What I remember is that the 14AVQ had a shunt coil across
the base to help raise the feedpoint impedance. It had more
effect on the lower bands where the antenna was electrically
shorter.
Other than providing a DC path for static discharge, it doesn't
do much on the higher bands. It isn't really necessary,
especially with a poor ground system where the ground loss
improves the SWR. But if the SWR is higher than you would
like on 40m, you can add a shunt coil to get a better match,
and it probably won't have a lot of effect on the other bands.