QRP L Matcher for 2 End Fed Long wires: LD = 158m KD = 42m
ON7DY - 20150318
Target was to match both wires for use in combination with the Ultimate3 QRP WSPR beacon
for 7 10 an 14Mc
On hand of the SWR analyzer Fox Delta (I2TKZ K7SNF VU2FD) both long wires react as:
Long wire 42m – 6m agl:
Long wire 158m – 6m agl:
The fact that end fed wires react with very high impedances, the use of a L tuner seems a
solution. The values of the L and C components where determined on hand of a TRX (TS590S)
and an automatic tuner MFJ993B, witch results in:
L tuner - bepalen H en C waarden
Freq
14000
14100
14200
Antenne 158m
µH
C in pF
0,17
0,080
0
105
105
90
Antenne 48m
µH
C in pF
0,35
0,350
0,25
75
75
75
WSPR freq range
10100
10140
10150
0,52
0,720
0,6
265
193
193
0,97
1,150
0,97
250
235
235
7000
7040
7100
7200
1,83
1,480
1,48
1,32
412
458
412
412
0,43
0,250
0,25
0,17
958
912
735
633
WSPR freq range
WSPR freq range
If used toroid’s, I chose the T37-2 because more turns on the core makes it less critical.
micro H
Korte ant
Lange ant
14Mc
0,35
0,08
FT37-61
#tr
2
1
T37-2
#tr
9
4
10Mc
1,15
0,72
FT37-61
#tr
5
4
T37-2
#tr
17
13
7Mc
0,25
1,48
FT37-61
#tr
2
5
T37-2
#tr
8
19
The practical realisation is base don a variable capacitor 25-245pF in combination with 2 switchable
capacitors 100pf and 680pf.
The selection of coils is made by a rotary switch 5 positions
The basic drawings are as below:
Using the SWR analyser it is possible, although not so easy, to find the resonance points for both
antennas for the WSPR freq 7 10 and 14Mc
Long wire End Fed 42m – 14.101 – SWR 1.03
Long wire End Fed 42m – 7.059 – SWR 1.02
Long wire End Fed 42m – 10.121 – SWR 1.03
Long wire End Fed 158m – 14.181 – SWR 1.35
Long wire end Fed 158m – 7.042 – SWR 1.18
Long wire end Fed 158m – 10.135 – SWR 1.21
How the prototype look like
See some SWR results to compare both antennas in combination with the Ultimate3 QRP beacon –
350mW – KD 42m - LD 158m
20150315 12u 20m LD
20150228 12u 20m KD
20150307 12u 30m KD
20150314 12u 30m LD
20150225 12uur 40m KD
20150314 12u 40m LD