Category Archives: QRP

Taking the Xiegu G90 QRP transceiver to the field!

Earlier this week, I took delivery of a new Xiegu G90 general coverage QRP transceiver. I’m reviewing this portable rig for The Spectrum Monitor magazine. Although this Chinese manufacturer has been around for a few years, this was my first purchase of a Xiegu product.

I’ve had the G90 on the air from home for a couple days, but I feel like the best way to test a QRP transceiver is in the field!

Due to the Covid-19 lock-down and a number of our regional parks either being closed or severely limiting visitors, I haven’t made many POTA (Parks On The Air) activations this year.

Recently, however, North Carolina has been opening state parks and allowing visitor access to hiking trails and picnic areas, but keeping all facilities (stores, cafes, visitor centers, and restrooms) closed to the public.

Yesterday, our family decided to pack a picnic lunch and head to Mt. Mitchell State Park (POTA site K-2747). My wife knew I was chomping at the bit to play radio in the field and actually made the suggestion. (She’s a keeper!) 🙂

There were only a dozen people at the park so we essentially had the place to ourselves. Better yet, it gave me the opportunity to pick out the most ideal picnic site to set up and deploy my EFT Trail-Friendly 40/20/10 antenna.

The G90’s backlit color display was actually quite easy to read in the field. My phone’s camera filter made it look darker than it actually was.

My POTA activation was unannounced and I didn’t have Internet access to self-spot on the POTA website, so I started the activation old school by calling “CQ POTA” until someone happened upon 7286 kHz.

After perhaps 10 minutes of calling CQ, Greg (KE0HTG)–a helpful POTA chaser–finally found me and spotted me on the network.

I worked a few stations in succession, but summer QRN levels were incredibly high and I believed static crashes were cloaking would-be contacts. The G90 has no RF Gain [Actually, thanks to this feedback, I now know the G90 does indeed have an RF Gain control (firmware version 1.73 and higher).] I asked one kind operator if he would hold while I switched over to my trusty Elecraft KX2.

The KX2 did a much better job managing the noise and that same op was easily readable where with the G90 I could barely copy him. I suspect I could have tinkered with the G90’s AGC levels to better mitigate the noise, but I didn’t want to do this in the middle of an activation.

I worked about fifteen stations with the Elecraft KX2 on 40 meters.

One real advantage of the KX2 during a POTA activation on SSB is its voice memory keyer (of course, it also has a CW memory keyer). I simply record my CQ and have the KX2 repeat it until someone replies, then I hit the PTT to stop the recording. Not only does this save my voice, but it also gives me an opportunity to eat my lunch while calling CQ!

I eventually moved up to the 20 meter band and switched back to the Xiegu G90.

On the 20 meter band, the G90 handled conditions like a champ.

Someone eventually spotted me on 20 and I worked a few stations.

The 20 meter band was very fickle and unstable yesterday. For example, I struggled to finish a contact with an operator in Massachusetts, yet got a solid 59 report from Spain with only 20 watts.

No activation is complete without brewing a cup of coffee on the alcohol burner!

I had a great time with the G90 in the field. I can see why it’s become such a popular transceiver as it offers incredible bang-for-buck (it can be purchased new as low as $450 US shipped).

This week, the noise levels on the 40 meter band should be very high here in North America, so I plan to spend more time with the G90 settings and see if I can mitigate the QRN a little better. I’d welcome any tips from G90 owners.

And yes, I’m already eyeing a couple of parks to activate next week!

Post Readers: Please comment if you’re familiar with the Xiegu G90 or any of the other Xiegu transceivers.


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Interview on the ICQ Podcast

I’m honored to have been interviewed by Frank Howell (K4FMH) for the ICQ Amateur / Ham Radio Podcast. The interview was posted as a podcast this weekend.

