Well, you’ve tried everything. You have been unsuccessful in resolving your noise situation. There are a few options to consider; all these are taken from real world scenarios:
- Try out digital modes. Due to their narrow bandwidth and protocols they are often less impacted by a poor signal to noise ratio
- Consider taking your hobby mobile or portable. Try out SOTA, Parks ‘n Peaks or you own hybrid version
Peter Parker VK3YE for portable operation inspiration
- Investigate remote operation. Some local clubs offer remote station access for members, and some other stations are available for individual use. Maybe you can team up with some friends and setup your own remote station.