Many thanks to by Mark (W2ITG) who shares the following field report:
Elecraft KX3/AX1 Field Report
by Mark (W2ITG)
I’m an avid POTA activator and wanted to try an experiment to see if I could complete an activation using just the Elecraft KX3 & AX1 on 40 & 20m SSB. I’ve seen others do it on CW but not on SSB. My CW learning is not going well by the way.
This was at K-1635 Washington Rock State Park 02-07-2024, with a beautiful view of the NYC skyline approximately 20 miles away.
My 1st attempt was a failure because I ran into SWR issues on 20m when I picked up the microphone & RF was getting into the audio as well. This was with the antenna mounted directly on the side of the radio using a 90 degree elbow connector, the AX1B bipod & an elevated radial connected to one of the case screws of the radio, unfortunately it didn’t work.
It’s a good thing I had brought along my Tuftln EFHW and telescopic carbon fiber fishing pole as well because it saved the day which allowed me to complete the activation. When activating make sure to have a backup plan, so far I have no incomplete activations.
Fast forward to 02-27-2024 I’m making another attempt but using a clamp mount, clamped on to the side of the picnic table, 25’ of ABR Industries RG-316 with built in CMC choke, the Elecraft AXT1 tripod adapter, and an elevated counterpoise.
I was much more successful, but barely. I did get my 10 contacts, 7 on 40m and 3 on 20m. This really took me by surprise as the AX1 is more of a compromise on 40 than it is on 20m.
Radio set up at a different picnic table.This clamp mount was taken from one of my BuddiStick setups.Notice the electric fence post in the background to elevate the counterpoise.The QSO map, it took me an hour and a half to get these 10 contacts.
Using the AX1 was quite the challenge to say the least. It does prove that even with a very limited antenna you can make contacts. My guess as to why it didn’t work as well on 20m, is poor band conditions. Living in the very populated northeast is what I believe allowed me to make more contacts on 40m.
Would I recommend buying this antenna? Most definitely, just as long as you know what it’s limitations are. I will try another attempt, but by trying 2 elevated counterpoise wires instead of 1. This antenna can use all the help it can get.
In the spirit of full transparency: he sent this at no cost to me, and, as a reminder, Chelegance is also an affiliate of QRPer.com.
I’ve been eager to take the 80-meter coil on a POTA activation because 1.) if it proved effective, it would be great to have such a low-impact, low-profile antenna for 80 meters, but 2.) it’s been very difficult to fit in an evening POTA activation with my family life.
It would have been difficult to gauge how effective an 80M antenna performs in the late morning or early afternoon when I typically activate local parks/summits.
On Wednesday, February 6, 2024, a two-hour window of opportunity opened. One of my daughters had a dress rehearsal that night, and I knew of a nice, quiet, secluded POTA spot only 25 minutes away.
Pisgah National Forest (K-4510) and Game Land (K-6937)
My original plan was to arrive at the Looking Glass Falls’ picnic area, deploy the antenna, fire up the stove, make some coffee, eat on-site, then begin my activation after the start of the UTC day.
So why wait for the new UTC day?
Mainly because once you hit the new UTC day, it counts as a new activation. That really works in your favor as an activator if your goal is to complete a valid activation (with ten contacts) and you’ve enough time to do that before the UTC rollover. If you time it all correctly, you could activate double the parks with a minimum of 20 contacts (split 10/10). In my case, that would mean a total of four parks activated in one evening (since this was a two-fer).
I decided fitting in an activation prior to the UTC rollover simply wasn’t worth the rush.
Once I arrived on-site, however, I was already changing my mind.
I started my activation video, deployed the MC-750, and looked at my watch. I had roughly 15 minutes before the UTC rollover.
It would be tight, but I decided to give it a go and try logging ten contacts before 18:59:59 local (or 23:59:59 UTC).
If I couldn’t log ten before the UTC day, who cares!? It would be a fun challenge for sure, but I wasn’t going to cry if I couldn’t gather enough contacts for a valid activation.
