X1M EFHW Antenna

I built an EFHW (End Fed Half Wave) wire antenna and a slingshot launching system to put one end up in the air in  a tree limb when I go out on one of my motorhome camping trips. I’ll post something on that when I get around to taking some pictures.

I also built a small tuner box for the EFHW that works from 40M thru 10M. This little unit (approx 2″ x 3″ x .7″) uses a polyvaricon and a toroid to step the X1M’s 50 ohm output to about 3000 ohms. The unit has a built in SWR bridge with an LED as the indicator. a switch allows the LED to indicate forward power or reflected power. Here are some pictures:












Here’s the schematic:

EFHW Tuner

Note: The L3/L4 core is really an FT37-6.

There’s a DPDT switch that switches the bridge/measuring circuit out when not in the ‘Tune” mode.

Contact me about more detailed information if you decide to build this.


One Response to “X1M EFHW Antenna”

  1. Jack Purdum, W8TEE December 24, 2015 at 11:40 am #

    This is pretty cool! Any idea of what the max power might be (e.g., < 10W)?

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