I need a converter box that converts ch3 analog TV to ch3 digital TV. I can not use RCA or HDMI connectors. The input and output connectors need to be "F" connectors. The box will feed a device that only takes digital TV ch3 or ch4 from an "F" connector. I am not looking for a digital to analog converter!
ATSC channel modulators take an component video or HDMI input, not RF channel 3 which can't be converted directly to digital. They are not cheap either. http/www.amazon.com/PVI-MICROMOD-Channel-Digital-Modulator/dp/B00F7SE5MO
I assume that your TV doesn't have an analog tuner built in? You won't get HD from an SD signal even if it is converted to a digital channel.