Tag Archives: Digital Modes

Digital Modes, Field Reports, FT8, News, Portable, POTA, QRP, Travel

Philly: Conrad Activates Independence National Historical Park

5 Comments

Many thanks to Conrad (N2YCH) who shares the following field report:

Activating Independence National Historical Park, Philadelphia, Pennsylvania

August 21, 2024

By: Conrad Trautmann, N2YCH

I recently took an overnight trip from Connecticut to Philadelphia via Amtrak and before I left, I checked to see what parks in Philly I might be able to activate. Conveniently, Independence National Historical Park (US-0738) was a short 15 minute walk from the hotel. So, along with a change of clothes and my toothbrush, my Elecraft KX2 transceiver and AX1 antenna went into the backpack. This is my preferred equipment when I need to travel light.

Equipment List

Independence National Historical Park is actually a series of attractions that are managed and run by the National Park Service, including Independence Hall, the Liberty Bell Center, The Benjamin Franklin Museum and Washington Square. Looking at the map of the location I decided to use a bench in Washington Square to activate from. The yellow highlight in the map below is where I set up.

I was able to set my AX1 up using the tripod on the grass behind the bench, keeping the RF wire and counterpoise out of the path of traffic.

I got all set up, spotted myself on the POTA page and pressed “Enable TX” on WSJT-X and the radio would not transmit. I checked everything…the CIV cable, the audio cables, the settings in WSJT-X, the windows audio settings, the com port…and I still couldn’t transmit. It was decoding fine.

I went to the Elecraft KX groups.io and searched, I searched Google and tried things people suggested and still, no transmit. I changed the CIV cable and the audio cables and interface, since I had spares and even that didn’t work. Thirty minutes later, ready to give up, I tried turning the KX2 off and then back on again and yes, you guessed it, a reboot solved the problem. I’ll try that first next time. I’ve never had that happen before, but you live and learn.

So, I re-spotted myself, got on the air and knocked out 10 contacts pretty fast once I could transmit. I made two additional QSO’s for good measure for a total of 12. Here’s my coverage map…I was running FT8 on 20 meters and I was surprised to make it to Florida to get Matthew, N4MRD. Clint, W9AV also hunted me…that should be a familiar call sign to many activators.

Once I was done and packed up, I took some extra time and checked off a bucket list item. I walked another block North past Independence Hall and visited the Liberty Bell Center to see the historic bell in person. Admission to see the Liberty Bell is free.

Independence Hall
Conrad, N2YCH at the Liberty Bell Center
The Liberty Bell

If you ever head to Philadelphia, this is an easy city site to activate so I recommend bringing your radio to activate the park.

73

Articles, Digital Modes, Guest Posts, How To, Portable, QRP, QRPp

Beyond the Beacon: Conrad Discovers the Unexpected Benefits of WSPR

33 Comments

Many thanks to Conrad (N2YCH) who shares the following field report:

QRPppppp….WSPR

By: Conrad Trautmann (N2YCH)

WSPR, or Weak Signal Propagation Reporter, is a digital mode you can select within WSJT-X. You can use the data that’s generated by the WSPR network to check your own antenna’s performance for transmitting and receiving and also to see what paths are open by band at a particular time of day from your QTH. Recently, I’ve been using WSPR to improve my own antenna systems and to help reduce local noise sources.

Originally developed by Joe Taylor, K1JT, an approximately two minute QRP transmission contains the originating station’s call sign, the maidenhead grid locator and the transmit power level being used. Stations typically use 250mw up to 5watts when they send these signals. WSJT-X allows you to select how often you want to send this transmission and what bands to transmit on. There’s an embedded schedule in WSJT-X that allows “band-hopping” for stations using a multiband antenna to transmit on different bands. When not transmitting, it listens for and decodes other stations transmitting and can post “spots” of those stations to the WSPR network database.

