Many thanks to Adam (BD6CR) who shares the following guest post about his latest project:
From Open Source Project ADX to Kit ADX-S
by Adam (BD6CR)
BD6CR @ CRKits.COM
Original Design: WB2CBA
Modification and Kitting: BD6CR
I knew Barb, WB2CBA from his uSDX design a few years ago and I introduced both DL2MAN and his designs in my blog. So, when I came across the ADX – Arduino Digital Xcvr a few months ago, I immediately ordered both the ADX (through hole) and the ADX UNO (surface mount) PCB samples.
I started building the ADX UNO and put it in a dental floss case and made a few contacts on park bench. However, the soldering is too much for my eyesight. So, I turned back to the ADX because I don’t need to solder any SMD parts, since both the M328P and SI5351 are module based. I could build the project in 3 hours and it worked the first time.
However, I felt unsatisfied with the strong BCI since the CD2003 radio receiver chip was connected as a direct conversion receiver. JE1RAV mentioned in his QP-7C modification project that he tried JA9TTT’s idea to build a superhet SSB receiver with the TA2003 or CD2003, so I tried and it worked very well. I have decided to name the new circuit as ADX-S, where S stands for Superhet.
I shared the great news with Barb and he encouraged me to carry the flag to make it a kit, since my design D4D was his first digital radio and he loved it.
My hardware modification can be outlined in this schematic. I have added an FL1, PFB455JR ceramic filter by Murata and a C25 coupling capacitor from CLK2 of SI5351 module. The RX audio comes from pin 11 instead of pin 4.
Many thanks to Keith (KY4KK) who shares the following report:
Extreme QRP – Testing the AX1 with WSPR and 20mW
by Keith (KY4KK)
Thomas, thanks for all of your activation videos related to the Elecraft AX1 antenna. I ordered one the day you announced the package deal, and it arrived in less than a week. I’ve activated a few parks with it already (20m SSB). Like you and many others, I’m impressed.
About a year ago, a friend (NG4S) loaned me his pair of WSPR transmitters and suggested that I explore building and comparing antennas. I’ve been hooked on antennas of all kinds and WSPR since then.
I began doing WSPR tests on the AX1 the day after it arrived. With two transmitters set to the same frequency and power output, you can do direct comparisons between two antennas under identical propagation conditions.
I’ve already done a couple of comparisons between the AX1 and other commercial antennas. But I think the test I just completed might be of particular interest because it pits the AX1 against an antenna I’ve seen you use many times – a 28.5’ end fed with a 28.5’ counterpoise. I used 24 AWG silicone insulated wire. The end of the radiator was placed on a 19’5” telescoping fishing pole. This is my preferred POTA mast when I can’t use a tall tree.
I spent some time trying to control other variables so that the only significant difference during the test would be the antennas themselves.
For example, the SOTA Beam WSPRLite Classic transmitters don’t have an ATU. So, I had to make the antennas resonant on the 20-meter WSPR frequency of 14.097 MHz. For the AX1, Thomas’ videos helped a lot. I used a clip-on capacitance hat and adjusted the counterpoise to 15’ 2”. This gave me an SWR of 1.17:1. For the end fed, I tried the two UNUN’s I had available and settled on the 49:1, which got me the closest (2.2:1). I then used a manual tuner to achieve an SWR of 1.29:1.
I also wanted to deal with the difference in power output between the two transmitters. Although they’re identical, and both set to 20 milliwatts, there is no way to ensure both are actually producing that output level. Based on tests by NG4S, one of the transmitters runs at 19 milliwatts. The other actually outputs 27 milliwatts. So, my plan was to run the test for 48 hours. At the end of 24 hours, I would switch the transmitters (and callsigns) so that both antennas would benefit (relatively equally) from one of the transmitters being stronger.
At the end of Day 1, I reviewed the data from the two transmitters on dxplorer.net/wspr. The end fed averaged a 5.7 dB gain over the AX1 based on reports from receiving stations that spotted both transmitters in the same 10-minute block (simultaneous spots).
On Day 1, the stronger transmitter was on the end fed. The maps below are from WSPR.rocks.