There was another factor, too: operating 80 meters with a 17′ loaded vertical isn’t exactly “efficient.” My theory, though? It doesn’t need to be efficient. It’s crazy portable, convenient, and as a POTA activator, I only need enough performance to get the job done.
Time to hit the air!
Radio Gear:
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The Sunday of President’s Day weekend, I was supposed to camp overnight at Reed Bingham State Park and pursue two more activations for my 2024 goal of 60 new-to-me parks. However,the Wednesday evening prior, I sustained an injury to my right hand which happens to be my sending hand. The injury was serious enough that I rescheduled that trip for June and, for my bi-weekly QSO with my code buddy Caryn KD2GUT, I sent on the paddle with my left-hand which turned out better than I expected.
Since I did not go out of town as planned, my son Sean attended his bi-monthly Dungeons and Dragons (D&D) meeting Sunday afternoon. Another code buddy, Gary K4IIG, suggested that while I waited for Sean, I should consider activating. The weather was unpleasantly chilly and overcast so I opted against an activation but did want to try out my new antenna, the Chelegance MC-750. I knew I needed another vertical for my POTA kit and it came highly recommended by several other hams.
Not welcoming weather!
After dropping off Sean, I headed to Skidaway Island, a 30-minute drive. Seven hundred acres of the north end of the island belong to the Skidaway Institute of Oceanography, part of the University of Georgia. The site is for salt marsh research and houses the administrative offices for Gray’s Reef National Marine Sanctuary. The land is open to the public for daytime hiking and wildlife viewing. In fact, Daisy and I have walked there on several occasions. The habitat is typical coastal maritime forest with live oaks, Spanish moss, and palmettos along with some more open areas populated by pine trees.
Daisy and I chose the open field outside the institute at which to park and set up the new antenna. We were not the only ones using the field that afternoon despite the weather. While there, several other dog owners showed up to let their pups run and play in the field.
I read the simple three-page instructional PDF from Chelegance’s website and thought I had a good idea of how to set up the MC-750. However, I had not read any instructions about using it with the tripod accessory. I knew the bottom spike needed to be removed but couldn’t get it out with my bare hands. This is why I carry a Wave+ Leatherman [QRPer affiliate link] with me! I rarely use it but when I need it, I REALLY need it. Soon the spike was off and I was ready to set up the antenna.
True to what I heard, the Chelegance vertical is easy to set up. You screw together a few sections, plug in the four radials at the bottom, select your band and extend the whip to the location marked on it, then screw the whip on. Viola! Yes, it was that easy!
Usually my son’s D&D sessions last 3.5-4 hours so I figured I would log onto the Straight Key Century Club (SKCC) sked page and see if I could scare up some QSOs as I work toward the rank of Senator. Yes, even POTA Babes do non-POTA things. For me, my non-POTA CW activities are code buddy and SKCC-related QSOs.
SKCC is a wonderful organization of more than 28,000 ops from all over the world. To pursue their awards and ranks, one has to use a mechanical (straight, cootie, or bug) key though anyone can participate in their sprints or other events to join in the fun (just send “none” for the SKCC number if using a paddle). It is because of them that I learned to use a straight key and cootie (my favorite key) and am now learning to use a bug.
I decided to start with 20 meters and moved the whip to the 14 MHz mark. Then I remembered my code buddy Caryn KD2GUT mentioning something about a contest going on this weekend. I set up my laptop and checked the Reverse Beacon Network online graph by HA8TKS. WHOA! That band was chock full of signals. As I was using my KX2 and was therefore QRP, I knew there was no point calling CQ on that band.
The SKCC sked page is a wonderful resource. You can private message ops for a QSO or just to say hi! If calling CQ, you can post your frequency and on what you are working. I claimed 18.088 and noted I was working toward Senator, using QRP and slower ops were welcome. (I like to slow down for newer ops or those who are in an ambling frame of mind as many other ops slowed down for me when I entered the hobby.)