WSJT-X WSPR mode

WSPR Band Hopping Schedule (click to enlarge)

Here on QRPer.com, Thomas, K4SWL posted in this field report what the various flavors of QRP power levels are…

  • QRP: 5 watts to 1 watt (for some contest 10 watts = SSB QRP)
  • QRPp: Less than 1 watt to 100 mw
  • QRPpp: Less than 100mw

Did you know that there are more than 3,000 WSPR HF beacons running on all of the amateur bands all over the world at QRP power or less? Many are running 250mw or less. If you open up WSJT-X and select the WSPR mode, you’ll see that the pull down for power levels give you these options:

  • 37dbm = 5w
  • 33dbm = 2w
  • 30dbm = 1w
  • 27dbm = 500mw
  • 23dbm = 200mw
  • 20dbm = 100mw
  • 17dbm = 50mw
  • 13dbm = 20mw
  • 10dbm = 10mw
  • 7dbm = 5mw
  • 3dbm = 2mw
  • 0dbm = 1mw

You could transmit your own beacon if you choose to using WSJT-X. You can also receive many of the 3,000+ beacons that are on the air right now if you wanted.

Why, you ask?

Let me tell you about the WSPR journey I’ve taken over the past few months and how what I’ve learned has benefitted me, my station and my antennas. Here’s how extreme QRPpp signals can help all of us.

I’m an avid digital operator, and I’ve tested many of the digital modes that WSJT-X, FLDigi, VarAC and others have to offer.

WSPR (Weak Signal Propagation Reporter) is a program embedded as a mode in WSJT-X and you can set it to transmit at the various power levels I listed above and band hop to different bands if your antenna can support those frequencies. When it’s not transmitting, it will receive and post the beacons it hears to the WSPRnet.org web site. For anyone familiar with pskreporter.info, WSPRnet.org is similar in that it provides maps of where and when “spots” are received and the relative signal strength the signals were when received by station, the mode and frequency.

After setting my station to transmit and receive on WSPR and looking at my spots on WSPRnet.org that were reported by receiving stations over the previous day, it was a thrill to see my 250mw signal making it out all over the world. Amazing actually, that such a small amount of power could travel that far. 250mw to Antarctica? That’s pretty good.

I bought a QRP-Labs QCX transceiver and the external companion GPS clock, which supports running WSPR transmission stand alone, without tying up a computer. Then I learned about the Sotabeams WSPRLite Antenna Tester (a 250mw WSPR transmitter) and the various WSPR transmitters offered by ZachTek which can also run without needing a computer.

My goal was to have WSPR beacons transmitting on as many bands as possible. Combining them into a single, multiband antenna posed its own problems, which is a topic for another article. However, all of these solutions just transmitted. I was hoping to also be able to receive and post spots as well.

Then, QRP-Labs (shout out to Hans Summers) came out with the QDX and then the QMX, both of which connect to a PC and are controlled by WSJT-X to do the band hopping transmitting and receiving. Like FT8, WSPR does depend on timing to work best, so using an external GPS clock for the QCX or connecting a QDX or QMX to a computer that can get it’s time from the internet can help keep the transmission cycles in sync with the receiver sites for best reception results.

Various WSPR transmitters and transceivers

This is cool stuff, but still, what’s the point? That’s when a friend I made in the WSPR community, Tom, WA2TP pointed out how to use all of these beacons to improve my station’s receiving capabilities. I have a good HF receiver and a dipole antenna and a hexbeam on a rotor and I figured I was good to go. I was making contacts without any problems. Tom told me this: “It’s all about the noise.”

He recommended using a wideband SDR called a Kiwi that can view the entire HF spectrum from 0 -30MHz on a waterfall at one time. My ICOM IC-7610 can connect to a PC and work with HDSDR software which has a waterfall, but it will only show you the spectrum of the particular band you’re on, not the entire HF spectrum at once. The Kiwi shows the entire spectrum from 0 to 30 MHz and when set up just right, you can see noise in there…a lot of noise, emanating from all sorts of things.