Many thanks to Conrad (N2YCH) who shares the following field report:
AX1 Test using American Radio Supply AM-801 Window Mount: POTA Activation at Stuart B. McKinney Wildlife Refuge, K-0228
February 19, 2023
By: Conrad Trautmann (N2YCH)
If you’ve been reading the posts here on QRPer.com lately, you probably already know that the Elecraft AX1 has proven to be an excellent antenna for POTA activations for CW, SSB and Digital modes.
Personally, I used it for a New York City POTA rove I did at the end of 2022 and was able to activate four parks in one day all over Manhattan.
Recently, Alan, W2AEW contributed a story to QRPer.com detailing how he used a window bracket he constructed with an AX1 to do a CW park activation from his car. I’ve actually done a few digital activations from the car using the AX1, however, I used the tripod with the Elecraft tripod adapter and ran coax to it out the window and draped the counterpoise down the hood or trunk. This has worked well except for windy days where it would blow over. I was intrigued by the possibility of using the window mount and a number of the commenters to Alan’s post suggested sources for these types of mounts. I ended up ordering an AM-801 from American Radio Supply.
Since the AX1 depends on a counterpoise wire to operate properly, the first thing I did after receiving the AM-801 mount was to drill a hole in the base for a screw and a wing nut. The base is painted black, so I got my continuity meter out to double check that the screw was making a good ground, which it was. I had to bend the mount up slightly for the antenna to be vertical, since my Jeep windows don’t have much of an angle to them. I’m sure it would be just right for most cars.
Because I receive so many tips from readers here on QRPer, I wanted way to share them in a concise newsletter format. To that end, welcome to QRPer Notes, a collection of links to interesting stories and tips making waves in the world of radio!
PSK-31 on the Elecraft KX2
Many thanks to Tony (K2MO) who writes:
I have no doubt that you’ve tried this in the field, but thought I’d send along a video I posted on working PSK31 using the CW-to-Data feature on the KX series rigs.
Great job on the latest TR-45 vids!
73 Tony -K2MO
Thank you, Tony!
DX and Travels of Lloyd & Iris Colvin
Many thanks to Don (W7SSB) who shares an article he has written for the Sierra Nevada Amateur Radio Club Newsletter. His article focuses on the lives of DXers and world travelers Lloyd & Iris Colvin.
Don’s article begins on page 10, but there are many others to enjoy in this newsletter as well!
Many thanks to Conrad (N2YCH) who shares the following field report:
Field Report :POTA Activation K-0228, Stuart B. McKinney National Wildlife Refuge, Great Meadows Unit
by Conrad (N2YCH)
January 21, 2023
Parks On the Air’s Support Your Parks weekend event for winter 2023 is the third full weekend in January and I found myself without my Jeep. I sold my ten-year-old Jeep Wrangler and my new Jeep wasn’t due to be delivered until the following week, leaving me without my “POTA activation vehicle”. I ended up borrowing my XYL’s MINI Countryman to activate K-0228, but let’s face it, a MINI is not a Jeep. It didn’t have all of my “stuff” in it. I needed to get creative about what to bring along with me that would fit easily in the MINI, yet work well enough to activate the park.
I started with my backpack kit which contains an Elecraft KX3, battery, Signalink and computer (for FT8 and logging).
It includes everything I need to transmit and it’s easy to toss in the car. I just needed to decide on what antenna to use. Since it’s winter here in Connecticut and pretty cold outside, this would be an “in-the-car” activation and without the Jeep, my antenna options were limited. I could have brought my Sotabeams Tac-Mini which could fly my PackTenna EFHW up about 20’. However, anchoring the mast would be a challenge in the cold weather. In the end, I decided to bring my Buddipole tripod and nested mast, which are compact and fit in a small bag which fit right in the passenger seat. Continue reading MINI Portable: Conrad’s POTA field report from Stuart B. McKinney National Wildlife Refuge→
Many thanks to Conrad (N2YCH) who shares the following field report:
QRP-Labs QDX Field Report
K-1716, Silver Sands State Park, Milford, Connecticut
January 13, 2023
By: Conrad Trautmann, N2YCH
A digital mode multiband transceiver for $69? Yes! QRP Labs has the QDX kit available for $69 US. Add $20 if you would like a very nice black anodized aluminum case to mount it in and if you want it assembled and tested add another $45. Visit the QRP Labs web site for all of the details (QDX 4-band 5W Digi transceiver (qrp-labs.com)
How well can a $69 digital transceiver work? Read on…
I ordered my QDX kit back in May 2022. It arrived in June, I assembled it and ran some tests at home. It worked well on FT8 into my home antennas. It interfaces nicely with WSJT-X and I liked the idea of using a low power transceiver to band hop on WSPR. My QDX is an early four band version, which does 20, 30, 40 & 80 meters. I set it to band hop on all four bands not remembering that my multiband offset center fed dipole is not resonant on 30 meters. Since the QDX does not have a tuner, it didn’t like the higher reflected power of a two minute long WSPR transmission into a bad load and smoke resulted. I was fortunate that the failure was isolated to the RF power amplifier transistors and replacing those got me running again. This was my own fault, not the transceiver. Now, it band hops on 20, 40 and 80 meters with no issues, I eliminated 30 meters from the hop schedule.