If you’re not familiar, the ICQ podcast is posted every fortnight and runs about 1.5-2.5 hours or so depending on news items and features. Here’s the description of this episode (#322):

In this episode, Martin M1MRB is joined by Chris Howard M0TCH, Martin Rothwell M0SGL, Ed Durrant DD5LP, Frank Howell K4FMH and Bill Barns N3JIX to discuss the latest Amateur / Ham Radio news. Colin M6BOY rounds up the news in brief and this episode’s feature is – Passion of Shortwave Listening with Thomas Witherspoon K4SWL.

The show can be streamed via the ICQ podcast YouTube channel or on their website.

The ICQ Podcast website also links to the many ways you can subscribe and listen to their shows published every two weeks.

Many thanks to Frank for inviting me to be interviewed–I really enjoyed talking shortwave with a fellow shortwave radio enthusiast (and long-time SWLing Post reader!).

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ALT-512 QRP transceiver review in RadCom

If you’re a member of the Radio Society of Great Britain (RSGB) you may have seen my review of the ALT-512 QRP transceiver in the March 2020 issue of Radcom. This was my first review for Radcom after having been invited to submit a review at the 2018 Hamvention.

I love Radcom so was pretty chuffed to see my review in the March pages:

I had the ALT-512 here at SWLing Post HQ, on loan from the manufacturer, for the better part of six months. I got to know this little radio inside-out. I’ve operated it in the field, in the shack and covered ever mode including FT-8 contacts during portable operations and even in a high school classroom.

Operating FT-8 with my ham radio class high school students last year. The ALT-512 is a digi-mode champ. With a very modest indoor mag loop antenna we averaged about 110 miles per watt.

The ALT-512 is a versatile, sturdy little rig–designed and manufactured in Bulgaria. I really only had minor complaints about this transceiver. I saw a bright future for this little rig. It was well-designed and backed by a company and team of ham radio operators that had already successfully launched several other transceivers.

Then the unexpected happened…

Early last month, I learned that the ALT-512’s main engineer and designer, Dobri Hristov (LZ2TU), passed away.

If you own the Sky SDR or LD-11, you may have communicated with Dobri at some point when you needed technical support.  Dobri was a well-respected fellow and distinguished ham radio operator/DXer. I corresponded with him quite a few times in the past.

Sadly, when Dobri passed away, he took the ALT-512 with him.

Here’s the announcement from Aerial-51’s website.

I think the ALT-512 would have been very successful and competitive in the European market and beyond.

Dobri passed away as the March 2020 issue of Radcom was being printed. He never got to see it, but I’d like to think he would have been quite proud of his little transceiver. In the end, I think it was an overall positive review.

You can judge for yourself: Aerial-51 recently published a copy of the ALT-512 review with permission from the RSGB.

Radcom

If you’re into ham radio and are looking for a top-shelf publication, consider joining the RSGB and subscribing to Radcom. I highly recommend them even though their judgement was obviously impaired when they invited me to write a review–! 🙂

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The uBITX V6, winter weather and power outages

Yesterday, a weather front moved through the area that dropped temperatures from an unseasonably high of 50F to 25F in the space of a couple of hours.  Fronts like this always equate to high winds here at our altitude. This time, it packed a little snow as well.

Last night, around 22:00 local, our power went out due to a fallen tree further down the road.

Here at SWLing Post HQ, we don’t panic about power outages. As I’ve mentioned before, our refrigerator, freezer and some of our home lighting is solar-powered and off-grid–we also rely on passive solar heating and a good wood stove to keep us warm and cozy.

Without fail, I always use power outages as an excuse to play radio on battery power.

This morning, the uBITX V6 transceiver was already hooked up to a LiFePo battery on my desktop, so I simply turned it on and started tuning around the 40 meter band, where I had recently logged a few POTA contacts. Problem was, the band was absolutely dead, save a couple weak stations. After thinking about it a few seconds (keep in mind this was pre-coffee) I put on my boots and coat, walked outside and confirmed my suspicions: the antenna feedline had become detached from my external ATU box.

