From: Kurt Schraner
Date: Sun, 10 Jun 2001 08:15:45 +0200
Subject: Re: [TSSP] Interesting article on Medhurst, Wheeler, modeling,etc.
Hi Paul,
an old "air core" choke-coil I'm owning (was used in a former high-power
TC at an insulator's company (=3DLangenthal)) , will be the subject of
some of my measurements, if you think it's appropriate:
Geometric data:
Wire diameter, bare Cu 1.0 mm
Wire diameter, insulated 1.2 mm (cotton spun)
Diameter of former d =3D 0.383 m
Length of former 0.501 m
Former's wall thickness 8.0 mm (Material: hard paper, ~ pertinax)
Winding length h =3D ~ 0.44 m (cotton insulation is compressible!)
Number of turns N =3D 346 (counted manually)
Aspect ratio h/d =3D 0.44/0.384 =3D 1.15
Spacing ratio sr =3D 346*1/440 =3D ~ 0.786
Height above ground b =3D ? m (not yet available)
Electric data (Multimeter & LCR-Meter):
DC Resistance R =3D 9.2 Ohm
Inductance L =3D 28.12 mH @ 1 kHz Q=3D17.3
Inductance L =3D 28.23 mH @ 120 Hz Q=3D2.29
I'm aware, the wall thickness of the former is really fat.
My small problems are:
- enough free space (...why this offer, for free access to an empty
industrial-hall is never arriving ;-)) ?
- My low-Z Amp (=3DTerry's design) is in a steel-metal-box of about
24x16x(h=3D)12cm: how should I "hide it" from the base feed of the coil
(Dig a hole into the ground? Move it away by 2m ?).=20
- How, exactly, is the most appropriate way, to feed the coil's bottom:=20
a) b)
o o o o
o o o o
o o o o
o o o o
o---. o o o
=A6 =A6
=A6 0.4mm Wire =A6 0.4mm Wire
=A6 =A6
.--------------- .------------------
Coax? Low Z Gen. Thin Wire? Low Z Gen.
.--------------- .------------------
=A6 =A6
-------------------------- -------------------- Ground
Ground will be a wire mesh (like chicken wire),
with ~ quadratic meshs of sidelength 13mm.
While b) is easier for me, I think your recommendation was more like a)
? I'm waiting the next non-rainy day, to perform the measurements
outdoors.
Cheers
Kurt
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.