I spent about 10 minutes calling CQ and queried on the general section of the sked page if anyone was hearing me as I had a new antenna. That is when Jim N0IPA from Colorado answered my call. Jim, like me, is learning to use the bug. I suspect he is working on the Triple Key Award, too. To achieve this award, an op has to have 100 unique SKCC-member QSOs each with a straight key, cootie, and bug. I happened to be Jim’s first bug QSO! The standard SKCC exchange is RST, QTH, name, and SKCC number and it wasn’t long before we had each other in our log.
About ten minutes later, Jacob N3VH answered my call. He is located in New Jersey and said by the end of our QSO, my RST was a 559. Both Jacob’s and Jim’s QSOs counted toward my Senator progress putting me at 48 out 200 QSOs left to earn my toga!
Unfortunately, my son’s D&D session ended earlier than expected which meant it was time for this POTA Babe to call QRT. The short time was well worth it as I now felt more comfortable with the new antenna and was 2 QSOs closer to earning the rank of Senator with SKCC. Plus, I got on the air with QRP for a non-POTA exchange which is unusual for me. I also have a place I can visit (if the weather cooperates) two weeks from now for more non-POTA QRP work. The fun with ham radio never stops, does it?!
And for those of you wondering how my progress with my 2024 POTA goal is coming along, you’ll find out soon when I attempt to activate park #17 on that journey. Stay tuned…
In late December 2023, I received a package from Jesse at JNCRadio/Chelegance. It was their new MC-599 portable dipole antenna. They sent it—full disclaimer: at no cost to me—for evaluation, but shortly after receiving it, life got crazy and I was delayed in taking it to the field.
Fast-forward to February, and I was eager to take it to the field and see how it might perform. On February 5, 2024, a nice window of opportunity opened in the afternoon while one of my daughters was rehearsing A Midsummer Night’s Dream with her cast. Pisgah National Forest and Game Land were a 20-minute drive from her meeting site, so I headed there to deploy this new antenna.
The JNCRADIO MC-599
On-site, I pulled out the two main components of the MC-599 dipole system: the bespoke padded bag holding the antenna and the portable mast.
I knew the basics about assembling the MC-599 because I had watched a video on the Chelegance website that morning.
However, this was the very first time I had deployed the MC-599. I had never even removed any of the antenna components from the padded bag.
With this antenna, it’s best to have an open area for the two sides of the dipole (two telescoping whips) to fully extend without touching tree branches, etc. I had one particular picnic site in mind at the roadside picnic area I chose, but a couple was having a picnic there when I arrived. I waited to see if they might be leaving soon, but they weren’t, so I chose a site I had used before, even though it was flanked by trees.
Assembly was easy: I simply attached the center of the dipole to the 13′ mast, then attached the two telescoping whips to either side and extended them to the 20M position silkscreened on the whip (identical to the MC-750 vertical markings—see below).
Next, you simply attach your coax to the center of the dipole, then extend the mast all the way up.
I had to avoid touching tree branches, but it actually fit quite easily into this small space.
Since it was a bit breezy, I used some line to guy the mast. Ideally, you’d want a minimum of three guying points, but I only had two lines with me, so I made do, and it worked fine—the antenna was stable.
Next, I set up my radio: the Yaesu FT-818ND. Since the MC-599 was, in theory, resonant, I didn’t need an ATU for a match.
I turned on the FT-818 and discovered that the SWR was a perfect 1:1. Amazing.
I suppose I shouldn’t have been surprised because my Chelegance MC-750 is always perfectly resonant (without needing a transformer) simply following the whip markings for guidance.
I should note here that the MC-599 can handle up to 200 Watts PEP—I was pushing 5-6 Watts. Also, the frequency range using the whips is from 20-6 meters. Chelegance also includes two 7 MHz wire elements that can be deployed in an inverted vee shape to play radio on the 40-meter band. It’s an efficient system and has many fewer components than a Buddipole systems I’ve used in the past.
Gear:
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Keep in mind that my POTA site was in a deep valley, flanked by high ridge lines–I wasn’t sure what to expect as I hopped on the air.
