A review of Ten-Tec’s Argonaut VI QRP transceiver, Model 539

The Ten-Tec Model 539, A.K.A. Argonaut VI

The Ten-Tec Model 539, A.K.A. Argonaut VI

And now, what we’ve all been waiting for:  the Ten-Tec Argonaut VI has finally hit the market.   Manufacturer Ten-Tec has already begun shipping the new units–I hear they’ve already sold out the first production run.  For the past two months, I have had the pleasure of beta-testing this newest QRP transceiver, and I’m ready to share my findings.  [Do please note that, other than beta-testing, I have no relationship with Ten-Tec.]

I authored a post about the Model 539 when Ten-Tec first disclosed it at their 2011 Hamfest. The reactions and questions from readers came flooding in–so many, in fact, that I invited readers to send in those questions to share with the engineers at Ten-Tec.  I presented these to the company, and posted Ten-Tec’s helpful responses.

Prototype of the Ten-Tec Model 539 QRP transceiver

Prototype of the Ten-Tec Model 539 QRP transceiver from the 2011 Ten-Tec Hamfest. Note that the speaker no longer has an externally mounted grill.

In truth, I don’t think that Ten-Tec was quite prepared for all of the interest in their modest QRP transceiver. But it was no surprise to me: I’ve always been a fan of Ten-Tec, and although I’ve not been as excited by the QRP offerings since the early Argonauts, I knew I wasn’t alone in my appreciation of this US-based radio company’s quality products.

The following review is not a test-bench review–it is, rather, a consideration of the usability, ergonomics, design, basic performance and, well, fun factor of the new Argonaut VI.  It’s only fair to note that I don’t review transceivers often; rather, I focus primarily on receiver reviews at my alternate radio blog.  But I could not resist the opportunity to investigate the newest in this venerable line of transceivers.

Size-wise, the Argonaut VI is smaller than the Elecraft K2 in every dimension.

Size-wise, the Argonaut VI is smaller than the Elecraft K2 in every dimension.

You will note that I compare the Argonaut VI to the Elecraft K2 a number of times. Why? In my opinion, the K2 is the Argonaut VI’s closest competitor. It, too, is a front-panel QRP transceiver not for general coverage. While there are a number of differences, of course, I nonetheless feel the K2 is a closer match than the new Elecraft KX3, the Yaesu FT-817, or the Icom IC-703. Plus, I have a K2 that I already know and love here in my shack, so by default it has been my point of comparison throughout the beta-testing period.

Argonaut VI: first impressions

The Argonaut VI is an attractive, simple, sturdy little radio. It reminds me a great deal of the Ten-Tec Scout outfitted with its simple front panel. The front features two knobs: one controls the AF gain, while its outer ring controls RF gain; the other controls the bandwidth, while its outer ring controls the pass band. There is also an appropriately-sized display panel, quality tuning knob (see below), four multi-function buttons, and a three-position toggle switch.

The TMB switch is a simple and effective way of giving the Argo VI's four function buttons multiple assignments.

The TMB switch is a simple and effective way of giving the Argo VI’s four function buttons multiple assignments.

A toggle switch? I can’t think of a recent front-panel radio in production that has had a proper mechanical toggle switch. On the Argo VI, this makes for a simple method to give the four function buttons a total of three one-push functions, each, for a total of twelve functions. Ten-Tec refers to this switch as the “TMB” (i.e., “Top-Middle-Bottom”) switch.

Size-wise, the Argonaut VI is smaller in every dimension than the K2 (see photos). Its physical dimensions are 2.25″H x 6.5″W x 7.6″D, less the knobs and connectors. It weighs a mere 3.6 lbs, and feels very light in my hands. The Argo VI has a sturdy Ten-Tec bail that snaps into the perfect position for tabletop operations. The display is crisp and clear, and actually contains a lot of information:

The Argonaut VI display is compact, yet crisp, clear and displays all important information.

The Argonaut VI display is compact, yet crisp, clear and displays all important information.

  • Frequency
  • 2nd VFO frequency
  • Mode
  • AGC speed
  • S Meter/SWR
  • Output power
  • Pre-amp

The display can be switched (via an internal setting) to blue (default), green, or red. One nice touch: the dot in the Ten-Tec logo is actually a red LED that lights up on transmit and ALC peaks.

Tuning knob

This is the best tuning knob I've ever used on a QRP rig

This is the best tuning knob I’ve ever used on a QRP rig

Perhaps I place more emphasis on a tuning knob that other hams. I liken it to shutting the door on a quality car: you want the door to shut solidly and feel substantial. But it may be more like a car’s steering wheel–after all, the tuning knob is how one interacts with the radio. To me, the tuning knob is often a measure of a radio’s overall quality, in my humble opinion.  As for the Argonaut VI?  Here’s the answer:  I was so impressed with the tuning knob on the Argonaut VI that I actually confirmed with Ten-Tec that the beta-unit’s tuning knob would also be used on production models. In short, the Argo VI’s tuning knob is heavy, perfectly-sized, has a light tactile grip, and is silky-smooth to operate. There is no play whatsoever in the action. I like the adaptive tuning, too–when you tune slowly, you’re changing the frequency by hundredths of a kHz; spin the knob quickly and you’ve just shot across the band. After tuning the Argo VI for a bit, other small radios’ tuning knobs begin to feel cheap.


