From: Kurt Schraner
Date: Fri, 15 Jun 2001 10:46:52 +0200
Subject: Re: [TSSP] Short Coil Experiments
Hi Paul, all,
the new measurements of the d=0.385m; h/d=1.15 coil are available now.
The main difference to the former measurements is the availability of a
better defined ground plane, in form of a galvanized wire mesh (3.4 x
2.8 m, approx.). For comparison I repeated measurements for 2 of my
formerly tested coils. I'm not able to attribute the fairly big
differences in f1, relative to the February tests, however I'm not very
trustful to my RF-generator equipment, - not regarding frequency, but
impedance. I've to investigate in this. The low-Z amplifier too seems
not to work properly. And even my outdoor-situation is rather
constrained space: The housewall is only about 1.5m away, and garden
plants disturb the free space on the other side ~1.5m away. The new
measurements however, should not be worse than my last ones. I'm yet
quite unhappy with the precision :-(.
Your support to prepare the tests, Paul, was, like ever, great!
Cheers
Kurt
Measurements of June 12/13th, 2001
Outdoor measurements with distance to groundplane ~ 0.5m
Date 12.06.01 12.06.01 13.06.01 13.06.01
Coil Sk-38cm Sk-38cm Sk-38cm Sk-38cm
turns 346
L @ 1 kHz 28.12 mH
Q @ 1 kHz 17.3
DC resist.R 9.2 Ohm dito dito dito
h 0.44 m
d 0.384 m
b 0.435 m
awg
wd(insulated) 1.2 mm ( 1.0 mm blank wire)
Probe: Ant. base curr. Ant. Ant. Paul's Error
RF Generator: Low Z Low Z Siemens Siemens predicted cal-exp%
Fres,exp f 1: 217.95 217.866 221.3 221.24 230.3 kHz 4.10%
Higher f 3: 505.57 503.173 506.5 506.17 556.9 kHz 10.02%
f 5: 748.76 747.42 881.6 kHz 17.95%
f 7: questionable values ----> 831 847 1221.1 kHz 44.17%
f 9: 1569.1 kHz
Bandwidth and Q
f 1: 218.04 221.3 221.24 kHz
71% f 1+: 219.04 222.43 222.33 kHz
71% f 1-: 216.95 220.22 220.07 kHz
Q : 104.3 100.1 97.9
------------------------------------------------------------
Outdoor measurements with distance to groundplane ~ 0.5m
Date old:10.02.01 new:13.06.01 10.02.01 12.06.01 13.06.01
Coil Sk-5cm Sk-5cm Sk-5cm Sk-5cm Sk-Long Sk-Long Sk-Long
turns 934 1976
L @ 1 kHz 5.203 mH 67.7 mH
Q @ 1 kHz 1.52
DC resist.R 21.7 Ohm dito dito dito 55.2 Ohm dito dito
h 0.411 m 1.402 m
d 0.0511 m 0.161 m
b 0.503 m 0.5 m
awg 26.108 22.053
wd(insul.) 0.425 mm 0.64 mm
Fres,cal f1:1068.4 Paul's 158 Paul's
Diff 16.80% cal-exp -2.10% cal-exp
Fres,cal f1:923.8 Wh./Medh. 139.3 Wh./Medh.
Diff 1.00% cal-exp -13.70% cal-exp
Probe: Ant. Ant. Ant. Ant. Ant. Ant. Ant.
RF Gen.: Siemens Siemens Heath Heath Siemens Low Z Siemens
Fres,f 1: 914.76 979.72 969.8 970.94 161.45 152.34 152.27 kHz
RF Gen.: Heath Heath Heath
f 3: 2428.7 2430.77 2430.44 386.43 387.157 387.1 kHz
f 5: 5300 5299.8 5283 562.04 564.216 564.42 kHz
f 7: 6924.6 6918.3 710.32 713 713.39 kHz
f 9: 8643.1 8580 ~847 850 850.9 kHz
f 11: 972.94 973.27 kHz
Bandwidth and Q
f 1: 152.268 kHz
71% f 1+: 152.716 kHz
71% f 1 -: 151.79 kHz
Q 164.436
------------------------------------------------------------
------------------------------------------------------------
Equipment:
Siemens --> Siemens Level Oscillator W2087 (200Hz...1620kHz)
(buildt-in f-counter with XXXX.XX kHz display)
HP 180A Dual Channel Oscilloscope (50MHz)
Escort ELC-131D LCR Meter (for L+Q @ 1kHz and 120Hz)
Metex M-3860M Digital Multimeter (for R with DC)
Heath --> Heathkit Laboratory RF Generator
Low-Z Amplifier 0...700kHz (Terry's; with Op.Amp.LM12CLK)
Ant. --> Antenna, 1.2 m distance from coil
Ground: (zinc-)galvanized iron-mesh(13mm mesh) 3.4 x 2.8 m
------------------------------------------------------------
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.