Month: January 2014

Wire current rating for single FEP (Teflon) or Silicone insulated (200°) conductor in free air (30°).

AWGCond dia (mm)CSA (mm^2)R/km (Ω)Imax
26.533.60.513241
35.826.70.647209
45.221.20.815180
54.616.81.03156
64.113.31.30135
73.710.51.63117
83.38.372.06101
92.96.632.6087.4
102.65.263.2875.6
112.34.174.1365.4
122.13.315.2156.6
131.82.626.5748.9
141.62.088.2942.3
151.51.6510.536.6
161.31.3113.231.7
171.21.0416.627.4
181.00.82321.023.7
190.910.65326.420.5
200.810.51833.317.7
210.720.41042.015.3
220.640.32653.013.3
230.570.25866.811.5
240.510.20584.29.93
250.460.1621068.59
260.410.1291347.43
270.360.1021696.43
280.320.0812135.56
290.290.0642694.81
300.260.0513394.16

Derived in part from data published by Wiremax.

 

Last update: 1st February, 2016, 7:27 PM

Speaker cable as RF transmission line

Speaker cable and similar Figure-8 twin in various sizes is popular as RF transmission line, particularly with QRP operators, especially those operating portable in the field (eg SOTA activators). Indeed, SOTA seems to have triggered a revival in the use of these cables. With the large number of online recommendations, one could be forgiven for thinking that a dipole and feed line formed entirely from #24 speaker wire is the antenna of choice.

With that in mind, this article looks at the performance of Jaycar WB1702 speaker cable, 14×0.14mm conductors (#24) with PVC insulation, cost $0.50/m.

Continue reading Speaker cable as RF transmission line

Last update: 16th February, 2014, 7:59 PM

Measuring matched line loss

Matched Line Loss (MLL) is the loss or attenuation of a transmission line terminated in its actual characteristic impedance, and usually give for some length, eg dB/100′, dB/100m, dB/m.

One method that occurs in ham radio articles is to measure the input resistance of a resonant s/c or o/c stub, and to calculate MLL as 8.686*Rin/Zo/length dB/unitlength. (This is not the only method, or even a good one, but it is commonly used.)

Continue reading Measuring matched line loss

Last update: 20th April, 2020, 6:56 PM

Wire dipole on 160m

Discussion with a correspondent recently ranged onto the effect of some conductor materials in antennas. This posting reports the feed point impedance and internal efficiency (meaning power not turned into heat in the structure divided by power input at the feed point) of a 160m half wave dipole (80m long, centre fed, 20m above average ground and using 2.6mm diameter single core wire).

Continue reading Wire dipole on 160m

Last update: 8th November, 2015, 3:55 PM