Tuesday, April 12, 2022

Post-POTA with the (tr)uSDX

Decoding K5SJC. Black hash mark is only a camera artifact
I activated K-5670 Lake Panasoffkee State Conservation Area (FL) earlier today using my IC-705, Hardrock-50 and tripod-mounted HamSticks on 20 and 40 meters.

Along with me was my pre-built (tr)uSDX transceiver - the subject of this posting. It arrived late yesterday afternoon.

I had intended to use the (tr)uSDX during the activation but wanted to use the IC-705/Hardrock-50 first. Unfortunately, about an hour into the activation, park employees told me that Tuesday mornings are for mowing and that they were about to start.

At that point, I called it quits and drove home.

The (tr)uSDX was still a virgin.

I ordered the transceiver from eBay seller uellyqh who is listed by DL2MAN as a reputable and legitimate seller of this rig. It was ordered on 24 March and arrived very well-packed, and 10 days ahead of schedule, on 11 April.

An hour after placing the order I received an eBay message from uellyqh:

Dear friend, do you need me to program your callsign into the usdx program? If you need, please send me your callsign, thank you.
In addition being fast getting here, the rig had the bootloader, firmware and my callsign installed. Also included was a DC power cable and an SMA-BNC adapter.

After arriving home from the aborted POTA activation, I made some basic measurements of the (tr)uSDX, explored the menu and then hooked it up to my 20m HamStick mounted to the roof of my horseless carriage.

Watts out

Here is the power out (into a dummy load) - indicated (on radio's display) and actual (WM-2 QRP wattmeter) - at the voltages of the two batteries I had on hand.

Pretty close correlation.

Receive current is 70mA; transmit is 1.0 amp.

I called CQ on 20m CW a few times once the rig was connected to an antenna. No responses but the Reverse Beacon Network showed me being heard by several stations.

So I decided to answer, rather than call for a QSO.

First contact was with KB8OOM, activating K-3515 in Ohio. Next was WB8ERJ, also activating a park in Ohio.

One more POTA activator, this time K5SJC, quite loud at K-3051 in Texas.

It works! A 4.6 ounce, 5-band, all mode rig - amazing.

But it's not all good...

I know more than a few people out there are wondering how the (tr)uSDX is on CW.

In my opinion, no one will be engaging in lengthy CW ragchews with this rig...at least not often. There

4.6 oz/130 grams

is an audible "pop" at the beginning of each character. I did sort of get used to it and it is not really an issue for short exchanges like POTA ops. And it isn't loud - but it is unmistakably there.

I couldn't put the AF gain to a level above 10 in the menu. At levels of 11 and higher the speaker emits a raspy tone. This makes the built-in speaker ineffective - the volume needed to be louder in order to hear stations.

With headphones on, level 10 is fine - audio is at a comfortable level and no tone is emitted by the rig.

This is a menu-driven rig. Changing almost any function - tuning step, AF gain, bandwidth, mode - requires accessing the menu. Fortunately, everything there is intuitive and, for operation of the radio, I didn't need to read the manual to know what to do or how to do it.

That will be a different story if I ever want to tinker with the alignment settings. Which I probably will, if I know me...

I hope that if you're considering a (tr)uSDX for your own shack that you won't let these items turn you off. Looking at the Big Picture, this is a tiny, feather-weight radio that will get you on the air on 5 bands for $150. At QRP-plus-a-bit, on a variety of modes. It's not a KX2, nor was it meant to be.

I plan to make a video of this micro-rig in action soon.




  1. Our local club just got our shipment of parts for a club build of (tr)uSDXes. I'm to pick up my kit this weekend. We also had a couple of guys in the club print out enclosures for those that wanted them. They even got fancy enough to try translucent purple and contrasting 'extruded' call signs on the lid.

    Seems like a fun project. I really don't expect a lot from it, except an interesting build, and some portable fun.

    1. The good thing about the orange cases is that you don't have to worry about losing the rig unless you operate from a pumpkin patch.

      Sounds like a good club to be a part of. I joined my local club last week - my first meeting with them is next Thursday. I've met a few members and one is interested in learning how to do POTA ops. Maybe I'' take the (tr)uSDX to the meeting and see if there are any more common interests.


  2. Glad I got you in the log. I was at Kokosing Lake State Park, one of several parks near me. Didn't know you were QRP - well done!

    The (tr)uSDX looks like a cool rig. Going to add it to my collection of QRP radios someday.

    72 and hope to work you again.

    Mike WB8ERJ

    1. Mike, thanks for the contact! Looking forward to reading more of your re-started blog!