I have an EF-40/20 that I intend to install in the attic of my house. Can I perform the initial tuning laid out on the ground, rather than stung in the attic. If not on the ground, perhaps raised 6 feet. This will eliminate the number of trips in/out of the attic which isn’t simple to do. Can I expect a big shift in tuning. I am only using a SWSR meter since I don’t have an analyzer.
No. if you were leaving it outside then tuning at 6 feet may be ok. But since you are putting it in the attic there will be far more interference and it will need to be tuned in the attic