Why I build EFHW antennas

When you're running QRP (low-power) radio, every watt matters. The End-Fed Half-Wave (EFHW) antenna has become a popular choice among hams for good reason. Whether you're operating portable, setting up for POTA (Parks on the Air), or working from your backyard, the EFHW antenna offers reliability, portability, and solid performance. I enjoy POTA the most and frequently make the short trip to K-3036 right down the road at Martin Creek State Park. Here’s why I take my own EFHW with me.

1. Efficient with Low Power

In QRP, you need your antenna to make the most of limited power. The EFHW is known for its efficiency, even with low-power rigs. It delivers a strong signal, ensuring you’re heard without needing a lot of power—perfect for making contacts with a small, portable setup.

2. Easy to Set Up and Carry

The EFHW is designed for easy deployment. Whether you’re in the park, on a mountain, or just out in the field, this antenna can be set up quickly. A tree branch, a pole, or even a telescoping rod can get you on the air fast. Its compact design makes it simple to pack and transport. I typically use a telescoping fishing rod and have even deployed it over the water from a fishing pier!

3. Works Across Multiple Bands

The EFHW's ability to cover multiple bands is another standout feature. With the right transformer—like my own End-Fed Half-Wave QRP Transformer Antenna on my Etsy store—you can switch between popular bands like 40, 20, and 10 meters. This versatility allows you to work different frequencies without needing constant adjustments.

4. Perfect for POTA and SOTA

For POTA or SOTA (unfortunately, no mountains anywhere close here!) operators, the EFHW antenna is an excellent choice. It's portable, quick to set up, and performs well without needing a lot of gear. You can spend more time enjoying the activation and less time fussing with equipment.

5. Beginner-Friendly and Reliable for All

You don’t need to be an expert to get started with an EFHW antenna. It’s easy to use, which makes it great for beginners. At the same time, experienced operators appreciate its reliability and performance during portable operations.

DIY battery pack for POTA

I've been playing around with some different sized cells to build some physically smaller battery packs for my QCX-minis. I only use them about an hour or two at a time, so I don't need a massive power source. However, most store-bought (relatively cheap) LiFeP04 batteries start around 6Ah. So I began looking for small cells to build a custom pack or two.

I found some neat little LiFeP04 cells the same size at AA alkaline cells. Since the are 3.2V each but still fit anything that takes a AA, I had to have a talk with the family to make sure no one accidentally used the "purple" batteries! I also bought a universal charger that could charge them. The unit also charges NiMH, Li-Ion and NiCad batteries with the flip of a switch.

I bought a few balancing units and then complexly over engineered a battery pack. It worked, but it not practical. So, I ordered a case with a lid, power switch and power cord and simplified my life. Now I

POTA outing with the DigiBox

With the extended Christmas break, I had an opportunity to head out to Martin Creek Lake State Park (K-3036) for a POTA activation. I used my revamped DigiBox and my homebrew EFHW antenna. The weather was perfect with clear sunny skies and about 63 degrees outside. It was very comfy in the sunshine! 

I found a covered picnic table near the lake and setup my equipment. I extended my 21-foot collapsible fishing pole and used a rod holder stuck in the ground about 40 feet out from the picnic table to hold it, basically creating a sloper antenna.  

Over all, it worked very well! I made just over 36 FT8 contacts in about an hour and a half. I found the bottleneck on on working contacts was my own clumsiness in clicking stations! Typically, my signal reports were about 10db to 15db below the reporting stations, which I felt pretty good about considering I was running about 4w and the bands were FULL of station. 

Upgraded digital GoBox

After several months of use, I decided to upgrade my digital GoBox. The new version includes a larger screen (10" vs 7"), solar charging capabilities and a nicer layout. I used some white marine board to create a mounting point for all the equipment. This gives it a much cleaner look. I also installed a 30A solar charge controller to allow for solar panel use if desired.

I wound up frying to Raspberry Pi 4 computers with the old setup. The best guess on why is that the USB port was getting confused with the RPi and supplying it with 12V instead the required 5V. I removed the blown diode (was not able to salvage the pads for a replacement) and use the RPi anyway.

I also added a Real Time Clock (RTC) module to help keep the unit calibrated. I previously had installed a GPS unit to update the time, but the RTC module is easier, smaller and cheaper. It uses the DS3231SN chip to maintain accurate date and time  

I wrapped the module in some shrink wrap and connected it via the i2C bus. It seems to work very well and includes a rechargeable Lithium Ion battery. I followed these instructions to setup the software portion. 

Yellow is for Solar!

I'm a big proponent of using Anderson PowerPole connectors on all radio gear. They have become the standard for ARES and other emergency radio services, so it just makes sense. However, I wanted to make sure I didn't mix up wires from different voltages, such as power lines coming in from by solar panels. 

I ordered a handful of yellow housings and have begun swapping over all the connectors that would bring solar (often 18v - 24v). Hopefully, it will be an extra-level of protection when hooking things up in a hurry!

Wires-X on the N5RCA repeater

I've had an HRI-200 for a few years now, but for most of that time, its sat silent in my GoBox. I mounted it there along with a FTM-400DX to use when I deployed the box. Typically, the box sits on my desk in my home QTH and I use it and the FT-991 (also in the box) as secondary base rigs.

Since the club swapped out our repeater controller for a (newer) DR-1 Fusion machine, I decided I would try to setup the HRI-200 as a remote Gateway. We don't have internet access (or even easy physical access) to the repeater site, so having a remote Gateway is the only way we can do it. 

The whole process was rather easy. I installed the Wires-X software on my PC and connected the radio and HRI-200. Now, anyone with a Wires-X capable rig, can connect to the Wires-X network, choose a room and talk with other distant stations. Try it if you get the chance!

General Instructions (refer to your radio manual for exact instructions):

• You must use a Fusion capable radio (FT-991(a), FTM-100DR/200D/300D/400D/500D, FT-1/2/3/5-D). You may need to adjust the "Wires-X" settings in your configuration menu. Again,

Low-power antenna build

I decided to try and miniaturize my EFHW antenna. I typically use this kind of antenna with one of my QCX-minis or my QDX (both from QRP Labs) so it would never see more than about 8 watts maximum. So far, I've always built them with FT140-43 cores which work very well, but are somewhat bulky. A friend said they didn't really look like "QRP" antennas to him, so I thought I'd try something smaller.

To build this mini-version I used use two stacked FT50-43 cores, so yes, they are small. I wound them like some of my others to be 64:1 transformers using 3 turns on the primary and 24 on the secondary. I included a 100pf capacitor as well. Then sealed the whole thing inside some shrink tubing.

I cut a wire for 20m and tested it out and it tuned very well. Next, I'll take it to the field and try it out in