The winds were strong enough last night, that the ladder line pulled itself out of the banana connector jacks on the side of the ATU box. This happens quite often during periods of high winds and is a bit annoying. Of course, I could secure the feedline in such a way that it would easily survive high winds without disconnecting, but frankly this is an intentional design choice. You see, when a black bear walks into my feedline, it easily disconnects before the bear gets tangled, up, frustrated and yanks my antenna out of the tree!

Trust me on this: bears and antennas don’t mix. I speak from experience.

After re-connecting the antenna, I fired up my portable alcohol stove (the one you might have seen in this post), boiled water, and made a fresh cup of coffee to take back to the shack.

I turned on the uBITX once again and found that the 40 meter band was chock-full of strong signals.

It’s time to go chase a few more parks today and plot my next POTA activation.

Frankly, I’m in no hurry for the power to be restored.  It’s a wonderful excuse to play radio.

Readers: Anyone else enjoy radio time when the grid goes down? Please comment!


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Assembling the uBITX V6 QRP transceiver

Last Friday, after returning from holiday travel, I found a belated Christmas gift on my doorstep: the new uBITX V6 QRP transceiver.

In the spirit of full disclosure, this package wasn’t delivered by Santa, rather by DHL in record time from India. As I mentioned in a previous post, I simply couldn’t resist purchasing such an affordable general coverage transceiver.

To be clear, the uBITX V6 isn’t really a kit. The boards are all fully populated by a women’s cooperative in India. You can purchase the uBITX V6 for $149 without a chassis and for $199 with a custom metal chassis. I purchased the latter.

Assembly may take thirty to forty minutes following HF Signals’ online guide. I employed my twelve year old daughters who pretty much assembled the entire radio–I only helped seat the display to the main board.

There is no firmware or software to upload. Simply assemble the radio, solder a power cord to the supplied coaxial plug (hint: positive tip polarity), connect an antenna, connect a power supply, and turn it on.

You’re on the air!

So far, I’ve only scanned the bands and listened to QSOs and broadcasters (no AM mode, so I’ve been zero-beating stations in SSB). Today, I hope to chase a few parks via the Parks On The Air program.

I still need to calibrate the radio yet (although it does zero beat WWV perfectly).

If you purchase the uBITX V6, don’t expect a benchmark transceiver. This uBITX V6 feels more like a work-in-progress and I assume the pre-loaded firmware is simply a first iteration.

Since the radio is open source, I expect hams will soon hack this rig to go above and beyond its basic (understatement alert–!) feature set.

If you’re a CW operator, you might hold off on purchasing until someone has properly implemented the mode. I made some test CW CQs into a dummy load just to check out the keyer and I honestly don’t think I could manage a proper QSO at this point. Sending is sluggish and…well…awkward.

Note that I will be writing a full review of the uBITX V6 for a future issue of Radcom (the RSGB’s monthly publication). Check back here for uBITX V6 notes along the way.

Also check out the excellent blog of our friend, John Harper (AE5X), who has also recently put the uBITX V6 on the air!

Anyone else order a uBITX V6? Please comment!


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Mario acquires an Index Labs QRP++ general coverage transceiver

May 1996 QRP Plus ad from QST (Source: WD8RIF)

Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who shares the following guest post that was originally published on the Delaware Valley Radio Association (DVRA) website:


Amateur Radios from the Past: The Index Labs QRP++

The Index Labs QRP ++ was an intriguing little radio manufactured back in the mid-‘90’s by Index Labs of Gig Harbor, WA.  For those interested in QRP (low power operating, generally less than five watts output) this transceiver filled the bill perfectly.  It supports CW and SSB, transmits on all WARC bands, covers 1.8 – 30 MHz receive, has full break-in CW and a built-in iambic keyer.  It boasts 20 memories, weighs four pounds (perfect for portable operation) and measures 5.5 x 4 x 6 inches.  It’ll run on a 12V 1.5 amp supply or a stout 12 volt gel cell.  The internals (see second pic) are an engineering masterpiece with stacked circuit boards reminiscent of commercial rigs.