If you’re trying to receive a 250mw WSPR beacon signal transmitting from Australia, the noise from the after-market, wall-wart switching power supply connected to your cell phone charger a few feet away from your antenna could be way noisier and will blank that VK beacon right out. Your antenna and ability to hear distant signals is only as good as how low or quiet the local QRM is that we all have to deal with.

So began my hunt for noise, with a lot of guidance from folks with experience at it. Continue reading Beyond the Beacon: Conrad Discovers the Unexpected Benefits of WSPR →

Digital Modes, Field Reports, FT4, FT8, Guest Posts, How To, News, Portable, POTA, QRP

Karl Heinz’s Pocket-Sized Digital HF Station

18 Comments

Many thanks to Karl (K5KHK) for sharing this guest post, which originally appeared on his blog, Karl Heinz Kremer’s Ramblings:

A Digital Station in Your Pocket

by Karl Heinz (K5KHK)

How small can a complete station to work FT4/8 be? With the QRP-Labs QMX, we have a transceiver that certainly fits the bill for a small station. By itself it can only be used for CW, to use the digital modes, one has to combine it with a computer. Even the smallest laptop is too big the fit into the pockets of my cargo pants – we are trying a pocket sized station after all 😉

In this article, I will describe how to use a QMX transceiver and an iPhone to activate a POTA park with FT8.

The Components

My QMX is the original that was released at FDIM 2023, so it covers 80m to 20m. Mine is serial number #20.

My iPhone is small enough, but unlike Android based phones, the QMX cannot be connected directly to the phone. Apple sells a “camera adapter”, which plugs into the phones Lightning port on one side and provides a USB connection on the other end. $29 for the original Apple part was a bit hard to swallow, so I opted for something cheaper straight from China’s “we clone everything” factories: https://amzn.to/3WDSfUc

[Please note: All Amazon links are affiliate that support QRPer.com.]

 

The picture shows both a USB and a lightning port on the adapter. This should allow the phone to be powered/charged while the adapter is being used – more about that later.

Another limitation is the antenna: The QMX does not have a built-in antenna tuner, and even my QRP sized ZM-2 would have to live in a different pocket 🙂 My plan is to use a resonant antenna so that I would not need a tuner.

The easiest antenna with a good match is a dipole, but that is a bit more challenging to deploy in the field, so I opted for an end-fed halfway (or EFHW) antenna with a 49:1 transformer. I 3D printed a winder that allowed a BNC connector and the transformer to be mounted on the wire winder:

The design came from Thingiverse: https://www.thingiverse.com/thing:2871679

Because I am using a different toroid for the transformer, I had to remove the “bump” that is holding the toroid in place. Going forward, I may change the design a bit more to have so that I can fit more wire on the winder.

For those familiar with the transformers usually used for EFHW antennas, the picture shows two things that are different: As I’ve already mentioned, I am using a different toroid (the Fair-Rite 2661102002 core, which is a type 61), and a different winding pattern. More about that in a future post.

To power my station, I am using a TalentCell rechargeable 12V power bank:  https://amzn.to/3snTyr8

First Test

With everything in place, I tried to make a quick FT8 contact from home with this setup, but with my “big” EFHW antenna in my backyard. Because it was just a quick test, I did not even bother to hook up the charging cable for my phone (more on that later).

The software I am using is iFTx, which supports both FT4 and FT8.

I connected the phone to the adapter from above, connected the adapter via a USB cable to the QMX, and connected the QMX to a 12V power supply (unlike anywhere else in ham radio, 12V here means 12.0V and not the usual 13.8V), and hooked up the antenna to an antenna tuner and then to the EFHW in my back yard.

I answered an FT8 CQ call and successfully completed the FT8 exchange. The software does the automatic sequencing of the different messages, so it is very straight forward to use. With this first contact, I verified that the iPhone/adapter/QMX setup does work.

