Total posts : 45366
Don’t tune with modulation …
Unless by stroke of luck, the taps won’t bring you to final resonance.
Once you have it as high as you can go with taps, you need to do a final length adjustment. In the antenna type you’ve built, it should have approx 3″ cross slots in the short section attached to the top of the loading coil. It should be 1″ dia. copper pipe section, and of course a 3/4″ pipe for the main section.
With the top section slid inside the short section, I used a pair of hose clamps to tighten it, but only enough to hold it in position.
Then you have to work it up and down while watching the meter (or O-scope), stepping at least 3-4 ft. away from the antenna before each check. If it gets less than the reading with just the tap, work it the other way and it should rise to a point where the reading starts to get less again … and visa versa if it is more than the tap reading. Continue the process until you get the reading as high as you can. When you have it, your system is in resonance. Lock it in position by tightening the hose clamps.
It took me quite awhile to get mine adjusted. Patience is required. HTH …
P.S. – If you want you can stick a low range air cap, say 0-10 pF, to make small day-to-day adjustments to compensate for changes in atmospherics and ground conductivity. I don’t (I have great ground), but I’m pretty sure there are others who do.