Index Labs QRP ++ on the test bench

I recently acquired one of these radios as I was heavily into QRP in the 1970’s while using a TenTec Argonaut 509 and vertical on our apartment house’s roof.  Back then the sunspot numbers scored much higher than today and many contacts were made, most notably a CW contact with Japan with a paltry one watt.  So for nostalgic reasons I had to have one of these QRP++ rigs even though more modern and sophisticated versions are available.

At the moment bench tested is being done prior to sending it into action.  One important component needing replacement was the memory battery which was totally kaput.  Interestingly, this battery not only keeps the 20 memories alive but also brought back to life the CB radio-style S-meter reminiscent of radios from decades ago. Other items on the testing  “to do” list will be checking power output, frequency accuracy, drift, and finally, on-air performance.  The radio will feed a ground mounted 31’ vertical with 53 radials. With the right ionospheric conditions hopefully contacts will be aplenty.

Neatly stacked circuit boards and clean layout of QRP++

Unfortunately, no service manual exists for this gem, but it rates a 4.1 out of 5 on the eham.net Richter scale, and a number of ops have published helpful information on problems, solutions and modifications.  Notably the first run of these radios was later replaced with improved models boasting higher performance via a custom designed mixer, so knowing the serial number of your unit helps to determine if yours was an upgrade.

Rear panel control layout. Power is adjustable and tested at a hair under 5W.

You can read and see more photos from the author, Mario Filippi N2HUN, at https://www.qrz.com/lookup/n2hun

Click here to read this article on the DVRA website.


Thank you, Mario, for sharing this article and many thanks to the DVRA for allowing us to re-post it.

I owned a QRP++ for a few years and absolutely loved it. At the time, it was one of the most portable full-featured transceivers on the market. Although it can struggle in RF dense environments like Field Day or other contests, for daily use it was very effective. I eventually sold mine to fund the purchase of the Elecraft KX1 and, later, KX3.

I always loved the simple front-panel ergonomics of the QRP+ and QRP++. It’s an incredibly easy rig to operate in the field. Plus…it has a bit of a “cute” factor, if you like radios shaped like cubes.

There is a dedicated email discussion group for Index Labs transceivers–currently, they’re on Yahoo Groups but may migrate to another platform by end of year.

In addition, SWLing Post contributor, Eric McFadden (WD8RIF), has an archived webpage with a wealth of information about the Index Labs QRP+ series.

Thanks again for sharing this, Mario! I know you’ll enjoy the QRP++ once you get it on the air!


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Final review of the CommRadio CTX-10 QRP general coverage transceiver

Earlier this year I published what I called an “initial” review of the CommRadio CTX-10 QRP transceiver, promising an eventual final review. The reason for this is that I sensed there were important CTX-10 updates on the horizon, and I wanted to re-evaluate the rig once the upgrades had been implemented through firmware.

This final review builds upon the initial review––think of it as the  second installment, or “Part 2″––so if you’re considering the purchase of a CTX-10 and haven’t read the previous post about it, please do read the initial review first.

Upgrades

As anticipated, via simple at-home firmware updates, since my initial review the CTX-10 has now been upgraded and tweaked a number of times. [Click here to view all of the documented firmware updates and notes at CommRadio.]

I’ve been very pleased with the attention CommRadio has paid to their customer feedback on some of the most important requests.

Instead of reiterating what I wrote in the initial review, I’ll jump straight into the upgrades.

Operating split

At time of posting my initial review, the CTX-10 didn’t have A/B VFOs. This was my primary gripe about the CTX-10, because without A/B VFOs, there was no way to operate split, which meant that you could not work DX stations that use split to manage large pileups. This is actually a really important feature for a QRP radio because during split operation, a pileup is pulled apart across a few kHz of bandwidth, thus giving a 10-watt signal a better chance of being heard through a collection of legal-limit signals.

On June 10, 2019, CommRadio released a firmware package that added A/B VFOs and the ability to operate split to the CTX-10.

