Problem on SSB

[DD6FM]

Hi
I have a problem .. on Ssb it sounds very strange .. I made a video.. on FM it seems ok


https://youtube.com/shorts/j2vlKyNT-zQ?feature=share


Someone can help ?
73
DD6FM - Marco

[Faraaz VK4JJ]

Has this been checked with another ham, or via a remote sdr?

[DD6FM]

I can’t reach a WebSDR from my home … i took my icom also outside in the Garden and record myself, so the distance was larger

73

[mm0gyx]

Hi
I have a problem .. on Ssb it sounds very strange .. I made a video.. on FM it seems ok


https://youtube.com/shorts/j2vlKyNT-zQ?feature=share


Someone can help ?
73
DD6FM - Marco

Audio with my rig also not great, but in your case I can’t tell if it’s the same as mine. One thing, you have the receiver speaker feeding in to the mic, positive feedback! Did you listen the the rx using headphones?

Ian MM0GYX

[DD6FM]

I used the record function on the receiver. It was the same there… and I don’t used the speaker Mike on icom .. it was the internal speaker

[pe1nnz]

Hi Marco,

On a near-field receiver, the SSB signal is so strong that the small artefacts of the digitally processed signal in the (tr)uSDX becomes audible. In a normal QSO setting there is so much path-loss involved that these artefacts are well attenuated below the noise floor and hence not observable.

Note that every signal that is digitally processed has this limitation, it is called quantisation noise and these are noise signals in the background of the main signal. It is only when you start amplifying the signal that this noise becomes apparently observable.

To test the SSB/AM signals on a near-field receiver, the recommendation would be to use an attenuator of 60dB or more in-front of the receiver.

73, Guido

[DD6FM]

Hello Guido
Ok i will test it .. but I also took my icom to my garden many meters away with record function and it was no change ….

73
DD6FM - Marco

[dl1bax]

Hi.

Here is my Modulation Test with 4 Watt on 80 Meters from Home (near Bremen) to Hackgreen Web SDR.
About 350 km Distance, 80 Meter at 02:00 UTC.
The Recording is from Hackgreen.
First extern Elecraft MH-3 Mic, than intern Mic.

Wahl do you think, is the Modulation OK or is there more to go?

Regards
Ralf, DL1BAX

The file is to big für upload, follow the link.
https://c.gmx.net/@329576975595208930/x ... yhqH8y_RNg

[DL2MAN]

There is definately something on the Voice that´s not supposed to be there.
Not too bad, but also not optimal.
If all the components on the mainboard are right, and have good solder joints, please check
your power supply.
I even had once a cheap chinese Laptop-Power Supply (in the Room - not connected to (tr)uSDX) that would radiate into the (tr)uSDX while TXing, and pick up the Noise and radiate out.
(tr)uSDX was running on Battery.
I could reproduce that every time:
Power Supply connected to Wall Plug -> TX Noise
Power Supply Disconnected from Wall Plug -> No TX Noise.
So check your enviroment for potentially noisy stiff, like cheap switching Power Supplies, LED Lamps and enything else, that can cause trouble.
Test another mic (eG externally) and if nothing else helps: Try to change Atmega... They also have quality differences.

73 Manuel; DL2MAN

[wa2t]

Hi Guido and group,

Attached is an audio clip from my (tr)uSDX. It is in QSO on 80m with a friend of mine (who recorded the audio with PowerSDR and emailed it to me) who is about 200 miles away from me. I am using a Baofeng Mic (with corrected 3.5mm connector pinout). The Baofeng mic sounds the best out of 1. Yamaha CM500 computer headset with mic and 2. The internal mic of (tr)uSDX.

https://www.dropbox.com/s/ifztb1uib0y2u ... B.wav?dl=0

Thanks and 73,

Robert, WA2T

[DL1DBY]

I noticed something interesting on an older uSDX-Sandwich, but this will most probably apply to the (tr)uSDX as well:

When connecting the uSDX at home to a dummy load with a short but very cheap antenna cable, the audio received with an external receiver and a telescopic antenna close by sounds very bad, when I use an Baofeng microphone. However, since I bought a high quality antenna cable and used it in the same setup the audio signal is much better.

It seems that the cheap antenna cable was radiating and the Baofeng microphone (with the microphone and antenna jacks close to each other) is very sensitive to that. For example, I cannot use this type of Baofeng microphone with DMR handheld radios with their aggressive digital signal. I have to use better microphones with DMR radios.

[Ohwenzelph]

My vote is that DL1BAX's audio sounded better with the internal mic than with his elecraft mic.
The electrets have an amazingly accurate flat response to sound. For ssb we are really only interested in ~300 to 3000 Hz. "Good" hi Fi audio stuff is 20hz to 20khz or better, which is "normal" human hearing. The (tr)uSDX internal mic is spec'd for 100 to 10,000 Hz. As you get older you progressivly lose the higher frequencies. (I can't hear much above ~10khz.) Bob Heil has said frequencies around 2 to 3 khz seem important for understanding speech. In low power radio we waste a lot of energy when we reproduce lower frequencies that don't add much to intelligibility.
Maybe the audio would sound a bit better if we rolled off some of the base end with maybe a cap and a resistor on the mic line as in http://www.w1aex.com/mic/mic.html
What do you think?

[DL2MAN]

We received a kit from Sunny to investigate the following situation:
On transmit, modulation volume is too low with the on-board microphone. After replacing the microphone with the one supplied in the kit, the issue is resolved and modulation is good.

The bad microphone seems to have different parameters (diode-voltage threshold of 980mV instead of 850mV). We found that the microphone needs to be carefully handled when soldering; excessive heat on the pins can desolder the components inside the microphone (which I found to be the case after opening the microphone).

Long story short:
In case of bad modulation, try replacing microphone. Handle Mic capsule with special care !
73

Manuel and Guido