Activation with (tr)uSDX on Schauinsland DM/BW-008

Today it was a quick and spontaneous trip to the Schauinsland DM/BW-008 with Stephan @DC8LZ. We wanted to get our new (tr)uSDX transceivers into the air.

A built-up kit.

The weather was appropriately wintery at this time of year.

After a short hike to the summit the antenna wire was tightened and we could start. We used a simple wire antenna (UL stranded wire) together with an Elecraft T1 tuner.

We used the integrated loudspeaker for the audio output. The quality is not that great, but it was enough. Also Stephan used the integrated microphone for SSB and not an external one.

Stephan @DC8LZ

Marcel @DM3FAM

Many thanks to our chasers for your patience and good ears. It was exciting for us to be SOTA qrv with the new transceiver and it will probably not be the last time.

See you again soon.

73 Marcel DM3FAM es Stephan DC8LZ


Thanks Marcel for the report.

Great winter scenery :cold_face:

Would be interesting to get some feedback on audio quality and readability of the signals from the new radio.
Maybe your chasers can elaborate.

73 Joe


Congratulations on the successful test of your new trx. I am very pleased that we had an s2s contact in cw.

We can only dream of all that snow here in northern Germany. But the cold wind is also giving us a hard time.

Bye for now, Chris

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Hi Marcel & Stephan,
it looks like you had far more snow than me. I was on Žigartov vrh (S5/PK-005):

The weather actually turned out OK, considering the forecast. My new Paramo Enduro Salopettes arrived today, so I can get out on the skis again this winter. I like your poncho, by the way; nice handy shelter if the weather gets bad.
73 de OE6FEG


Cool, looks like fun this super small TRX!

I would be also interested how good the audio is, both RX and TX. I guess it doesn’t have a compressor, right?

The last time I activated on Schauinsland was also with snow, so I could also use the table for myself :grin:

73 Stephan

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Well done, Marcel and Stephan :+1: You really had some snow up there!
Unfortunately I missed your spots. It would have been interesting to listen to your signal. Next time maybe?
Cu soon :wave:
73, Roman

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Hello Stephan,

it comes with a kind of compressor I would say. But I ask Guido how he would describe this. I will come later with more details. Since the signal is completely digital prepared and optimized it has a bit “bunch” I would say. :wink:
If you look on the old block diagram you could imagine that there use some nice stuff in it:

But the truSDX comes with approvements in the SSB code in comparison to the uSDX (and on many other parts of the code). We just have no new block diagram and so on…

I guess I could send you a web sdr record for personal use only between DC2O (Op DL2FZ) and DL2MAN, recorded in UK.

One thing about the TX quality in SSB where the audio comes over the mic:
The mic has a very weak signal and imports noise and “garbage” which you may hear in the very near of the TRX. This overlay of the “good voice” signal and the garbage sounds bad in the near since you can hear this there. But with about 60 dB ATT… the normal loss at the remote side… the garage is too weak and the SSB signal sounds great!

If you for example do some ft8 the signal is much better because of the better signal input quality.

Over all the SSB quality in TX is good. Just don’t worry if you make a local test at home. There it sounds not that good. Check it on a websdr for example. Or joins the next truSDX on the air summit.

Best 73,
Stephan (,too)


Ok… The information about the question about the compression:

“…when you select in menu TX drive=1 then you follow almost linear amplitude curve and there is no compression. But if you increase it it will be more and more compressed, at tx drive 8 it is so compressed that there are no amplitude variations anymore, only a constant carrier or no carrier (when silent), in that case voice information comes only through phase modulation (good for high peak power envelope but at the cost of signal quality).”

73, Stephan


Hi Stephan,

Thanks for your explanations!

Probably the best would be to hear it myself on the air, with focus on its internal microphone, but a comparison with an external one would be also interesting. I don’t plan to build a truSDX myself, I’m just interested in general about such TRX.

This sounds like fun!

73 Stephan (as well :wink:)


So much snow in the Black forest. We are getting jealous here in the Palatine forest. Great activation under severe conditions. I will build a (tr)uSDX this year myself and look forward using it for my first activation.


Hi Joe @OE5JFE

thank you. Yes, it was fresh there :snowflake: :ice_cube:

The only thing I can say (as activator) about the audio is that it was a bit scratchy due to the speaker. The volume was also limited. But with headphones no problem. If the ambient noise is kept within limits, it also works well without. The signals I could hear were flawless.Listening to Stephan in SSB was also good. We may plan to be QRV separately on a summit with the (tr)uSDX. Then we will try to record and compare the audio and such.

73 Marcel DM3FAM


Hello Chris @DL1CR. Very nice to hear you in a s2s cw QSO :+1: Thanks for calling. See you again soon in a QSO.

Matt @OE6FEG. It’s a pity we didn’t hear each other. You seem to have had a nice place.

We had to clear ours first. Unfortunately, I had forgotten my “on the road” shovel.

Stephan @HB9EAJ. We’ve left you some snow for your next activation on the Schauinsland :wink: :wave:

Yes Roman @DL3TU. I would be happy if it works out again next time :+1:

Christian @DL1GKC. Good luck and have fun with the assembly. Maybe we’ll hear you soon in a QSO with your (tr)uSDX.

73 Marcel DM3FAM


Hi Marcel,

Thank you for fine report and QSO as well :wink:
You have nice trx, small and convenient !

73, Jarek

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