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Showing posts from August 25, 2019

5/8 10m vertical and K3 with TR-2018 HD 144MHz

28MHz  5/8 wave base  6m a.g.  vertical aluminium tube 20mm 2m50 and a fishing rod with shunted 1.5mm2 wire total length 6,4meter = 0.64 x wave   Base of former CB 1/2wave or  5/8wave used with external coil 3 wgd  ( 1 wdg in the socket) The original coil is removed ( 5+3 wdg 32mm close wound) 3wdg gave best matching using 2 radial wires 1:1.6   got 1:1.2 when 1 radial hanging vertical down... results are very good in compare with the higher h-dipole although the groundwave of DB0PBS at 50km only is received on the dipole. Other signals over iono Es gave comparable snr sometimes even better      The impedance of a 5/8 wave vertical is given as (75 -425j) Ω    needed is XL  +425j to balance out the capacitive -425 Rothammel  say  2.3uH for D/d=4000  the ratio of lenght and conductor diameter does have influence on the inductance the thinner the conductor the higher the inductance The original coil in the base for 11m is  8 wdg 32mm = 2.8uH The CD 11m vertical

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