The Polar Explorer – A High-Efficiency Transmitter

The Polar Explorer is a high-efficiency HF transmitter that produces 500W output. By increasing the power efficiency to 80-90%, The Polar Explorer seeks to reduce the cost, size, and weight of mid-power HF transmitters.

Originally conceived in partnership with Brian, K1LI, and with the ongoing help of Jeff, N1RD and Jeff, N1TK, the project has reached critical mass. It's now time to test the waters and see what sort of interest there might be in others using and evaluating the design.

Our website at www.polex-tech.com is now live to share the adventure!

Please take a minute to visit the site, read about the history and progress of the project, take a brief survey, and learn about opportunities to become a Beta tester.

We will be making a presentation at the upcoming NEAR-Fest XXV hamfest in Deerfield, New Hampshire on May 3-4. Visit the Near-Fest site near-fest.com for the exact time and location. We will also have a table where you can stop by and ask questions about this exciting new technology.

Then it's on to the Dayton Hamvention on May 17-19. Be sure to stop by Booth 6810 and say hello, learn about The Polar Explorer, and find out about our Beta testing program.

73,

Tony, K1KP

 

I added a few more slides to the slideshow - take a look!

-Tony, K1KP

 

This sounds like it might be a really nice upgrade to one of the many SDR receivers floating around. The user could pick the receiver of his/her choice, and then pair it with the transmitter for a full station.

 

The addition of an SDR to The Polar Explorer seems like a 'no brainer', and we're constantly evaluating that option. Ultimately, marrying this new high efficiency transmitter technology with a high quality receiver would create a very attractive transceiver. The problem encountered is that most off-the-shelf SDRs require the horsepower of a full-sized PC to realize their full performance potential. Additionally, most cost-effective SDRs have unacceptable latency in the receive path. While latency of 150msec or more is fine for the primary use of these SDRs, which seems to be to add spectrum display capabilities to an existing transceiver, high latency is unacceptable for the actual station receiver in transceive operation, especially for CW.

We'll keep looking, and if something better comes along, we'll give it a try!


73,

-Tony, K1KP

 

Just to clarify, Software Defined Radio, SDR terminology does not apply only to receivers, but equally to transmitters. So, the Polar Explorer could be modified to be an SDR Transmitter, in concept.

 

Nearfest was a great success! There was lot of interest and excitement in the Polar Explorer and several prospective Beta Testers signed up.

Now it's 'On to Dayton' - if you're making the trip, be sure to visit the Polar Explorer Booth, #6810!

-Tony, K1KP

 

Curious what kind of power consumption it has. I guess it has its own power supply but if hooking up to my own 12v source, whats the amp pull on standby and on transmit?

 

Yes, the Polar Explorer has a built-in supply that operates from standard power line mains (120/240 VAC). A conservative estimate of power line consumption would be <750W in transmit, and probably <20W in standby. Currently it does not operate on 12V DC. The internal supplies are switching supplies so different internal supplies would allow it to work on 12VDC, but in transmit that would require >50A (at 13.6VDC). Note that quoted efficiency numbers are Power Amplifier Efficiency (PAE), so they do not include losses & overhead in other circuitry. And remember, it's a transmitter, not an amplifier!

Tony, K1KP

 

The Polar Explorer was very well received at the Dayton Hamvention! The booth was packed on Friday and Saturday with folks learning about the new technology transmitter. It's gratifying to see how quickly the average ham 'get's it', recognizing the real practical advantages that a high efficiency transmitter can offer in size, weight, and cost. Over 500 business cards were handed out, and several more hams signed up for the Beta testing program.

Two videos about the Polar Explorer have been posted to Youtube. The first one is from a live Dayton Hamvention 2019 video chat with W5KUP.COM:

(fast forward to 20:50 for the beginning)



The second one is from the Nearfest, NH flea market:





Tony, K1KP

 

What is the actual amp draw in a 120V and in a 240V circuit? I think I read everything and apologize if I missed it. Thanks.

 

per the previous post and doing a little math, 750W/120 VAC = 6.25 A (RMS ) for peak output...

 

Assuming Power Factor = 1.0
Which it rarely is with switching power supplies.

 

Also, per that previous post:

"A conservative estimate of power line consumption would be <750W in transmit, and probably <20W in standby." (Red, underlined text for emphasis)

It's safe to assume these easily measured values haven't been measured. Why not?

 

In the real world we would put an amp meter on it. Please do that and let us know.
Yes, we know it is a transmitter not just an amplifier, but we do want to know the total amp draw at 500W output key down.

 

OK guys!

So, I'm very focused on the efficiency of the PA, and I have literally thousands of measurements of DC power in vs RF power out. The transmitter is my area of contribution; the power supplies, not so much.

The Polar Explorer uses two 350W off-the-shelf switching supplies to supply the DC for the PA. They are spec'ed at 89% efficiency, and of course being switchers the power factor is not wonderful. But with 89% efficiency their real input power should be in the range of the 750W number I listed.

I have a TEK 2645B scope and an HP 3585A Spectrum Analyzer, but do not own the instrumentation needed to accurately measure real AC power...

Why is that such a concern? It's significantly less than the Elecraft KPA500, or the AL-811...

-Tony, K1KP