A few weeks ago, I mentioned that Jonathan (KM4CFT) sent me one of his new QRP end-fed half-wave/random wire antenna kits.
When my friend, Alan (W2AEW), caught wind that I planned to buy some 26AWG wire for this build, he sent me a spool of wire from a large reel he’d recently picked up at a hamfest.
What a nice guy! The blue wire is absolutely ideal for portable antennas.
Being the nice guy he is, Alan actually published a video about building Jonathan’s antenna kit on his YouTube channel. I highly recommend watching it!
Before I received the kit, I already knew what type of antenna I’d build: a 30 meter end-fed half-wave (EFHW) linked with a 40 meter extension. This antenna design has been on my mind for some time and Jonathan’s kit was the perfect excuse to build one.
Why a 30M EFHW with a 40M extension? Because a 40M EFHW gives me excellent SWR matches on 40, 20, 15, and 10 meters without needing an ATU. A 30M EFHW gives me matches 30 and 17 meters.
Thus, with one linked wire antenna, I can cover 40, 30, 20, 17, 15, and 10 meters! That’s a lot of bands!
And since the antenna needs no extra matching, it’ll work with my transceivers that lack an internal ATU.
In fact, I originally thought about this antenna design to use with my Mountain Topper MTR-5B which covers 40, 30, 20, 17, and 15 meters.
I built this antenna by first trimming it for a 1:1 match on 30 meters including a loop and strain relief to attach the extension.
When I was satisfied with my 30M EFHW, I then made the 40M extension, attached it to the 30M section with 2mm bullet banana connectors, then trimmed the antenna for a 1:1 match on 40M.
I spent the better part of 60 minutes trimming this antenna. I feel like patience really pays off because it’ll set up the antenna for good matches on all of the upper harmonics. Admittedly, I was a bit pressed for time that day, so I only tested this antenna in one configuration (an inverted vee shape) so hadn’t checked the SWR as a sloper or vertical.
My advice is to aim for a 1.3:1 or better match on 30M and 40M–that should be very doable if you wound your transformer correctly.
This was my first attempt at making in-line links, so I wouldn’t consider link my method as a “best practice”–rather, check out K7ULM’s guidance for making in-line links.
I should also note that Jonathan also kindly sent me one of K6ARK’s 3D-printed antenna winders. It’s a brilliant and easy-to-deploy design. Check out Adam’s Printables Page for loads of designs you can print at home.
First POTA Outing!
On Friday, November 17, 2023, I had my first opportunity to play POTA with my new antenna.
I made my way to the Sycamore Flats Picnic Shelter in Pisgah National Forest (K-4510).
We were expecting rain, so I packed my Discovery TX-500. Turned out that we never got full-on rain (we needed it) but we had some very light drizzle and misting.
I wanted to deploy my antenna as a sloper (with the feed point near the ground) so I chose a site with tall trees spaced the right amount of distance from a picnic table. In this particular case, I actually set up in a picnic shelter that hadn’t been reserved.
Check out my activation video (below) for details.
- lab599 Discovery TX-500
- TELESIN Carrying Case (for the TX-500)
- ABR Industries 25’ RG-316 cable assembly with three in-line ferrites (Use Coupon Code ABR10QRPER for 10% Discount!)
- KM4CFT End-Fed Antenna Kit (eBay partner link)
- Key cable: Cable Matters 2-Pack Gold-Plated Retractable Aux Cable – 2.5 Feet
- BaMaKeY TP-III Ultra-Compact Twin Paddle
- Red Oxx Micro Manager
- Bioenno 15 Ah LiFePo Battery (Model BLF-1215A)–As I mention in the video, this battery is overkill for the TX-500. Typically I use a 3Ah battery.
- Weaver arborist throw line/weight and storage bag
- GraphGear 0.9mm 1000 Automatic Drafting Pencil
- Rite In The Rain Top Spiral Notebook
- Camera: original OSMO Action Camera (the OSMO 4 is the current version) with Sensyne Phone Tripod
On The Air
Since I 1.) had a microphone, and 2.) had a good internet connection to spot myself, I decided to do a little Single Side-Band during this activation! Sadly, I think this might have been the first time I operated voice during an activation in all of 2023–!!
If I’m being honest, it had been so long since I operated voice, I felt a bit rusty when calling CQ POTA.
My very first contact was David (KQ4EFU) who gave me a Park-to-Park! Thanks, OM.
I had a little pileup going on at times while operating SSB.
The really fun part was that two hunters made cross-mode contacts with me: they called me in CW and I answered them in SSB. That was a first for me! Talk about a brilliant way to break through an SSB pileup.
In total, I logged 23 contacts in in 19 minutes using SSB .
Next, I lowered the antenna, removed the 40M link, then raised it again–a process that maybe took 2 minutes.
I then started calling CQ POTA on the 17M band. I chose 17M since I thought it might be a little less active than 30M. I had a friend visiting town and planned to meet her for coffee and didn’t want to be late. I hate ending activations with a lot of hunters still calling.
I worked an additional seven contacts on 17 meters giving me a grand total (and round number) of 30 logged.
I should add, it was brilliant working Alan (W2AEW) on17M–he got to hear what his wire sounded like on the other end of the wireless!
Here’s what this five watt activation looked like when plotted out on a QSO Map (click to enlarge–note that the red lines are 40M SSB and the green lines are 17M CW):
Here’s my real-time, real-life video of the entire activation. As with all of my videos, I don’t edit out any parts of the on-air activation time. In addition, I have monetization turned off on YouTube, although that doesn’t stop them from inserting ads before and after my videos.
I’m so pleased with the 30/40M linked EFHW, I think I’m going to build three more: one from a KM4CFT kit, one from a Tufteln kit, and one from a K6ARK kit. That should cover all of my antenna kit-making friends!
This is such an easy antenna to build and removing the link during an activation to shift between 30/17 and 40/20/15/10 meters is really simple and quick.
I should add here if you’re only interested in 30M and above, you could make a 20M EFHW with a 30M linked extension. The resulting antenna would be a good 15′ shorter, but you would lose 40 meters which I find to be a valuable band for both POTA and SOTA.
You’re going to see this KM4CFT 30/40 antenna in several upcoming field reports and videos!
I hope you enjoyed the field report and my activation video as much as I enjoyed creating them.
Of course, I’d also like to send a special thanks to those of you who have been supporting the site and channel through Patreon and the Coffee Fund. While certainly not a requirement as my content will always be free, I really appreciate the support.
As I mentioned before, the Patreon platform connected to Vimeo make it possible for me to share videos that are not only 100% ad-free, but also downloadable for offline viewing. The Vimeo account also serves as a third backup for my video files.
Thanks for spending part of your day with me! Have a brilliant week ahead!
Cheers & 72,