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2015-03-29

EFHWA TRANSFORMER

Some tests with transformer for end fed half wave antenna, EFHWA.
2 turns primary + 150 pF, 16 turns secondary seems to be good for 40-10m
3 turns primary + 150 pF, 24 turns secondary is good for 80-20m




FT240-43
Primary : 2 t, 
Secondary : 16 t

LIGHT TWIST

C=150 pF              Rtest = 3,1 kΩ

     


3510 kHz
7029 kHz
10140 kHz
14016 kHz
18096 kHz
21054 kHz
24930 kHz
28041 kHz
SWR = 2,61
SWR = 1,33
SWR = 1,11
SWR = 1,28
SWR = 1,41
SWR = 1,39
SWR = 1,30
SWR = 1,44



FT240-43
Primary : 3 t, 
Secondary : 34 t
TIGHT TWIST

C=150 pF              Rtest = 3,1 kΩ


3510 kHz
7029 kHz
10140 kHz
14016 kHz
18096 kHz
21054 kHz
24930 kHz
28041 kHz
SWR =  1,57
SWR = 1,29
SWR = 1,33
SWR = 1,65
SWR = 2,46
SWR = 3,85
SWR = 7,14
SWR = 13,63
 


Construction of 40-10m transformer
The plastic box is G311 (IP65)
Ref Farnell 1094700 price< 8 €


Ready for real test with End Fed

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