Link End Fed Half Wave Antenna and Tuner for SOTA
QRP Multi-band HF EFHW antenna for SOTA
Post updated 29 September 2017. I have inserted two additional links for coverage on 17m and 30m. I have changed the counterpoise wire from 1.5 metres to 6.8 metres long.
My take on a QRP HF EFHW inverted V antenna designed for use on five amateur radio bands 15m, 17m, 20m, 30m and 40m.
My preferred SSB operating frequencies are:
- 21.300 MHz
- 18.140 MHz
- 14.310 MHz
- 10.130 MHz
- 7.090 MHz
From the feed point the total length is 20.1 metres (65.94 feet).
Links are inserted at 6.69 metres (21 MHz), 7.85 metres (18 MHz), 10.05 metres (14 MHz) and 14.06 metres (10 MHz). For operation on 7 MHz close all links. The counterpoise wire is 6.8 metres long. The coax feedline between the EFHW tuner and the radio is 2 metres long.
VK1AD SOTA HF EFHW Antenna
Antenna winder: TET-Emtron (Perth), Squid Pole: Haverford (Sydney)
EFHW antenna 15/17/20/30/40m and winder.
nylon dog-bone end insulator
perspex squid pole center support
EFHW antenna components
Link Insulator: 30mm length of 6mm fibreglass rod, salvaged from a surplus UHF mobile antenna
Connectors: automotive spade connector male and female pair
Clamps: small black cable ties UV resistant
spade link closed
spade link open
close up – automotive spade link
Circuit – Impedance Matching unit rated at 15 watts
QRP EFHW Impedance Matching Circuit
EFHW match circuit
Inside the box
close up – T80-2 Toroid Permeability = 10, 25 turns tapped at 3 and 4 turns. 266 pf poly variable capacitor from EMTECH
Coax feed line between the impedance matching unit and the radio is a 2 metre length of RG58AU.
The EFHW antenna is a popular choice among VK SOTA activators.
First Published: 14 August 2014 Last Update: 29 September 2017.
Other EFHW antenna designs by VK SOTA activators:
Reference site: Steve Yates AA5TB The End Fed Half Wave Antenna
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