When I first played with the Argo VI at the Ten-Tec hamfest, I was impressed with the simplicity of the front panel. This is an important factor because I simply won’t use a radio that isn’t pleasant to use/control, and I find that too many front buttons and general visual fussiness can be a distraction. To illustrate my point, when the Yaesu FT-817 hit the market over a decade ago, I was among the first to purchase one. I liked the idea of a small transceiver that I could tuck in my carry-on and take with me as I traveled. But I ended up selling the FT-817, however, because I hated the ergonomics and multi-function buttons. Button spacing was too tight for my larger hands, important multi-functions seemed to overlap, and menus were buried too deep for convenient operation. The FT-817 had a profound impact on all other buying decisions I’ve made since, and taught me that too much can simply be…too much.

The red dot in the Ten-Tec logo is actually a red LED that lights up on ALC peaks and CW transmit. (Click to enlarge)

The red dot in the Ten-Tec logo is actually a red LED that lights up on ALC peaks and CW transmit. (Click to enlarge)

Happily, on the Argo VI the most often used transceiver functions have dedicated buttons/knobs, and the display includes everything I need. Clean, clear, straightforward–this rig provides a pleasant operating experience.

For basic operations like rag-chewing, scanning the band, switching modes, switching bands, adjusting RF/AF/BW and PBT, you’ll be pleased, too.  None of these operations require calling multi-functions or toggling the TMB switch (assuming you’re already in the “M” position).

But after spending some time on the air, I realized that there is a bit of a learning curve you’ll have to overcome before front-panel operations become entirely fluid and intuitive. To change RIT, you need to toggle the TMB switch to “B”, then press the RIT (BAN) button to toggle RIT on and off. If you hear DX working split, you’ll need to move the TMB switch to the “T” position, then set the A/B and SPL buttons; if you need to change modes or turn on the pre-amp, then you’ll have to move TMB back to “M.”

In the first few hours of  testing the Argo VI, I found it easy to forget that I had the TMB switch set to a certain position when pressing a multi-function button, thus I was sometimes not receiving the response I expected. Several times I intended to change the band, but had the TMB set to “T” and resultingly opened the output power setting, or pressed the MOD button only to find that TMB was set to “T” as I toggled A/B VFOs.

Click to enlarge

Click to enlarge

While this was distracting at first, I soon became accustomed to changing the setting, then moving the TMB back to the “M” setting afterward. Now I find I very rarely make a mistake.

On the Argo VI, all of the buttons and knobs are adequately spaced. You could operate this rig outside with lightweight insulated gloves on, should the need arise.

All in all, the ergonomics are excellent on the Argonaut VI.


Before I begin talking about this little transceiver’s performance, I want to point out its two most obvious shortcomings:

  • The Argonaut VI lacks 12 and 60 meters (ouch!)
  • There is no internal ATU (auto antenna tuner), nor is there an option for one

If those two negatives are deal-breakers for you, I could certainly understand. You might want to consider a basic KX3 with ATU ($1070 unassembled, $1170 assembled) or a K2/10 with ATU ($1280 unassembled), instead.


The Argo VI has a relatively small footprint on my radio shelf.

But if, like me, you use neither 12 nor 60 meters very often, you may not miss them.  Admittedly, the lack of 12 meters is unfortunate because it’s such an ideal band–when conditions are right–for easy QRP field operation. However, I am very pleased the Argo VI has 160 meters.

An internal ATU–or the option to have one installed later–is certainly a negative for those of us who like a simple Field Day radio set-up. From my point of view, other than my Elecraft KX1, I’ve never had a radio with an internal ATU; I have two portable tuners (the LDG Z11 Pro and Elecraft T1) that work wonders. The way my shack is designed, I have a remote auto-tuner outside at the feed point of my antennas and thus have no tuner in my shack–so if I had an internal ATU, I’d have to turn it off 95% of the time. If your shack is set up similarly, you might not mind not having an ATU.

If you’re concerned about the performance of the Argonaut VI, let me assure you now: you will not be disappointed. Indeed, the receiver in the Argonaut VI must be one of the best I’ve ever heard in any radioespecially in this price class ($1000).  It is truly remarkable.  I’m eager to learn how Rob Sherwood rates the Argonaut VI, but I suspect it will rank among the top few.


Click to enlarge

What is most impressive in the Argo VI is its incredibly effective variable DSP filtering. I experimented with the variable bandwidth and pass band during crowded CW conditions, and found that each and every time I could zero in on one QSO and block everything else. It’s also highly effective when used with SSB. Based on the reviews I’ve read of the Eagle, this is obviously derived from its DSP architecture and has similar performance characteristics. [Future Argo VI owners, I eagerly welcome A/B comparisons of the Eagle and Argo VI--please comment!]