I started calling CQ POTA and the first station I heard was DL1OK operating in Spain as EA8/DL1OK. Logging Dmitrij was a good sign indeed for this portable dipole!
Stations kept flowing in. I worked my first ten contacts in ten minutes.
I continued working stations in a continuous pileup until I ran out of time. I ended up logging a total of 46 contact all within 50 minutes. I did spend a few extra minutes (as I always do) trying to pull out weak stations and slower code stations.
What fun!
QSO Map
Here’s what this five-watt activation looked like when plotted out on a QSO Map.
Note that this map does not include my contact with EA8/DL1OK in Spain:
Activation Video
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’ve got to admit: the MC-599 made a great first impression.
As with the MC-750, I’m most impressed with the build quality. The components are all sturdy and nicely machined. The padded case was custom made to hold the MC-599 and its components. Everything fits together as it should and—again—was resonant when deployed according to the whip markings.
Even on this inaugural deployment, it didn’t take long to set up. The next time I deploy it, it will go even faster. Packing it up afterward (as you can see in the video) went very quickly.
Keep in mind: the MC-599 is a low-impact, high-profile antenna.
If you’re at a site that doesn’t allow antennas in trees, the MC-599 could be an excellent option. Other than using optional guy lines that would require tent stakes in the ground, it would have no impact on park grounds.
I love the fact that the MC-599 is self-supporting. This would be an absolutely brilliant antenna to use at parks with wide-open spaces and few trees for support.
That said, it is not a stealthy antenna. In fact, portable dipole antennas are some of the most conspicuous portable antennas you could deploy. They’re maybe slightly less conspicuous than a hex beam or Yagi. Even though I was cloaked by a few trees, the couple that was occupying the picnic site I had hoped to use couldn’t help but stop by on their way out and ask what it was I was doing. I bet if I had been using a wire antenna, they wouldn’t have even seen it.
I would always ask permission before setting up an antenna like the MC-599 at, say, a small historic site or urban park.
I could also see using the MC-599 for SOTA (Summits On The Air), but primarily on summits that are either drive-up, or where the hike is minimal. The aluminum alloy mast is lightweight for its size, but it’s quite large to consider taking on an extended hike. However, for a nice drive-up summit, I imagine you could work some serious DX. Just bring a few guy lines in case it’s windy.
I do think the MC-599 would make for a great Field Day antenna. Since it can handle up to 200W PEP and is easy to lower and switch bands, it would be a brilliant portable option for those operating a multi-band 100W rig.
But obviously? It’s an exceptional performer with QRP power. It’s hard to beat a dipole even when it’s only 13′ off the ground.
Thank you
Thank you for joining me on this fun activation!
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.
Many thanks to Scott (KK4Z) who shares the following post from his blog KK4Z.com:
K4SWL+ Antenna
by Scott (KK4Z)
On a recent post on QRPER.com, Teri KO4WFP was at a park in Florida that did not allow wires (or anything else) in their trees. Many POTA activators use End Fed Half Wave antennas which usually require one end in a tree. While it doesn’t happen at all parks, not being able to hoist your antenna could bust an activation.
I realized this may happen to me even though Georgia appears to be pretty lenient when it comes to such matters, I decided to switch to a park friendly antenna. I have been a fan of QRPER.com for quite some time and occasionally Thomas will repost something from my humble blog. That being said, it was K4SWL that got me started using a random wire antenna. My basis for my antenna was his speaker wire antenna which was a 28.5’ vertical antenna with a 17’ counterpoise. I used it a few times in that configuration and then started to modify it. I call this antenna my K4SWL+.
Some of the differences are I use a push-up pole to get the antenna in the air and at the base I use a 9:1 UnUn and a 1:1 Choke to keep RF out of the radio. A random wire antenna can feed RF back into the coax.