I share this important story at the beginning of my field report as a warning to anyone considering using a QDX to be very careful when connecting an antenna to it. Since the QDX does not have an internal antenna tuner, you either need a resonant antenna or must use an external tuner to provide a 50 ohm load with low SWR to the QDX. The QRP Labs groups.io site has a number of posts from users with different tuner suggestions.
Now comes the fun part. I visited Silver Sands State Park, K-1716, located on Long Island sound in Milford, CT on January 13, 2023 in the afternoon. While it was Friday the 13th, I had nothing but good luck. Knowing I would be running QRP power, I decided to use what I consider to be my best 20 meter antenna. It’s a modified version of a Buddipole, which I call my “no coil” Buddipole dipole. I use a Buddipole VersaTee mounted to a WILL-BURT Hurry Up mast, which is a push up mast that extends to about 25’ high. The dipole consists of two Buddipole 32” accessory arms, one for each side of the VersaTee and two MFJ 17’ telescoping whips, extended to just about 17.5’. This provides a very broad bandwidth and low SWR on 20 meters. See the screen shot of my antenna sweep from the RigExpert analyzer below.
Here’s a photo of the antenna in the air.
The temperature on this January day was a mild 55 degrees so I was able to set up my equipment in the back of my Jeep. Here’s everything I needed to do the activation. Since the antenna is resonant, I did not use a tuner.
My iPhone gives you an idea of just how big the QDX is, which is sitting just to the right of it. There are only three connections needed, the antenna cable, a 12V power cable and the USB cable. I was using my Bioenno 9ah battery for power. I brought the Bird Model 43 with a 25 watt element in it to monitor the output power and also to measure the reflected power, which barely even nudged the meter. It was effectively zero watts reflected. In the photo above, I was in a transmit cycle and you can see the power meter just a touch above 5 watts. On the computer, you can see a mini pile-up of six hunters in the queue. One thing to note about the QDX is that you can’t adjust the power by lowering the PWR slider in WSJT-X. It’s recommended to leave that at maximum. The way to adjust output power is to adjust the power supply voltage. In this case, the Bioenno had a full charge, so the radio was running full power.
I began the activation without spotting myself, just to see who’d hear me. Here’s a map of the pskreporter showing my spots.
I eventually spotted myself so hunters would know what park I was at. I was amazed that during my activation, I never ran dry or had to call CQ POTA, there was a steady stream of hunters the entire time. The QDX does a fine job receiving, here’s a screenshot of WSJT-X including the waterfall to show what it was receiving.
So, how did the $69 radio do? In a one hour and 17 minute activation, I completed 46 FT8 QSO’s. Here’s my coverage map.
I managed to complete three park to park QSO’s, too. One park called me and I called the other two who heard me and answered. I use JTAlert which helps me keep track of the order of who called. I always try to answer the hunters in the order they called me. I’ve set up a Directed CQ alert in JTAlert for anyone calling “CQ POTA” which helps me to see who else is at a park while I’m activating. If I’m able to contact them, I use the POTA spot list to include their park number in the SIG_INFO field of my log, which is N3FJP. N3FJP is handy to use since I start a new log for each activation and I’ve configured it to upload to LOTW and QRZ when I’m done for the day.
Another thing worth noting is that there is no speaker on the QDX. I’m one of those digital operators who actually listens to the cycles while I’m on the air. It provides a certain cadence to hear each cycle go by so you know what to be looking at or clicking on and when. With no sound coming out of the QDX, it forces you to find that cadence by looking at the computer screen. For me, it means watching the receive audio levels and the progress bar to see if I’m transmitting or receiving. The QDX does have a single red LED on the front panel that will flash during transmit cycles, which is also a helpful indicator.
