(tr)uSDX - initial thoughts (Part 1)

[SP9TKW]

I am sorry Guys, but I am not sure what are you complaining about.

This is 55-60euro radio. It works, it doesn’t send spurious signals. Yes audio is a bit off on internal speaker, so connect headphones. It works, it takes next to nothing to run it (battery), it fits into pocket, and you can build it by yourself.

IMO perfect package for starting SOTA activations by person who doesn’t have huge budget to spend or for few day hikes when weight is an issue.

I done already 4 activations both SOTA and POTA and nobody complained about audio using internal mike. Is it perfect no its not, but does the job.

I assume that we are talking about (tr)uSDX from approved source and not some Chinese knock off.

73 Marek

[G4TGJ]

@SP9TKW

This is 55-60euro radio.

Is it? A quick google suggests it is at least 90 Euro for a kit.

[K6ARK]

I must say, I appreciate the realistic, honest assessments folks here are making. I have used the analogy of the Baofeng HTs for these kits.

The Baofeng UV-5R is a terrible performing radio compared to a solid offering from one of the big three manufacturers, but it’s also an incredible device for $25 US, and it well enough in many use cases.

Likewise, the (tr)uSDX is a terrible performer compared to any of the commercial QRP radios, but for under $100 US, and as an SDR running from such simple hardware, it is pretty amazing.

It’s fun to tinker with and great as a backup or occasional use rig, but I would never recommend it as someone’s primary portable station.

And I’ll admit, I too am disappointed by the licensing limitations assigned to the design.

I’ll leave you all with an image of my recently built high-band truSDX with matching custom paddle.

Adam
K6ARK

[9A3BKF]

Thats the price in a group buy situation.KIt only afaik.

[EA2BD]

Hello,

I bought one trUSDX in kit form and built it myself (from EA3GCY approved supplier).
Soldering process was fun and not that huge, although it’s not a kit for a novice. I had some troubles first and fried the BS-170 transistors due to a bad enammel removal in the SWR measuring circuit toroids.

It was good that no alignment was necessary appart from the frequency adjustment easily accomplished by centering the CW carrier on my IC-7300 spectrum monitor.

I would support the pros and cons listed by Richard at the beginning of the thread.
As for me, this will not be my primary radio as I’m lucky to have better options in my gear, but anyway, it was a thing to get and try for the price.

After a few days of usage here at home I feel this would be an okay CW rig, and a worse rig for SSB.
I find SSB transmission dirty, as others have said, and this is the most annoying feature I find in this rig.

I tried to improve the transmitted audio quality by using an external microphone and played a bit with the only two parameters that influence on the SSB quality that I find in the menu: Noise gate and TX drive settings. Their default value is 4 and 4 for both.

On-air testing monitored by my friend Jorge, EA2LU suggested that:

• internal mic sounds much poorer when compared to an external mic
• the settings at 4 & 4 level were a bit too agressive and over compressed
• reducing these settings to 1 & 1 produced less distortion and artifacts, although they should influence on output pwr a bit.

I recorded an audio file to compare several situations. You can hear it below:

• Part 1: internal mic / Noise gate 4 / Tx drive 4
• Part 2: internal mic / Noise gate 1 / Tx drive 1
• Part 3: external mic / Noise gate 1 / Tx drive 1
• Part 4: external mic / Noise gate 4 / Tx drive 4

Additional optimization could be achieved by using different settings, perhaps a different combination of both.

Audio file: (recorded on my IC-7300 without antenna, preamp off, attenuator on, RF gain reduced)

trUSDX Micro comparison EA2BD.mp3

In order to plug my Sennheiser computer headset (PC 3 model) I built an easy interface to get the correct pinout and added an external PTT hand switch:

I now need to take it to a SOTA activation and see how it deals in the field…

73 de Ignacio

[G3CWI]

Would you buy or build a truSDX based on current performance?

• YES
• NO
• Maybe
• Already own one

[M1BUU]

I was thinking about buying one, but I have decided not to. I don’t do much SSB anyway.

Interesting topic, I’ve enjoyed reading about people’s experiences with the radio.

73, Colin

[EA2BD]

What a shame Colin, its bright orange case just fit perfect among your collection on stock!

73 Ignacio

[VK1DA]

I made the first six cw qsos of an activation today using the trusdx. I had to reduce af gain below 13 to stop an audio oscillation from masking the incoming signals. Reports were good.

I had preset the key to paddle, iambic a. 16wpm.

My main concern is reading the screen outdoors. Today was an overcast day. This will be a significant problem for me on brighter days.

Conditions were decidedly poorer than in recent times. 20m got me some vk and one zl contact. 30m netted on4vt and some vks. 40m produced 20 contacts on cw (6 with usdx) and on ssb using kx3.

73 Andrew VK1DA/VK2DA

[G3CWI]

The truSDX team has started giving them away. Terms and conditions apply. (tr)uSDX give-away - (tr)uSDX Forum

[VK1DA]

Giving one away, to the winner of a poll.

[JP3PPL]

Hi Adam. You should have chosen the RIVER PLATE colors instead of BOCA JUNIORS!!! (just a joke, true football fans will understand)
Where did you buy the components and what results did you have, if you tested it, in the spurious emission?
73, Takeo

[EA2BD]

Hello,

Today I went to Mt. Measkoitz EA2/NV-097 to try and test my truSDX.
I used a random wire antenna plus a ZM-2 tuner.

