The guns are silent.

"All quiet on the Western Front."

Isn't it amazing that a lil' drop of 'rithmetic has a greater smoothing
effect than "pouring OIL on troubled waters" ?

==========================

Reg wrote -

A thick layer of insulation over an antenna wire is just
uniformly-distributed capacitance loading. As with ALL transmission lines,
an increase in capacitance per unit length results in a reduction in the
propagation velocity and a consequent reduction in the resonant length.


Capacitance increase depends on wire diameter, diameter over insulation, and
permittivity of the insulating material. The velocity factor VF due to
insulation thickness in the case of a long, straight, antenna wire, can be
estimated as follows.


d = wire diameter.
D = diameter over insulation.
h = height above ground.
K = permittivity of insulation.

K can vary from 2.5 to 6 depending on material.


Calculate A = K*Ln( 4*h/d )
Calculate B = K*Ln( 4*h/D )
Calculate C = Ln( D/d )

Then VF = Sqrt( A / ( B + C ))

Decrease in antenna length due to insulation = ( 1 - VF )*100 percent.


And unless the insulation thickness looks like 1" diameter coax with the
braid stripped off, for ordinary HF wire antennas at ordinary heights the
pruning will be lost in all the other things which might need a teeny bit of
pruning. As Roger advises "cut long and trim to fit". In practice, if a
tuner is in circuit, after taking the obligatory end-effect into account,
then I would guess pruning is seldom needed on simple wire antennas at
ordinary heights.
----
Reg, G4FGQ