I’d say the results shown here speak for themselves. I had a steady stream of hunters, I had just one or two QSO’s that needed a second RR73 to confirm and the coverage was as good as most activations I’ve done with more expensive radios and more power. Despite the self-inflicted hiccup I experienced at the beginning, I’d say that If you’re looking to try activating digital for Parks On The Air or even for your home, the QDX certainly works very well and provides a lot of value for the money.
Many thanks to Conrad (N2YCH) who shares the following field report:
New York City Park Rove, December 30, 2022
Conrad Trautmann, N2YCH
After being bitten by the Parks On The Air (POTA) bug, I became an activator in early 2022. I was hooked. Digital, and specifically FT8 & FT4, is the mode I prefer. A lot of experimentation ensued until I was able to refine my POTA setup to an Icom IC-7300 powered by a Bioenno 20ah battery mounted in a four rack unit Gator case and a Buddipole dipole antenna on a push up mast.
As a radio broadcast engineer by trade, I was very focused on maximizing performance and coverage and after much refinement and trying different things, I feel like my POTA kit performs well. I’ve made contacts as far away as Indonesia, Japan and Israel using the POTA setup in a park… so mission accomplished.
The POTA kit above is not something I can easily take with me on a business trip however, especially by air, so I turned my sites to a Xiegu G90 and various end fed half wave antennas and fiberglass masts and more Buddipole parts to pack into my carry-on luggage. Now I could activate parks wherever I could fly to and I’ve completed successful activations in Wisconsin and Georgia.
Still, I needed to pack a second bag and check the luggage to do these trips. What I really wanted was something I could carry on the plane with me.
I knew I had to change my point of view on what I could achieve using a portable kit. A small radio and antenna wasn’t going to get me contacts in Indonesia, but I could transmit far enough to have someone hear me and get my ten contacts to activate a park. Researching my options online constantly brought me to videos and blog posts here on QRPer.com. Thomas loves his Elecraft KX2 and in a few field report videos he demonstrates an Elecraft AX1 antenna connected directly to the radio for some fast CW POTA activations. This setup was appealing because of the size and he always has a successful activation.
I researched the Elecraft options and the KX3 seemed like the right radio for my digital activations. It has a DATA mode, it can run split operation, it’s got a wideband filter setting and while Elecraft only recommends 5 watts for data modes, it can do up to 10 watts. I managed to find and purchase one gently used on eBay.
I installed the Pro Audio Engineering Kx32 aftermarket heat sink to be sure I protected the final output transistors from overheating and use a Signalink model USB SLUSBKX3 as a sound card interface to the computer. The Signalink can key the radio using the audio keying feature, but I chose to use the Elecraft KXUSB cable to use CAT control and let WSJT-X key it instead. It also allows WSJT-X to read and control the radio’s frequency for easy band changes. I have a Bioenno BLF-1209A 9Ah battery to run it rather than use the internal batteries and I haven’t come close to running the battery out on an activation yet.
Then I bought the Elecraft AX1 antenna with the 40 meter AXE1 optional antenna extender and the AXT1 tripod adapter. It is tiny. There’s really no other way to describe it. It’s a little, baby antenna. Fully extended, it is about four feet tall. I was highly skeptical of how this might perform given its size. I’m using a 25’ Buddipole RG-58 A/U 50 ohm MILSPEC-17 cable terminated to BNC connectors to get the antenna away from my computer because I’ve found that RF and USB do not play well together. I typically try to get the antenna situated in a nearby spot, with a little distance between it and the computer. I bought the Maxpedition Fatty Pocket Organizer Thomas suggested on QRPer.com and a little Amazon Basics Lightweight Mini Tripod.
The AX1, the adapter and tripod all fit in the organizer with room to spare and it fits into a backpack with the radio, battery, cables and my Lenovo Thinkpad 3 laptop. I’m also able to fit in the the Bioenno battery and laptop chargers. At the urging of my XYL, I also have a printed copy of my license in the backpack, too. I haven’t had to show it to anyone yet, but I’m ready, just in case. The backpack is a Mindshift model 18L, designed for photographers, but is easily adapted to contain all of the components I need for a portable activation. Here’s a photo…
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