The Real Test

The next attempt was while camping at Hamlin Beach State Park (US-2068). I set up everything just like at home, but because I was planning on being on the air for a while. I also hooked up the cable to charge my phone while I was operating.

I was able to receive stations, but could not transmit. What made the troubleshooting more complex is that during setup, I created some sparks (that is why I do not like the barrel connector for power). I was pretty sure that the QMX was not involved, but not being able to transmit kind of suggested that I killed the finals. So I put everything away and used my KX2 instead.

Back home, I did some troubleshooting and hooked up a straight key to the QMX and it worked: I was able to finish a few CW QSOS without a problem, so the finals were definitely OK. I then set up the system again for FT8, and sure enough, I was able to make a contact. Because it was a quick test, I did not bother to use the power cable for the phone. By now, most of you probably know what the culprit was, but because I did not spell things out like this, I was still in the dark.

Success At Last

Fast forward a few more days… We went back to Hamlin Beach State Park – but this time to the picnic area – and I set up my station again. And sure enough, once everything was set up, the QMX did not transmit. This is when I took a step back and reviewed everything I had done so far, and slowly I came to the realization that when I provide power through the adapter to the phone, the QMX would not transmit.

I was able to finish my FT8 activation with my pocket sized digital station. I did run into one problem however: iFTx allows to automatically determine one’s grid square – which of course is important for FT8. When I enabled that, it correctly put me into FT13 at first, but a few QSOs later it switched me to JJ00aa – I reported this as a bug to the developer.

Using iFTx with the iPhone

The connection from the phone to the QMX is audio only. iOS does not allow an application to open a serial port connection (unlike Android). This means that the QMX will not receive any frequency information from the phone, and also no PTT signal. For this setup to work, the operator has to make sure that the QMX is tuned to the correct frequency that the correct band is selected in iFTx, and that the QMX is set to VOX mode (this is in the Digi Interface menu).

When configuring iFTx, it is possible to select a “Special Interest Activity” like POTA. This is then added to the CQ call as in “CQ POTA K5KHK FN13”.

As I’ve mentioned before, the application will automatically sequence the correct messages when a station answers the call.
Once the QSO is completed, it will be logged to the iFTx internal log, which can be exported via the usual “send to” methods available in iOS (e.g. email the log, save as a file, …).

When exporting the log, there is a choice of exporting everything, or only the new QSOs since the last export. This will create an ADIF file, which can be submitted to the POTA program, or imported into any other logging program.

At the end, I was successful in building a “pocket sized” digital station based on the QMX, I just need a fully charged phone and cannot depend on charging it while operating.

Click here to check out more articles from Karl on his blog!

Articles, Digital Modes, Guest Posts, How To, News, QRP

Getting Started with HF Digital Modes (Without Breaking the Bank)

23 Comments

Many thanks to Joe (N0LSD) who shares the following guest post:

Getting Started with HF Digital Modes – Without Breaking the Bank

by Joe (N0LSD)

Amateur radio can be an expensive hobby:  the reasons are myriad, made more difficult for newcomers because they tend to not have the experience to know what their requirements might be.  Brick-and-mortar stores where one might bounce ideas off knowledgeable staff, browse the aisles, and walk away with a suitable set-up are pretty few and far between.  Similarly, asking on various internet forums will often be met with, “It depends…” –followed by a wall of text filled with jargon and terminology that can be…intimidating.

For newcomers that maybe don’t have the time to invest in learning CW right off the hop, and perhaps get a bit of mic fright, digital modes such as FT8, JS8, and the like tend to be a great fit.  While “shack-in-a-box” solutions by the big-name manufacturers offer convenience, this convenience comes at a price that can be cost-prohibitive.

What follows is a QRP digital modes kit that I’ve experimented with over the last year.  No single piece of this kit cost more than US$150, and the entire kit can be had for under US$600.  What’s more, nearly everything can be purchased from Amazon.

