For issues with bad range or bad video quality, the following causes are possible:
1. Interference or a problem with position. Ensure that your transmitter and receiver are free of obstacles to the best of your ability and make sure the devices are mounted upright such that the internal antennas point up. Having the devices up higher is also beneficial to improving range. Additionally, using a Sony PsF video format can have a negative effect on video quality.
2. Broken antenna connectors. If your transmitter or receiver has a broken antenna connector anywhere, you would see significantly diminished range and/or video quality.
3. An issue with the wireless board. If all antenna connectors are properly intact and the device is in a good environment, bad range may be experienced if the wireless module is not performing as it should.
For hardware-related causes like cause 2 and 3, please contact email@example.com to discuss repair options.