Coils belong up high not at the bottom, too much loss where the max current is....

The helically wound vertical is a monobander, one reason i ditched it for the inverted L and autotuner at the bottom feed at the antenna.
It worked quite well, gave me the first qso's to Canada and the USA but the inverted L is higher, less lossy and about 6 - 8 dB better.
Get as much radials in at the feedpoint, anything in or on the ground will be detuned anyway, just cover as much ground as you can near the feedpoint where you have the most losses, my radials are from 30 feet long to one 300 feet long runnng in an U around the block of houses i live in.
Some are 4 inches above ground intertwined in the garden wood separation some run under the laminate in the house, under the house, through the front yard, etc.

At the feedpoint a 10 feet copper tube is in the ground and a 200 KOhm resistor connected to the Inverted L for static bleed off.
Several other 10 -20 feet copper tubes in the silty clay form the rest of the grounding one connected to the station with a large wire of 6 feet.
The house ground circuit is also connected to the grounding system, so that the kitchen sink is part of it as all copper piping etc.

I regularly put 1000 watt into the helically wound vertical, no corona, at the top i had a T hat with 2 wires of 30 feet long.

The Inverted L is 23 meter high, and the wire from the top to a tree is also 23 meter long, non resonant on 160 but that was done on purpose to prevent it from being a 1/2 wave on 80 with high impedance.
The MFJ 998 autotuner has no problem tuning it from 160 -10 with 1000 watts in, though the radiation pattern above 20 meter leaves a lot to desire.
There i use the OCF ( Fritzel FD-4) or the Imax 2000 from 17 to 10.

For 160 and 80 the inverted L is for DX a lot better as the OCF antenna.
40 and 20 depend on the conditions, i can swicth over easily with the heathkit antenna switch to see what antenna works the best at that time.
The helically wound T wll have a vertcal radiation, an inverted L also has a horizontal component.
Depending on the band and where the current is the highest you will get a mixed component sometimes mostly vertical and low angle of radiation, good for DX.\
The Helical had a pronounced dead zone after the groundwave and after 300 miles the first jump hit the ground again, the inverted L has a less pronounced dead zone.
THe inverted L has a groundwav extending daytime from 90 to 200 mies for good stations with a decent antenna, nighttime propagation for me is Europe up to 6000 miles easy and the USA and Canada, wintertime is the best for us, less atmospheric noise on the northern hemisphere.
Though i did work some nice DX in summertime as well.