IMG_6494You’ll be happy with both the Argo’s sensitivity and its ability to reject adjacent signals. Compared with my Elecraft K2/10, the Argo VI’s sensitivity had an edge in every band I tested, and to my ear, the noise floor is lower on the Argo VI as well.  Most noticeably, however, is the Argonaut’s audio fidelity, which is far superior to that of the K2. Whether using headphones or using the built-in top mounted speaker, you will be pleased. The speaker delivers an impressive sound for its size. I tend to hook up external speakers to my smaller transceivers, but in this case I never felt I needed to. With headphones, the audio is even more impressive. I do wish the headphone jack was on the front panel instead of the back, though.

Though I haven’t spent enough time with the KX3 to compare audio fidelity, I imagine the KX3 and Argonaut VI would be a fair contest.

I can say that audio fidelity is the primary reason I continue to turn to Ten-Tec for transceivers and receivers. In my opinion, like Kenwood, Ten-Tec invests more resources into insuring superb audio fidelity–even at the cost (in this case) of uber-low current drain numbers (although the 550 mA drain on receive must be the lowest Ten-Tec has ever produced in a digital transceiver). The Argo VI’s audio is rich, inviting enjoyable listening for hours on end. It would certainly be a great pick for long-haul events like Field Day or 24/48-hour contests.

The back panel of the Ten-Tec Argonaut VI (Click to enlarge)

The back panel of the Ten-Tec Argonaut VI (Click to enlarge)


But how does she sound on the other end? Immediately after unpacking the Argonaut VI, I caught band openings on 10, 15, 17 and 20 meters. Though I was only running 7 watts at the time (production units run a full 10W) I received great audio reports on SSB and was even  heard through a pile-up on 17M. Though I believe the default settings would have worked well, setting up the mic gain on this rig is also very easy and straightforward.

As for CW, reports have also been very positive. CW ops will be happy to note that the Argonaut VI has Ten-Tec’s silky-smooth QSK. Frankly, I expected nothing less.

Since I don’t operate digital modes often, I did not test the Argo VI in this capacity. I imagine reviews will emerge soon, but I expect them to be positive as several beta testers were impressed.


When I begin a radio review, I keep a checklist of pros and cons as I discover them to remind myself of my initial discoveries.  Here’s my list from the Argonaut VI:


  • Excellent top-of-the-line audio fidelity
  • Extremely effective DSP variable bandwidth
  • Silky smooth QSK
  • All mode with optional AM
  • Easily accessible primary controls
  • Uncompromised ham band performance (see con)
  • Quality tuning knob and adaptive tuning rate make for easy band scanning
  •  Simple front face and comfortably spaced buttons/knobs (see con)
  • Undoubtedly the best receiver of any QRP rig produced by Ten-Tec
  • Comprehensive and detailed owner’s manual
  • Made in USA
  • Ten-Tec’s US-based customer support, a major plus over many foreign manufacturers


  • No 12 nor 60 meters
  • No internal ATU, nor option for one
  • No internal battery nor option
  • Headphone jack on rear panel
  • Not general coverage (see pro)
  • Learning curve when using multi-functions (see pro)
  • Price of $995 is a little steep
  • RX current drain is high when compared with Elecraft K1/KX1/K2/K3 or KX3, or the Yaesu FT-817

To buy, or not to buy…

The Ten-Tec Model 539 Argonaut VI (Click to enlarge)

The Ten-Tec Model 539 Argonaut VI (Click to enlarge)

I really think the Argonaut VI is a streamlined Ten-Tec Eagle, and a very good rig. Its DSP architecture is based on the Eagle’s (in beta, we even used the Eagle software for the frequent firmware updates).

When I ask myself, “Who will buy the Argonaut VI?” I believe the answer is anyone who wants a QRP radio with the performance and interface we’ve come to expect from Ten-Tec.  If you can live without 12 and 60 meters, then you will be buying a rig that does not compromise on performance. The Argonaut VI is not a QRP radio designed for backpacking like the KX1 or KX3, but it would hang with the best in a QRP contest or on Field Day; operators would experience little to no listening fatigue with this smooth rig.

The Argo VI comes factory-assembled, warrantied, and ready to go, right out of the box.  There’s nothing to put together nor configure.

On a side note, I should mention that this is the first time I’ve beta-tested with Ten-Tec; this provided insight into the process of rolling out a new product and just how responsive and open the company is to both frank criticism and design requests. I believe all of the beta-testers would agree. Every concern I reported to Ten-Tec was eventually addressed by version 1.0 of the firmware.  That’s responsiveness I can really appreciate. Ten-Tec’s Software Engineer, John Henry, is nothing short of amazing. I’m not sure when he finds the time to sleep.

I’m happy to have had this little radio in my shack for the past two months. I’ll have to bid it farewell, though:  Ten-Tec has already sold out of their first production run, so my unit will be returned, upgraded with a new board, tested, inspected, and sold as a demo.  Alas, it’s hard to say good-bye.

I guess the proof is in the Christmas pudding:  I have to admit that I now prefer the Argonaut VI even over my trusty Elecraft K2. So, kind readers, if one of you is in the market for a K2/10 with SSB, and 160M, I may be in the market for an Argonaut VI.

It would bring tidings of great joy, indeed.  Happy holidays!