We’ll start with the most expensive part of this kit:  the radio, which is the Tr(u)SDX.  It can be had on Amazon for US$138, and covers 20m, 30m, 40m, 60m, and 80m bands.  It is a quirky little radio with a sub-par speaker and a tiny little microphone.

The Tr(u)SDX is just about as bare-bones as one can get with an HF transceiver, and is decidedly a compromise.  However, unlike other ultra-compact transceivers, this one will do CW, it will do voice, and it will do *any* digital mode.  It can run on USB power at 1 watt output (micro-USB port on the side of the case); but it can also run on 12v (nominal) power via a 5.5mm x 2.1mm barrel connector on the top of the unit.

I’m powering this radio with a US$43 battery bank (Romoss Sense8P+), and a USB-C to 5.5 x 2.1mm cable (US$8.99) –both available on Amazon.  This battery bank will keep the Tr(u)SDX going for hours –long enough to do multiple POTA activations.  And, because there’s no special adapters, the battery bank can be re-charged in the same manner as a cell phone –or even off a small solar panel.

The sound card interface is the Digirig (US$57) with a US$19.97 cable that is TRRS 3.5mm on one end, and breaks out separate Mic and Speaker 3.5mm TRS.  Now, I will say that a recent firmware revision on the Tr(u)SDX has been demonstrated by the developers of the radio to allow for audio through the micro-USB connector of the radio – so the use of a sound card interface *may* be redundant.  However, in viewing the demonstration video for this, it seems rather dependent upon finding the right micro-USB to USB-A cable; with no clear indication on where one can obtain a cable that meets the specification.  Now, add a USB-C to USB-A or a USB-C to USB-C cable to interface with the computing device, and we’re in business!

So far we have a radio, power, and a way to get sound in and out of the radio.  Now, let’s talk about antennas.  Of course, one can homebrew an antenna for the cost of parts and time in construction and testing.  For the kit I’m using, I went with the N9SAB OCF Dipole –specifically because I do a lot of 80m QRP work.  Also available from N9SAB is a 6m-80m random-wire end-fed for US$89.99 from his eBay store.

If using a non-resonant antenna, an antenna tuner will be needed:  I went with the ATX-100 (US$126 from Amazon).  The reason I went with this is because it recharges with USB-C, which is consistent with everything else in this kit.

For coax, I personally use Times Microwave LMR-240 –a 50-foot length terminated in BNC is US$65 on Amazon.  For something less bulky, perhaps RG-316 from ABR Industries (abrind.com) might fit the bill  The ABR-240 coax at 50-feet in length is US$58.  For a jumper from the tuner to the radio, I use a 3ft RG316 cable from Amazon – which cost me US$13.99.

All that’s left is a device to run software…this can be a Raspberry Pi, or one’s laptop, certainly –however, these are bulky and require special power…and are a pain to re-charge easily.  Another solution is something one might already have:  an Android smartphone.  There are apps (some free, some paid) for RTTY, PSK31/63, WSPR, SSTV – these have been out for some time.  Additionally, one can do many of the modes contained in FLDigi, using the AndFLMsg app (not available on the Play Store –one has to download the .apk file from a 3rd party).  However, what I’ve been using –especially on POTA activations – is FT8CN.  This allows for full-function FT8 using just an Android phone –which can also be charged via USB-C.

[Note: eBay, Amazon and ABR links below are affiliate/partner and support QRPer.com at no cost to you]

Tr(u)SDX $138.00 Amazon
N9SAB Random Wire End-Fed $89.95 N9SAB eBay Store
ATU-100 Antenna Tuner $126.00 Amazon
RG316 Coax Jumper (3ft) $13.99 Amazon
USB-C to 5.5×2.1mm cable $8.99 Amazon
ABR-240 50 ft Coax $58.00 abrind.com
Romoss Sense8P+ Battery Bank $42.99 Amazon
DigiRig MobileSoundcard Interface $49.97 digirig.net/store
uSDX Cable for DigiRig Mobile $19.97 digirig.net/store
Total $547.86

This kit is –for sure– a compromise:  one isn’t going to bust pile-ups or win contests with it  However, for a “starter kit” that can easily be carried in a small backpack that can not only be used for HF digital modes, but also can do SSB voice and CW, it will at least get an operator on the air and enjoying the bands –without breaking the bank.

