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Here is a fix for the audio chip heating.? It involves a very simple 7806 voltage regulator mounted on the back of the board.

Enjoy,

Ron W7HD

Hi ubitxer's, I received, I mounted and calibrated my ubitx these days, here in Brazil. And the results:

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1) Low volume of the signals received in the speaker, being necessary to increase the volume at the maximum for some weak signal.

2) TDA2822 FIC heating when it receives some signal measured around 45? Celsius.

3) When I connect the speaker output to another external amplifier everything is normal.

Mods made:

1) Replacement of the FIC TDA2822 by Av2822P manufacturer Avic (used in pc sound) which is also warming up.

2) Installed socket dil 08 on the board for possible replacement.

No Results

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Tests:

1) Measurements of the components around the AV2822P. OK

2) Test with 1Khz @ 1.5Vp signal injector at the amplifier input (pin 7) Ok

3) Test with rf generator (strong signal on the speaker) Ok

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I am believing that the problem may be in the RF step of uBitx.

I'm analyzing

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73 from Junior

-- 
Ron W7HD - NAQCC#7587 OMISS#9898 KX3#6966 LinuxUser#415320
Editor OVARC newsletter

Thanks Ron for the info.

Here the audio circuit is finally ok, everything tested and working.

But ubitx continues with output level on the speaker very low. I have to increase the volume at maximum to receive medium and weak signals.

Now I suspect that it may be a problem in the detector, more precisely the level of the BFO that comes from the SI5351, or the other clock's.

Take the tests here.

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73 from Junior

PY2ADA

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bingo !!!!!!!

Really the problem was it is in vfo CLK # 2

I inserted the rf generator at approximately 52Mhz and now we have the normal operation of ubitx.

Probably some defect in SI5351.

Lucky I have another raduino board.

I leave here my contribution to who in the future find this same defect, and that apparently would be the TDA2822 and was not.

73 de Júnior

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Hi Junior,

Not sure exactly what you did.? I have the same symptoms.? I can hear signals provided the antenna tuner is spot on but there should be substantially more audio.? Reading your note I am not sure exactly what you did to fix it.? Any clarification will be appreciated.?? Thanks Jeff

V4 has lower than desirable audio gain. Add a single stage transistor before or after volume control.
It's fine with headphones.

Raj

Junior

In its design the ubitx in its simplicity is different than other rigs we have used.? I am only understanding part of your discussion. Your ubitx seems to be a v3, not that different than my v4 except for that audio amplifier that you replaced.

The audio IC you provided likely has more output power, but as Raj suggests more audio gain from adding a single stage transistor amplifier would allow a louder output.

If something else undesirable is happening stay alert and clarify it here.

The ubitx is intended for your modification,? be patient and enjoy it.

Curt