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ubitx will not transmit.

 

Folks, I bought the radio kit, built it and I don't believe I was ever able to transmit.? I have another radio and I can receive on the ubitx but nothing I do makes a transmission.? I bought a crummy baofung microphone and cut off the speaker connector.? From what I could tell the 3.5 connector is supposed to be wired correctly for the ubitx.? When I plug the mic in the red light on the mic is on.? When I push to talk the red light goes out and the TX lights up onthe display.? However, I do not hear anything on my other radio.? Is there something simple I am missing.? It has been ages since I looked at this thing and now I am somewhat regretting it again.? It has been nothing but a headache.? But I thought I would give it a try again.? Thanks for any help you might be able to provide.
Andrew
 

It didn't come with a microphone?

Gordon KX4Z


On Tue, Apr 22, 2025 at 9:30?PM bigdaddy via <bigdaddy=[email protected]> wrote:
Folks, I bought the radio kit, built it and I don't believe I was ever able to transmit.? I have another radio and I can receive on the ubitx but nothing I do makes a transmission.? I bought a crummy baofung microphone and cut off the speaker connector.? From what I could tell the 3.5 connector is supposed to be wired correctly for the ubitx.? When I plug the mic in the red light on the mic is on.? When I push to talk the red light goes out and the TX lights up onthe display.? However, I do not hear anything on my other radio.? Is there something simple I am missing.? It has been ages since I looked at this thing and now I am somewhat regretting it again.? It has been nothing but a headache.? But I thought I would give it a try again.? Thanks for any help you might be able to provide.
Andrew
 

Gordon,
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I thought the original uBitx kits did not include a case or a wired mic.? ?It was not until the v6 that a case from HFSignals was offered.
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Andrew,
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So, the question is, what version of uBitx are you using that is having transmission failure?? What test equipment do you have to find the issue with the radio?? Are there any changes or modifications from the factory-supplied radio?? If you are unsure, post pictures of the mainboard of the radio.
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Here is a picture of the v6:
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I usually start by measuring the transistor voltage, beginning at Q90 and proceeding through the RF amplifier stages.? Raj, VU2ZAP, has posted the voltages for the v4 transistors in the files section of the group:
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The same process and voltages work for the v3 to v6 versions.? Ensure that the correct conditions are set when measuring the transmitter.? The setup is included in the spreadsheet.
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I then test CW operation to determine if the issue lies in the power amp or the SSB sections of the radio.
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73
Evan
AC9TU
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Evan,
Thanks very much for the gracious reply.? Sorry for not providing more information.? My board is exact as the one in the picture you posted.? ubitx V6 .2.? There have been no changes or mods to the radio.? I have quite a few tools available for troubleshooting:?? multimeter, oscilloscope, frequency generator, etc.? I will check the voltages as you suggested.? The microphone gave me so much trouble that I never knew if the radio was not working or it was the microphone.? It made the troubleshooting process very frustrating.? I just wanted to find something where I could get a click of some sort to verify there was a transmission.? I will report back on the voltages.? Thanks again for the helpful suggestions.
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Andrew
K1BDA
 

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Great!!

On Apr 23, 2025, at 17:25, bigdaddy via groups.io <bigdaddy@...> wrote:

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Evan,
Thanks very much for the gracious reply.? Sorry for not providing more information.? My board is exact as the one in the picture you posted.? ubitx V6 .2.? There have been no changes or mods to the radio.? I have quite a few tools available for troubleshooting:?? multimeter, oscilloscope, frequency generator, etc.? I will check the voltages as you suggested.? The microphone gave me so much trouble that I never knew if the radio was not working or it was the microphone.? It made the troubleshooting process very frustrating.? I just wanted to find something where I could get a click of some sort to verify there was a transmission.? I will report back on the voltages.? Thanks again for the helpful suggestions.
?
Andrew
K1BDA

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