The wire is 14 ga. coated flex weave from The Wireman. This was left over wire from some other antenna projects. When I started this project I was using 22-24 ga. coated wire from SOTABeams but realizing there was no need to save weight, used the heavier wire. This allows me to dual purpose the antenna both for FunComm and EmComm. The insulator at the top is 3D printed with my call-sign and the base is U-type lugs. I find these are the best as I do not have to take the nut off of the antenna studs and if pulled hard will come loose instead of damaging the UnUn. I connect the antenna to the top of the push-up pole with a small Nite-eze “S-biner” size 1.
The 9:1 UnUn comes from Palomar Engineering. I have already created a blog post about how to build it and it can be found here: https://kk4z.com/2022/05/28/91-unun-qro/
Part of this blog post was to bring the different components together into one blog post.
I made two different types but I found the second works much better.
The project is pretty easy, the only caveat is to pay attention to what wire goes where. Putting it all together, you need a push-up pole, a Flag holder and maybe a trailer hitch extender. I will provide links below. The Flag Pole holder I used was not available so the link I used is a probable substitute. I have a trailer hitch on both my truck and my camper, When I pull into a campsite I have a choice of which hitch to use to keep my antenna clear from the trees. With the antenna up, I wrap the antenna wire around the push-up pole from tip to base, to prevent the wire from sagging near the tip. I attach the UnUn and choke to the mast with Stretch Velcro Straps. With my antenna up I have park employees drive by me all day along. Most of the time we exchange a friendly wave and occasionally one will stop by for a chat. I have had zero issues with this antenna at any of the parks I have visited.
How does it play? It has pretty much been a main antenna for just about all of my POTA activations. You can go back through my blog post and see what equipment I used with the antenna and the accompanying QSOMap. You do need an antenna tuner with this antenna and I typically use an LDG Z-11 Pro which I’ve had for 15+ years. The antenna tunes up from 80 to 6 meters and I have run the power as high as 65 watts. I normally run 10-35 watts depending on band conditions. I have tried it on 160 meters and while I can get a match, I don’t think much RF is leaving the antenna. I’ve made a few contact with it on 160. If you like to work 160 meters during a POTA activation, I suggest a Chameleon EmComm II with a 60’ antenna and a 50’ counterpoise. I run it as an inverted L with the apex about 20’ up my push-up pole and the end sloping down to something not a tree. Last time I tied it to the lantern stand at the campsite. It worked pretty well and I was able to make contacts on 160.
If you’re looking for an antenna that you can set up almost anywhere, with little or no hassles, take a look at this one. Don’t forget to check out the short video above. 73 — Scott
Today’s activation of the Presidio of San Francisco National Historic Site (K-7889) was pretty standard for a mid-winter POTA outing. Normally, I wouldn’t bother to write it up on this blog. After coming here 72 times there is not much new to say about it. Nevertheless, maybe somebody will find value in this field report.
Even though the weather was dry this afternoon, the radio operating began in the car where I used the FT-818 to net 14 contacts on 17 meters. I must admit being warm while doing a POTA activation is not bad!
The Bencher is a breeze to operate on the center console.
After a while, the calls started to dry up so I extended the antenna fully to get on 20 meters, but the best SWR I could get was 3:1. I suppose the lack of good bonding of the coax shield to the car body, which I’ve read about in other blog posts on qrper.com, was responsible for the less than optimal antenna match.
After taking down the badly matched roof mount antenna , I flipped the car around and backed into the parking space to set up my usual 20 meter station on the trunk lid with the antenna clamped to a steel post.
The trunk lid is where I usually operate from when at this park.
At the same time, I switched radios to the Mountain Topper MTR-4B. Previously the current draw of the FT-818 had dropped the battery voltage to 12.6v, but with the lighter load of the MTR, the voltage rebounded above 13v. The MTR-4b is designed to accept 13v, something the other radios in the MTR series are not recommended for. However the SWR in this antenna configuration was 1.0 to 1 so I felt okay to run the radio at the full 5 watts with the higher voltage.
The Wolf River coil provides a good match on 40 meters.
