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uBITX v6 PTT stuck

 

Hi, folks!
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When I do a digital QSO with my uBITX v.6. it often stucks on TX and won't go back after PTT is released. To put it in Rx mode I have to unplug PTT/Data cable from MIC connector, put the original microphone in and press-release PTT switch on the mike. This started to happened after a year of doing PSK/RTTY with this nice rig without problems. It does'n happened in SSB or CW.
Is there a way to solve this? Is it that PTT relay is "softened" or something else..?
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Thanks for advice.
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Vule, E78CB?
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This is often due to rf getting into the control circuits. Are you using an unbalanced antenna? EFHW perhaps?
 

Hi Vule,
1) Do You have original ubitx V6 display? If Yes, is "TX" sign disappearing from the screen after TX is switched OFF?
2) Is this happening when toggling PTT (also for longer period) with RF power (CW, SSB with modulation) and with microphone?
2) Is powering ubitx OFF and turning it back ON causing back to RX?
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If this is relay(s) issue - then relay replacement might be necessary. I believe better quality OMRON G5V-2 12 VDC might be considered.
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If this is Your PSK/RTTY device issue then will be difficult to help - more data needed - eg. monitoring of voltage on PTT line - as I remember PTT input is configured as pull-up input in Arduino.
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Might be also socket issue.
Might be a problem even with Arduino nano... which of course can be bought without gold-pins soldered, then pins needs to be soldered on the other side than market versions, flashed and installed into raduino board.
Something else...
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Regards
Tomasz
 

I use same dipole that was in use before.. It is without balun but good trimmed and it works same for many years also on other devices, even on the very same uBITX and for same purpose, nothing has changed concerning the antenna... Just thinking, could it be that the relay has worned or weakened out in a year of doing RTTY and PSK contestings..?
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73
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Vule, E78CB
 

Hi Vule,
To start narrowing the issue we would like to know if "TX" is still hanging on the screen while PTT is OFF.
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regards
Tomasz
 

Tomasz, things are like this:
1) I have original screen and TX is disapearing normaly but PTT stays ON and there is no modulation going out.
2) I did not happend on SSB, only on digital, in the biginnig only after longer session or contest, but now even after short sessions..
3) When I power down and power up uBITX TX is still ON. It is only going to off if I enter Microphone jack in the socket and push/release PTT button.
No changes in Power Voltage or different antenna or even a different PC? or cable in between makes difference.. Also, it all works fine in first 5-10 minutes an then start akting like this.
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Is this indicate mostly to these two issues possible? PTT relay or Mic/PTT socket? If it is so, I will concentrate in that way..
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73
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Vule, E78CB
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Vule,

Just replace the front panel mic socket. It may be a problem, just a thought!

Raj

On 07/03/2025 8:41 PM, e78cb@... via groups.io wrote:
Tomasz, things are like this:
1) I have original screen and TX is disapearing normaly but PTT stays ON and there is no modulation going out.
2) I did not happend on SSB, only on digital, in the biginnig only after longer session or contest, but now even after short sessions..
3) When I power down and power up uBITX TX is still ON. It is only going to off if I enter Microphone jack in the socket and push/release PTT button.
No changes in Power Voltage or different antenna or even a different PC? or cable in between makes difference.. Also, it all works fine in first 5-10 minutes an then start akting like this.
Is this indicate mostly to these two issues possible? PTT relay or Mic/PTT socket? If it is so, I will concentrate in that way..
73
Vule, E78CB
 

Hi Vule,
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Raj has more experience with the uBitx than I do. However, the symptoms you describe indicate a stuck K1; here, the Nano is commanding the relay to be off, but the TX is still on and not indicated on the display.
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You can try tapping K1 to see if that clears the TX before power cycling the radio.
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73
Evan
AC9TU
 

Hi Vule,
As TX disappears - I agree with Evan - relay is in this situation is most suspected. K1 is the first from the left, however also K3 - first from the right can also be the case. K1 is switching power between RX and TX blocks, while K3 is switching HF signal between RX and TX part. As Evan proposed remove the cover and try tapping K1 and/or K3 to see if it unlocks - if yes You have suspected relay.
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Mind, replacing relay can be a challenge. Take Your time, don't hurry, try not to destroy pcb traces. There are couple ways to do that.
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Regards
Tomasz
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good movie how to desolder multi via-hole components, also relays:
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regards
 

I changed K1 relay (somehow) so will see how it goes from now. If remain the same I will go for mic socket and also other relay too..
Thanks for the good advices, guys!
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73,
Vule, E78CB

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