I ran it on 10 MHz CW, then 14 SSB and last 7 CW.
I logged 18 qso being 5 S2S.

Some of the qso were easy and pleasant, and some others a bit tricky, specially these where I had low level of the incoming signals.

Was that comparable to any of my “regular” activation using other brand rigs?
No. I would highlight the following items:

• there was noise in reception, variable in tone and strength depending on the freq, but taking into account my summit was remote and free from noise sources it was a bit nasty and I had troubles to hear the little signals.
  Floor noise is an issue here.

• As Andy (VK1DA) pointed, the display was difficult to read. Today it was bright plenty of sun and, despite I tried to shade the rig behind the thick trig point, the oled backlight was too low to read it with ease.
  The little font size in the display was also challenging, specially to read the SWR info.

• CW worked a bit better, but I think I had a bit of RF coming back from my random antenna and therefore theew was key clics and buzz between letters while sending.

• I used earphones all the time and had a good audio level. If you increase it more than level 12 (not really necessary) the same oscillation than without the earphones begins.

• I had no complains of my TX audio, but I would like to know how I sounded like in the other end. Noise gate and TX drive were set to level 2. I used my PC headset and mic interface.

Overall I achieved a good result but I had to concentrate at some qso to deal with the noise.

Adjusting for minimum SWR was a bit stressful as I tried to avoid a too high level while adjusting the tuner and checking the tiny and faint text on the display, against the sunlight.

The rig works, but it is not comparable to any of the popular rigs we use for SOTA, although this one shows very little weight and current draw.

I’d say that activating with the truSDX is challenging, and perhaps it’s of appeal for somebody.
As for me, I think I would rather prefer using it as a backup, on some holidays as it’s small to pack and use, casual style.

73 Ignacio

[EA3BV]

I think the only “holy cow” at today is the QCX, I own two and built three and actually they are my primary rigs for sota (QCX+ 20m and QCX mini for 30m).

Another very very good performance ratio price y a new EGV+ (40,30,20) from EA3GCY

EGV+ Three band CW

Perhaps the trusdx for enjoying while building yes, or as a backup, etc.

[M1BUU]

The QCX is OK, but it’s not pleasant to use with differing signal levels. The AGC option improves things a bit but the AGC revovery time is too slow.

For the price, the QCX is very good value and interesting to build. There’s much to like about the QCX - the extensive feature set and competent keyer, however I feel the receiver is not as good as it could be.

I like the MTR receiver, however that’s not perfect either, as it could do with more AF gain and a volume control.

At the end of the day, the perfect SOTA rig hasn’t been created yet but there are some good SOTA rigs out there.

73, Colin

[EA3BV]

Colín,
Of course MTR is better that QCX, I owned a mtr3 LCD. But It costs three times plus than QCX.

[G3CWI]

I noticed something interesting with my truSDX. When I used the same bag that I used for my KX2, by the time I included a battery pack, atu (T2), a 4:1 transformer and the leads for the above, it actually took more space than the KX2.

[KI4POT]

I don’t try to make my truSDX the operational equiv of my KX2. Instead, I leverage its strengths (size, lower power requirements, etc) to build a smaller, lighter kit.

My truSDX kit is a full pound lighter than my KX2 kit:
truSDX: TX, battery (same type for KX2), earbud for RX-audio (I use the internal mic for TX), and homebrew 40/20 EFHW antenna with micro-transformer. Weight: .8lbs

KX2: TX w/ATU, internal battery, Sony earbuds for TX/RX, BNC adapter, 57’ wire, 17’ wire. Weight: 1.8lbs.

Both weighed on my digital archery scale (made for measuring draw weight, but works great for weighing static loads).

Volume-wise, the truSDX kit is a bit larger than a baseball. The KX2 kit packs up snugly in a Lowepro CS40 case. The truSDX kit fits in my bike’s handlebar bag, the KX2 kit does not.

Chris

[AD5A]

I use a home brew, resonant, 4 band trapped EFHW, following the plans on the QRZ page of K1JD. So carrying a radio with an antenna tuner or a separate antenna tuner is redundant. I used the (tr)usdx on an activation in NM about a week ago with good results. With the help of K1JD, I changed out the display to one with white digits, which worked fine outdoors. I only do CW, so SSB issues do not effect me. Volume is very good at 11, with earbuds, clear signals and 23 QSO’s in about 20 minutes. I used my KX2 on the next activation, about 1.5 hours later and made 23 QSO’s. I understand the variability in propagation, but by comparison, this is acceptable to me. The (tr)usdx RX is sensitive enough to compete, in the real world, with other radios of its genre and puts out a solid 5+ watts @12V. I’m not a real techie, I only focus on results and they were fine. The weight factor difference compared to a KX2 is significant, given I use resonant antennas. Regularly hiking up to 8 - 10k feet ASL, weight matters.

I have MTRs and they are more refined, but they lack an SWR meter, which gives me some comfort in the field. The new MTR 4B V2 has an SWR meter, but the radio is a bit more bulky than the typical MTR. The QCX is good, but I have to carry 2 of them to cover 3 bands. The (tr)usdx ticks off a lot boxes that suit me.

If anyone doesn’t want theirs, you can sent it to me:-)

Mike AD5A

[MM0YCJ]

@AD5A

If anyone doesn’t want theirs, you can sent it to me:-)

Or me?

Ciao