Even though there are only a limited number of buttons on the front panel, it’s incredibly simple to enter into split mode:

  1. Chose the frequency and mode;
  2. Hold the STEP button for one second or more, then release. You’ll then see a split display indicating the TX and RX frequencies.
  3. Use the left arrow key [<] to toggle between them.

I do like the clear TX and RX lines, which leave no doubt in the user’s mind what the frequency used for transmitting and receiving is. On some radios, this can be a bit confusing.

Split operation is simple and effective, thus I consider this issue fully resolved.

ATU flexibility

In my initial review, I noted that the CTX-10 ATU needed near-resonant antennas for the ATU to make a strong 1:1 match. Indeed, a number of times I actually used a near-resonant antenna in the field––the EFT Trail-Friendly, for example––and the ATU couldn’t get below a 3:1 match. For what it’s worth, CommRadio states that the CTX-10 can easily handle 3:1.

Making a Parks On The Air activation at Tar Hollow in Ohio.

CommRadio has made modifications to the ATU function, improving the performance of the antenna-tuner algorithm, which had a significant impact on 80 and 60 meters. I’ve also had better luck with a number of field antennas I’ve tried on 40 and 20 meters. Is it as good as the Elecraft KX-series ATUs? No, but I consider those ATUs to be some of the most flexible on the market.

Having a built-in ATU on the CTX-10 is certainly a valuable feature in the field. When I need to match a challenging antenna with the CTX-10, I bring my Emtech ZM-2 manual tuner along for the ride. A perfect combo.

SSB operation?

There still is no way to adjust the microphone gain control nor microphone compression on the CTX-10. Much like a military or commercial radio, the CTX-10 is optimized for just one style of mic: in its case, the modular MFJ-290MY or Yaesu MH-31A8J handheld mic.

The CTX-10 microphone input has a limiting pre-amplifier with built-in compressor and ambient noise gate–in short, the CTX-10 handles all microphone settings automatically.

Through firmware updates, a number of positive adjustments have been made to the microphone settings:

  • the microphone-decay timer has been tweaked so that audio clipping is less of a concern
  • audio clarity and gain have been improved
  • audio power has been improved resulting in .5 to .75 watts of additional peak power
  • microphone audio leveling has been improved
  • VOX attack and decay timing has been improved

These are all welcome adjustments.

I would note here, though, that if you plan to use a mic other than the MFJ-290MY or Yaesu MH-31A8J handheld mics, you will have a limited means of adjusting the mic parameters unless you have an external mic EQ. A number of readers, for example, have asked about using their Heil boom headset with the AD-1-YM cable adapter on the CTX-10. Boom headsets are a wonderful tool for field operation because they free your hands to log contacts. As for using boom headsets on the CTX-10, since I don’t have the appropriate adapter, I can’t speak to this. But since you can’t control mic gain, it might take time to learn how to position the boom mic and adjust your voice level for optimum performance.

CW operation

As mentioned in our initial review, the CTX-10 does not support QSK/full break-in operation. Rather, the CTX-10 uses a traditional relay for switching between transmit and receive.  During CW operations, you’ll hear a faint relay click when switching from TX to RX and back again.

This isn’t a problem for me, as I rarely set my CW rigs for full break-in, but the CW hang time delay on the CTX-10 is not currently adjustable. For high-speed CW ops that prefer a faster relay recovery, I suspect this could be an annoyance.

There have been recent CTX-10 firmware upgrades that have helped solve issues found with CW keyer timing in early units. I found the timing issues were mainly present while sending high-speed CW (25 WPM+). My buddy Vlado (N3CZ) put the CTX-10 through some high speed tests, and was pleased with the results overall.

I will reiterate here that the CTX-10 lacks other controls many CW operators appreciate. Currently, the CTX-10 lacks a sidetone control; as a result, you cannot change the sidetone volume/tone, nor can you turn it off. I continue to hope that CommRadio will fix this quirk via a future firmware upgrade.

The CTX-10’s built-in CW keyer does not currently support iambic keying. Meaning, when both levers of a dual paddle are closed simultaneously (squeezed), it will not send a series of alternating dots and dashes. I imagine this could be addressed in a future firmware update.