Unfortunately, 20 meters wasn’t performing all that great, yielding a mere four contacts. The POTA website showed several JA’s activating parks on 40 meters, so I added the Wolf River coil to the base of the antenna in hopes of hearing them. Alas, no copy, so I put out a few CQ POTA calls of my own on 7.062 MHz. W6OOD responded from Southern California, but my report was not particularly strong. And, with the light fading I decided to call it a day.
It’s funny, but true. The World of Amatuer Radio is flat!
We often think we know the direction to a DX contact, but we seldom do. Especially at distances beyond 1,000 miles. Therein lies the misconception in our DX radio reality.
We assume this spherical, oblate ellipsoid, we call Earth, as round. In fact, it bulges at the equator, flattening the poles. Ergo, our sense of direction is wonky… Lets fix that. Here’s a link. https://ns6t.net/azimuth/azimuth.html
Here is a copy of my Azimuthal Map from DN13tq:
The center of my universe is Boise, Idaho, specifically DN13tq. Using the NS6T.net website, you too can enter your Maidenhead coordinates and see your radio world in a whole new light. Download your own Azimuthal Map and see the World as flat.
Europe, for me, is not East. If I had a log periodic beam, I’d be talking to Cape Town South Africa at 90 degrees east. Europe (for me) is 30 degrees NNE from my QTH. As a QRP field operator, I should orient whatever gain, in whatever field antenna I may have, accordingly. Just saying… The World of Amatuer Radio is flat!
So get properly oriented, and go out and discovery New Worlds.
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.
The Mountain Topper MTR-5B I acquired earlier this year.
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.
I recently decided that I would operate portable during the upcoming ARRL 10 Meter Contest and would combine this operation with a pair of Parks on the Air (POTA) activations, one on the Saturday of the contest and one on Sunday. While putting together my field station for this, I realized I wanted to see how lossy my RG-58 and RG-316 feedline cables were on 10m. Yes, I could have resorted to online charts of feedline losses, and I know that the RG-316 is lossier than the RG-58, but I thought it would be fun and more enlightening to make actual measurements, to empirically determine the losses in my particular coaxial cables.
The two coaxial cables in question are both 25′ in length and both are equipped with BNC male connectors on each end. The RG-58 cable is a high-quality cable that was originally manufactured to be a 10Base2 ethernet cable, but it’s probably now over twenty years old. The RG-316 cable was recently purchased from Tufteln (link) and includes an RF choke near one end.
To make my measurements, I used my Elecraft KX2 (link) to generate RF into an Elecraft DL1 dummy load with RF detector (link), using a digital multimeter to measure the voltage at the DL1’s measurement points. I used the formula that came with my DL1 assembly instructions to calculate the measured wattage:
P = (((V x 1.414) + 0.15))^2)/50
I made measurements in the CW portion of the 10, 15, 20, 40, and 80m bands, with the KX2 set at 5 Watts output.
My first set of measurements was made with the DL1 connected directly to the KX2’s antenna jack using a BNC union:
Direct (no feedline)
Band
Volts
Watts
10
11.62
5.498
15
11.59
5.470
20
11.61
5.489
40
11.63
5.508
80
11.63
5.508
My immediate observation was that the KX2 appears to be generating more than 5w when it is set to be producing 5w but also that the KX2 output is essentially same from 10m through 80m.
My second set of measurements was made with the DL1 connected to the KX2 through the RG-58 cable:
Direct
RG-58
Band
Watts
Watts
10
5.498
4.809
15
5.470
4.844
20
5.489
5.004
40
5.508
5.184
80
5.508
5.276
My third set of measurements was made with the DL1 connected to the KX2 through the RG-316 cable:
Direct
RG-316
Band
Watts
Watts
10
5.498
4.190
15
5.470
4.322
20
5.489
4.507
40
5.508
4.774
80
5.508
4.959
I was pleased to see to see that both the RG-58 and RG-316 behaved as I expected them to: the loss increased with increasing frequency.
