Hello Neno,

Influence of PVC wire insulation on wave propagation is just a few
percent. Most of the field lines go through air. I did a calculation
myself (however results are in Dutch language). When the wire is
thicker, the influence of same layer of insulation becomes less.

The soil has significant influence on resonant frequency and steepness
of resonance of the radials. When you use many of them the length
becomes less critical. You can also use elevated radials (for example
about 4 radials 1..2 m above ground).

However when VSWR is OK with short radiator or shorter radials and you
don't have common mode problems in the coaxial feed line, I would not
worry.

When you are still curious, you might model the nearby structures in
your NEC file and try to simulate the influence. A mast at 5m distance
is within the near field, so you may expect some coupling.

Instead of cutting, you can also roll them up (beginning at the end),
so you can re-extend them when required).

Best regards,

Wim
PA3DJS
www.tetech.nl


Thanks for help.
I cut radials to 3.25m and left vertical to 5.1m .
Now SWR is 1.3:1 on 14.020
I hope it will work good.
Eznec was very helpful too.
73 9A4MN Neno