Category Archives: Antennas

End Fed HalfWave 40-10m

After being asked to activate a particular park on the air, I was told that an end fed half wave antenna would work well for portable operations. So with that information I began researching how to build an EFHW for 40-10m. I’ve build single band dipoles for these frequencies, but I wasn’t sure about how to go about this.

The main part of this antenna is a 49:1 balun. It is a transformer that has a 7:1 turns ratio, and isn’t too tough to make. So follow me as I lead you on a photo journey of how I built my 40-10m EFHW.

I cut about 136 feet of wire for the antenna. This can be shortened later when it comes time to trim and tune the final product.

Antenna wire wrapped around a spool for easy transport.

Winding the toroid was the next challenge. It wasn’t as difficult as I thought it would be. I followed Steve Ellington from Youtube. Two wraps with twisted wire and then 14 wraps with the long length wire. I used a drill and a vice to wind the two lengths of wire together. Watch Steve wind his transformer. He explains it much better than I can. Solder it into the junction box as shown in the image with a 100pF 15kV cap from tip to ground on the SO-239.

K1TA created this image to show how to wind the toroid. I used 1 core for barefoot ops.
The transformer soldered into the box.

Testing this with my RigExpert AA-170 was a joyous occasion. I was quickly able to loop the end of the wire about 12 inches and zip tie the end together so I could string it up with paracord. 40m, 20m, and 15m were 1.7:1 SWR. 10m was 2.2:1 in the CW portion and 2:1 or below for the voice portion. I consider that a win!

1 4” X 4” X 2” PVC Junction Box (LOWE’S)
1 500 Ft. roll 14 AWG Solid (LOWE’S)
A few feet of 15 AWG Magnet wire Remington p/n 15SNSP.125 (DIGI-KEY 2328-15SNSP.125-ND)
1 Ferrite Toroids / Ferrite Rings 43 Toroid 12.7mm 61mm
p/n 5943003801 (Digi-Key 1934-1592-ND)
1 100pF +/-10% Capacitor 15kVDC p/n HVCC153Y6P101MEAX (DIGI-KEY BC5419-ND)
1 SO239 chassis mount female connector (Amazon sells these)
Various stainless steel nuts, bolts & eye hook

Inverted Vee 40m Dipole and Mast

My Purpose

Antennas in the back yardIt has been a long time since I have experimented with antennas and yard ornaments (tall, antenna holding things like towers and masts), but recently I have been annoyed by the performance of my Hustler 5BTV vertical. I have vertically polarized noise that tends to aggravate me, so I wanted to try an inverted vee dipole to see if conditions improve.

Lately, I have been working CW, and I have had some fading signals and noise, so I figured that the dipole might help some with this. The issue is that I needed somewhere to mount this thing! Continue reading Inverted Vee 40m Dipole and Mast

10 Meter Mobile

HTX-100 on the Jeep's dashI realized on October 12, 2013 that it had been eleven months since I had last made an HF contact of my own. I made some during Field Day 2013, but those weren’t really mine. There were several reasons why I couldn’t get on the air. I had lots of receive noise, little time, and an uncomfortable ham shack. I believe that I have solved these problems. Continue reading 10 Meter Mobile