Accessories, Digital Modes, FT8, News, QRP

BG6LH Designs a Board for Integrated Yaesu FT-817/818 FT8 Operation

10 Comments

Many thanks to Cao (BG6LH) who writes:

Hi, Thomas!

I would like to share my QRP FT8 kit for Field Operation.

A long time ago, I was seeking the most lightweight QRP kits for FT8 field operation. My goal was to have just one radio, one antenna, one phone, without too many cables, boxes, etc.

Finally, I designed a PCB. It is a Bluetooth DIGI Adapter and can be mounted on the rear panel of my FT-818.

Just plug it to the DATA and ACC jacks. It can be powered by ACC jack’s 13.8V Pin.

It works well with FT8CN, an android FT8 app.

Now, my dream has come true!

My Antenna was a so-called GAWANT, designed by JF1QHZ, I guess it’s a simple Vertical EFHW. I built it with a 1.2 meter rod.

It’s working on 7~28MHz bands, not very efficient, but so small and portable.

For FT8 QRP POTA, field operation, all of these components can be put in a small bag, and deployed in minutes.

I shared my PCB design on Github. If anyone wants to modify it, you are welcome to do so!

https://github.com/BG6LH/FT-81x-BT-DIGI-Adaptor

Thank you for sharing this, Cao. This is absolutely amazing and an incredibly clever design! I suspect a lot of FT-818/817 enthusiasts will make this same build via your design!

Thank you for reaching out and for sharing your work with the QRP community! 

Field Reports, FT8, Guest Posts, Mobile, News, QRP

Field Report: Dave ventures into the fog to play FT8 POTA!

5 Comments

Many thanks to Dave (K1SWL) who shares the following field report:

October 6th POTA activation

by Dave (K1SWL)

I’m pretty much a died-in-the-wool CW guy. I’m not averse to dabbling in other modes, though. Friday, October 6, 2023, was such an occasion. I’d noted that there’d been little recent Digital activity in one of our area’s Parks. As if it needs more familiarity, it looms over I-91 only three miles from the Connecticut river. As a result, it’s been activated more than 75 times.

This was Mount Ascutney State Park in VT, and at 3144′, features a paved road to the summit. Off I went!

Finding a parking space at the summit lot wasn’t an issue. The top of the mountain was socked in above 2500 feet. Visibility was 30 to 50 feet, and sightseers were inexplicably scarce.

I normally use a 20M end-fed antenna and homebrew pneumatic launcher. The stunted trees at that elevation made that less practical. I used instead Hustler resonators for 10M and 20M atop the truck cab on a mag mount. I usually consider that setup a compromise, but at 2000 feet above average terrain (HAAT), it didn’t matter.

The operating position inside the truck is quite comfortable. A melamine-clad slab serves as the operating surface. (see above) The chain at the far end was a design ‘iteration’. I’d originally just supported that end on the passenger-side arm rest. I’d operated from the driver’s side, and one day got out, went around and absent-mindedly opened the passenger door. The whole station headed for the ground. I caught the rig but the Vibroplex Iambic paddles were a loss. A fabulous excuse for a Begali- and a hard protective case! When I’m operating from the truck, an IC-706MKIIg and 15-AH Bioenno battery does the honors. If gear needs to be carried any distance, the KX3 makes more sense. The station itself takes two minutes at most to set up.

So how’d it work out? A closeup of the WSJT-X screen (seee above) illustrates it. (The device is an MS Surface.) I was getting as many as 3 replies to my CQs at a time. I wound up ‘interleaving’ three contacts at a time. It got confusing! I need to look into ‘Fox/Hounds’ operation to speed things up for the future.

