting in the late PM and not clearing up until daybreak?