Im still struggling with a 110 foot dying spruce tree and wonder if Ill
every get the wire up it before it snaps in these high winds. Spruce trees
are dying/have died in large numbers in S central alaska. Beetle carrying
virus.
In looking at my LF Inverted L, and specifically the 3 wire top loading
wires - I've a couple of questions...
1. I see a recommendation that the vertical part of the Inv L aerial
wire(s) should be a single wire (ZL recommendation), or if not then three
or how many wires should converge to a single point at the bottom. Why is a
single wire recommended over a multiple? Em thinking losses into nearby
objects? Wouldn't a multiple vertical wire feed increase "good non lossy"
C and increase Ra?
2. Ive seen a large amount of schematics both for commercial and ham top
loading.of T and L's ...Say for a three wire top loading spaced 1m apart -
should the wires at the far/near end all be shorted together or left open?
Does this affect the total cap either way, or is it just for electrical
"circuit" stability?? Does it make any difference if they are shorted at
any point along the top?? Is there a recommendation which proves open
versus short is better ?
Mine are open all the way and Im using a converging 3 wire vertical wire
feed... I see shorted at the ends, shorted half way, open ended solutions
from my peers here...
Im trying to rationalize that the end of the loading wires are at Zero
Current (no different circulating/local currents between the wires?).. and
it may not be an impedance thing but may help reduce high voltages as the
surface area at the end is now a lot larger...and may reduce corona.
Most commercial T's for NDB short out at the far ends..and I do see single
and multiple wire converging vertical wires, so I guess they are all right
But a lot of the drawings ref materials show them open! Arghh.
Any experiences welcomed...
Laurence KL1X -
|
