FRIDAY AFTERNOON BUILDING SESSION
Friday afternoon, 3-5 p.m.
Build A Self-Contained End Fed Random Wire Antenna (QRP Version, up to 10W CW / 20W PEP SSB)
Cost of kit/instructions: $40
Hams who enjoy POTA, SOTA and other portable operation have discovered that the End Fed Random Wire antenna is an effective option when operating in the field — and on Friday afternoon participants in this Building Session will construct a complete 40-10 meter “EFRW” system of their own!
End Fed Random Wires are really not random at all but are actually cut to carefully chosen lengths that are NOT resonant on any band of interest. Typically, their feed impedance is several hundred ohms. EFRW designs such as this one usually assume a 450 ohm feed impedance for design purposes and use a 9:1 impedance transformer to step that impedance to something between, say, 25 ohms and 100 ohms. Feed impedances in that range are easy for almost any antenna tuner to handle, and the result is an extremely frequency-agile multi-band antenna.
Please note that you will need to use a tuner with this antenna, but virtually every built-in tuner or outboard tuner will handle that matching task easily.
This unique project is a self-contained and easily portable system built around (and IN!) a handheld antenna winder! Built using an FT82-43 core, the matching system is conservatively rated for 10 watts CW or 20 watts PEP SSB. Of course, you’ll need to derate it if using digital modes.
The unit you’ll build features a BNC connector for connecting to your radio, plus a captive-wingnut connection post for attaching the antenna wire. In the interest of simplicity in the field and ease of construction, the counterpoise connection on this antenna system is made via a crocodile clip.
The kit includes all parts and hardware needed to build the matching unit and winder system, plus the antenna wire (about 29 ft in this case) and counterpoise wire (about 17 ft). Also included are detailed and fully illustrated instructions.
Sign-Up Here: On This Google Form
Note: Each Antenna Project has its own sign-up page. We have set a limit of 12 for each antenna build but are allowing 16 to sign up just in case of no-shows.
Return to: The Antenna Build Project Page