Additionally, without re-wiring your paddle, you can’t change which side of your paddle sends ‘dits’ and which sends ‘dahs.’  A minor con, for sure–still, most modern QRP transceivers allow you this flexibility.

All in all, the CTX-10 will serve the CW operator much like a military set in field operations. True, I wish it had a few more adjustments, but it has all of the basics, and I’ve received several great reports regarding signal and tone.

Revisiting the basic feature set

Let’s be clear: as I stated at length in my initial review, the CommRadio CTX-10 was designed around simple operation, like one might expect from a military or commercial channelized radio. I know ham radio operators and preparedness enthusiasts who prefer this approach to gear design, and they will appreciate this CTX-10 design philosophy.

Still, the CTX-10 lacks many of the features and adjustments you’d typically find on a QRP transceiver in its price class. Instead, the CTX-10 was designed to handle many of these adjustments automatically.

The CTX-10 still has no separate RF gain control. The CTX-10’s RF gain is directly tied to the three AGC settings (slow, medium, and fast). While I believe it does a fine job of adjusting RF gain, I do ride an RF gain control a lot during noisy summer conditions, and miss this feature.

The CTX-10 still has no passband (PBT) control, notch filter, or noise blanker––all features I’d normally expect in a QRP radio at this price level.

There are no CW (os SSB) memory keyers. I wouldn’t expect these, as I believe only the Elecraft KX2 and KX3 sport this feature in this price class of QRP radios.

Please note: some of these features could potentially be added in future firmware upgrades. If one of these items is keeping you from purchasing the CTX-10, please contact CommRadio and inquire.

Is the CTX-10 for you?

The CTX-10 on air at the W4DXCC conference

With the most recent upgrades, CommRadio has solved the major issues that kept me from heartily recommending it in my initial review.

The addition of split operation was especially key for me, as I do operate split. The more nuanced adjustments to the CW keyer, an extra feature to prevent the radio from accidentally turning on while in transit, and the adjustments to the mic algorithm, all make this radio more pleasant to operate at home or (especially) in the field.

As I mentioned in the initial review, the CTX-10 owner is one who values a very simple, straightforward radio. Perhaps someone who began operating in a commercial, military, or aviation field, and/or who likes the “get on and get the job done” approach.  Someone more interested in making contacts than in radio operations and refinements. Those who want a sturdy, lasting, no-frills, set-it-and-forget-it rig. If that’s you, take a closer look at the CTX-10: it may just suit your needs to a T.

If, however, you’re looking for a full-featured QRP radio with many of the features and nuanced adjustments you’d expect in the shack, check out the Yaesu FT-818, Elecraft KX2, or Elecraft KX3. All of these excellent rigs are time-tested and very flexible.

The two major advantages of the CTX-10 over competitors are:

  • the ability to charge the internal batteries from almost any voltage source, and
  • a higher TX duty cycle (without needing to add external heat sinks).

I believe the CTX-10 will have strong appeal for radio enthusiasts who value these characteristics:

  • All-in-one-box portability with no extra wired accessory components
  • Best-in-class internal battery life
  • Best-in-class intelligent battery charging
  • HF packs
  • Digital modes like FT-8 and the ability to operate them in the field from internal batteries for extended periods of time
  • The equivalent of a simple portable military/commercial set
  • A well-balanced receiver with few manual adjustments
  • Broadcast listening, as the CTX-10 is also superb broadcast receiver
  • Best-in-class hardware

The CTX-10’s overall construction and components are, as I’ve said, near mil-spec. While the CTX-10 isn’t weatherized or waterproof––no more than any of its current competitors––the construction is top-shelf, for sure. It should run for decades without need of repair.

The CTX-10 is built like a tank, and has excellent receiver characteristics for field operation. It’s also designed and manufactured right here in the USA. All the better.

Click here to check out the CTX-10 at CommRadio.

Click here to check price and availability at Universal Radio.


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