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F5DQK March 2007 1
Moonracker YG5-4 transformations
1/ Original Moonracker YG5-42/ YU7EF transformations3/ SWR meas
F5DQK March 2007 2
Original Moonracker YG5-4
Measures at 70.2 MHz using Mmana simulator
SWR F/B ratio
DimensionsWhole aspect
F5DQK March 2007 3
Original Moonracker YG5-4
Original Moonracker design- Equal spacement between elements- Gamma Mach feed (serious problems with humidity and torque)- F/B ratio not optimised
Impossible !!! What’s dBb ??
Lboom =2.66m
Gain =7.83 dBdF/B=14 dB
F5DQK March 2007 4
Original Moonracker YG5-4
Gamma mach feeding
Gamma capacitor
F5DQK March 2007 5
Zoom on gamma mach feeding : too much distance !!
Original Moonracker YG5-4
Difference between diameters 19,85 – 19,07 = 0.78 mm, that’s far too much !!
F5DQK March 2007 6
Zoom on rear of feeding box
Plastic cap
Original Moonracker YG5-4
Silicon compound
F5DQK March 2007 7
Original Moonracker YG5-4
Zoom on front of the feeding box : All the water can enter here !!
Box front (UHF feeding)
Metal screw WITHOUT dedicated nut part (very ugly) !!
Shield contact NOT reliable in the time !
F5DQK March 2007 8
Initial elements fixing on boom and adjusting
Original Moonracker YG5-4
F5DQK March 2007 9
F5DQK March 2007 10
Moonracker YG5-4 transforming from YU7EF
SWR F/B ratio
DimensionsWhole aspect
Measures at 70.2 MHz using Mmana simulator
F5DQK March 2007 11
Moonracker YG5-4 transforming from YU7EF
Finished antenna
- No more equal spacement between elements- Direct 50 Ohm feed
F5DQK March 2007 12
Moonracker YG5-4 transforming from YU7EF
Construction of a brand new isolated dipole
- Dipole substitution- New elements spacements
Gain =7.86 dBdF/B = 18 dB
F5DQK March 2007 13
Moonracker YG5-4 transforming from YU7EF
Dipole feeding details
N connector
Dipole fixing parts
Plastic box 70x70 h=40
No rain can enter
Diam 12/10 mm
Lucoflex plate 300x100 h=4 mm
F5DQK March 2007 14
Moonracker YG5-4 transforming from YU7EF
50 Ohm dipole ends
Diam 12 Diam 10
Split on length 30 mm No rain coming from both ends
F5DQK March 2007 15
Moonracker YG5-4 : last improvements against rain
Aluminium Scotch on all previous holes (here dipole and gamma feeding)
F5DQK March 2007 16
F5DQK March 2007 17
Moonracker YG5-4 measures
SWR with MFJ-269 analyser 1.5 1.2 1 1.2 1.5
Direct, mast at 3 meter heigth 69.5 70.18 70.5 70.8 70.95
+1 cm on all elements 69.25 69.83 70.28 70.5 70.68
Yagi now at 11 meter heigth 69.1 69.96 70.3 70.56 70.77
+2 cm on all elements - coming