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:

 

20150523_090739

 

 

 

 

 

 

 

 20150523_090656

 

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.

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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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