All in all- a great success. A total of 62 FT8 contacts in a little over 2 hours. 16 of these were on 10M at the start and the balance on 20M. The attached QSO Map (att. 4) shows the contact distribution- mainly eastern US with a few Europeans for good measure. Will I do it again? You bet!

73- K1SWL

Digital Modes, Guest Posts, Kits, News, Portable, QRP, QRP Radios

From idea to kit: Adam introduces the Arduino Digital Modes HF QRP Transceiver (ADX-S) kit

13 Comments

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.

You can refer to Barb’s page on ADX here.

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.

I modified it by cutting two traces on the ADX PCB and it looked ugly, so I redrew the PCB. Continue reading From idea to kit: Adam introduces the Arduino Digital Modes HF QRP Transceiver (ADX-S) kit →

Digital Modes, Field Reports, FT4, FT8, Guest Posts, News, Portable, POTA, QRP, QRP Radios, Reviews

Guest Post: A QRP Labs QDX POTA Field Portable Report

7 Comments

(Photo: QRP Labs)

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.

Articles, News

Using WSPR Data to Study Propagation 40 & 20 Meter Bands

3 Comments

Many thanks to Jim (KX4TD) who writes:

Hi Thomas,

I am a subscriber and ham radio operator circa 1974. Like you (and a lotta hams) I started as a SWL using a transistorized Lafayette Radio receiver.

Last evening, I listened to the April 2022 Wireless Flirt podcast from Ireland where you were interviewed about the comeback of SW radio. Well done Thomas! You are one articulate dude!

I currently have a uBitx that I use for base and portable operation. We share an interest in POTA and other QRP field operations.

My latest obsession is WSPR. Attached [linked below], please find some of my WSPR findings on 40 meters.

73,

Jim KX4TD

Click here to download PDF: “Using WSPR Data to Study Propagation on the 40-meter and 20-meter Bands”

Thank you so much for sharing this and for the kind words, Jim! It’s strange, but I’ve yet to dive into the world of WSPR. I actually have a QRPLabs QCX+ transceiver kit I purchased specifically to explore WSPR. I just need to find the time to build it now! 

Thanks again for sharing your amazing report!

How To, Morse Code, News, Portable, POTA, SOTA

How to use the Reverse Beacon Network (RBN) for automatic POTA and SOTA spotting

39 Comments

If you’ve read my field reports or watched any of my activation videos, you’ve no doubt noticed that I rely very heavily on automatic spotting  via the Reverse Beacon Network (RBN) for both POTA (Parks On The Air) and SOTA (Summits On The Air).

I’ve gotten a lot of questions about how to use the RBN functionality for both SOTA and POTA, so thought I might clarify (in very basic terms) how the system works and how you can take advantage of it.

Note: CW and Digital Modes Only

Keep in mind that Reverse Beacon Network spotting only works with CW and some digital modes.

I, personally, have only used it for CW activations.

The system does not currently recognize voice transmissions (although as voice recognition becomes more accessible and effective, I wouldn’t be terribly surprised if something like this is offered in the near future!).

Here’s how the RBN works

The RBN is essentially fueled  by a global network of volunteer receiving and decoding stations that feed information into the RBN spotting system. This system is running 24/7 and recording spots constantly.

This is what the RBN spots search results look like using my call at time of posting.

If I hopped on the air right now and made at least two generic CQ calls with my callsign–barring any abnormal propagation–the RBN would no doubt collect my information and spot me automatically to their network.

Click here, for example, to see all of the times the RBN has spotted me recently. Click here to search for your own callsign on the RBN.

To my knowledge, the RBN is a completely independent resource and not directly affiliated with POTA, SOTA, WWFF, or any other contest or activity. Continue reading How to use the Reverse Beacon Network (RBN) for automatic POTA and SOTA spotting →