Using the magic of MS-Excel, I created a table of Loss in Watts for both cables, relative to direct connection and to each other:
Direct
Difference (Loss) (Watts)
Band
Watts
RG-58 vs
direct
RG-316 vs
direct
RG-316 vs
RG-58
10
5.498
0.690
1.309
0.619
15
5.470
0.626
1.148
0.522
20
5.489
0.485
0.982
0.497
40
5.508
0.324
0.734
0.410
80
5.508
0.232
0.549
0.317
In looking at this table, it was immediately obvious that RG-316 is much lossier than the RG-58, particularly on 10m. By looking at the row for 10m, one can see that I am losing nearly 0.7 watts in the RG-58 but I am losing over 1.3 watts in the RG-316.
For completeness, I added columns for Loss in dB to the spreadsheet:
Difference (Loss) (dB)
Band
RG-58 vs direct
RG-316 vs direct
RG-316 vs RG-58
10
0.582
1.180
0.598
15
0.528
1.023
0.495
20
0.402
0.856
0.454
40
0.263
0.621
0.358
80
0.187
0.456
0.269
This exercise showed me that for my upcoming ARRL 10 Meter Contest POTA outings, I would do best by connecting my antenna directly to my transceiver, if possible, without using either coaxial feedline. If conditions at the operating site require me to use feedline, I will chose the RG-58 over the RG-316.
The tables also tell me that RG-316 is pretty lossy regardless of the band; for my regular field operating, unless I’m planning to do bicycle- or pedestrian-portable operations where weight and bulk is a consideration, I’ll carry RG-58 instead of RG-316. (I purchased the RG-316 specifically for bicycle- and pedestrian-portable operations, and I plan to continue to use the RG-316 for those applications.)
At some point, I will repeat this exercise with RG-8X, a feedline that is very close in size to RG-58, is less lossy, but is also heavier and stiffer.
Testing the Diamond RHM-8B portable screwdriver antenna
By Steve (MW0SAW)
I have seen many amazing K4SWL SPOTA pileups on YouTube using the AX1 antenna and the extension coil. I have fancied trying a small walkie talkie style whip antenna for a while now.
I have a AX1 and KX2, but my Yaesu FT-818 was the radio with a fully charged battery. So I pulled out The Diamond RHM-8B, an antenna I purchased a while ago but never used in the field. It has a BNC fitting and you tune the antenna by sliding the coil up and down for loudest signal and best SWR. They make one very chunky walkie talkie together! Diamond products do have a fantastic air of quality about their construction.
Radio conditions weren’t great, and bands were busy being the weekend of the CQ WW CW contest. So decided to go the my nearest summit that’s amount 12mins in the car and about a 25mins hike up. This was GW/SW-034 Garth Hill. On a clear day you can see out over the Bristol Channel into England, but mist/fog were the order of the day.
I wore the FT-818 and rubber duckie around my neck with the neck strap for a couple of 2m FM contacts, before setting up on 40m SSB sitting on the ground. Without a tablet or chair with me I found it most comfortable to support the radio between my knees.
I was really pleased to get 9 QSOs in the log, some 59 reports, some difficult contacts. Moving on to CW I managed another 8 QSOs with an S2S into Germany.
All the QSOs were UK and mainland Europe, but I was more than happy with the haul for such a small antenna.
So conclusion about the Diamond QRP antenna.
Can you qualify a SOTA summit on a short 1.5m whip antenna? Absolutely, no sweat!
Does it work as well as a full size wire antenna? Of course not. Nowhere close.
However, its makes such a great rapid deploy, ultra packable option with the Yaesu. Not quite as small as a AX1 but you have the bonus of not requiring a tuner. Definitely something for a travel bag if you own a FT-817/818.
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I’m an avid POTA activator and wanted to try an experiment to see if I could complete an activation using just the Elecraft KX3 & AX1 on 40 & 20m SSB. I’ve seen others do it on CW but not on SSB. My CW learning is not going well by the way.
It’s a good thing I had brought along my Tuftln EFHW and telescopic carbon fiber fishing pole as well because it saved the day which allowed me to complete the activation. When activating make sure to have a backup plan, so far I have no incomplete activations.
