(tr)uSDX Forum

I have a pre-assembled (tr)usdx and don't know if the charge pump mod was done to the display. But the symptom I am seeing is odd:

If I am in the menu, there is noticeably less noise than if I am back on the normal display. The only thing I can come up with is that it has to do with the amount of text being displayed?

Is this the symptom of the OLED interference?

Thanks
Karl

Posted under general but probably should have been in troubleshooting. Sorry

Hello Karl,

Would you be able to post/lnk a Vido of your OLED Noise ?
This would help to determine wether it´s normal or not....

73 Manuel; DL2MAN

Hi Manuel,

It's somewhat hard to get a video, but I confirmed that it is the display and the more text on the screen, the noisier it gets. Ironically the smallest amount of screen is occupied by the NR function and is the quietest. Linked below is an audio recording demonstrating what I'm hearing. I don't seem to be able to attach an audio file here.

Beginning — Full noise, normal display
00:00:02 — Click menu button to enter menu (you can hear the click) — hum disappears
00:00:05 — Back to main screen — hum is back
00:00:07 — Back to menu — hum disappears
00:00:10 — Back to main screen — Hum is back

https://drive.google.com/file/d/1TXP5S- ... sp=sharing

Below is processed in Audacity to remove noise so you can see the button presses if that helps with clarity:

relistan wrote: ↑10 Jul 2022, 18:01 I have a pre-assembled (tr)usdx and don't know if the charge pump mod was done to the display. But the symptom I am seeing is odd:

If I am in the menu, there is noticeably less noise than if I am back on the normal display. The only thing I can come up with is that it has to do with the amount of text being displayed?

Is this the symptom of the OLED interference?

Thanks
Karl

Hi Karl,

I had the same symptoms, see my post here: viewtopic.php?p=3176#p3176
The hum was was most noticable on the upper bands, however, this might be due to the lower noise floor on those bands. The strength of the hum was directly correlated to the number of letters on the display. This was a display with the charge pump mod.
So, I ended up replacing the display and also doing the 8V OLED mod (described in this forum). It's much more quiet now and even looks better (bi color)

73 de Jens, DL2RMM

Hi Karl,

I can hear you push the buttons, but I don´t hear OLED....
Sorry, this is normal behavior.
Just look at the Schematic, how simple the rig is. Sensitivity to Noise is the Price we pay for it´s simplicity....
I suggest: Connect an Antenna, and listen to some signals. You probably won´t be able to hear it in a live enviroment anymore.

73 Manuel; DL2MAN

Hi Manuel, Jens,

Thank you both for the help.

No worries, if this is the normal behavior I am fine with that. But, if it was that it needed the mod, I would open the radio up to investigate. But didn't want to dig into a working radio for no reason. Great little rig that I have been listening to lots of signals on. In general the sound is quite good, but since I noticed this I thought I would ask.

Thanks again

Karl

Is there any reason not to simply add an on/off switch for the display to shut it off when not needed in order to stop noise? It would also save power. I'm mounting my rig in a somewhat larger metal box, so a switch for the display would be no big deal. I was already planning on it as an energy-saving mod.

Yes there is.
The OLED needs to be initialized correctly.
This is being done at startup.
If you just switch it off and on, it would show garbage until proper re-initialisation by atmega.

73 Manuel DL2MAN