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uBitx V4 no modulation in SSB #ubitx #v4

sq6poh@...
 

Hello everyone
I am new here, I have been using my uBitx for about 2 years. In general, everything was fine until you try to build AGC.
Radi has lost a lot of tenderness. I have the impression that the audio track does not work. The transmitter switches on but no signal comes out. The transmitter is rather efficient because in CW the power is correct.
I checked and even replaced Q6, Q70-Q74.
He has no further ideas.
 
greetings
Karol SQ6POH

MVS Sarma
 

Karol,pkeease tryvto check and replace if faulty  bat54s at demod level. This is an smd with 2 diodes in series.
All the best 
Sarma vu3zmv



On Tue, 14 Apr 2020, 5:44 pm , <sq6poh@...> wrote:
Hello everyone
I am new here, I have been using my uBitx for about 2 years. In general, everything was fine until you try to build AGC.
Radi has lost a lot of tenderness. I have the impression that the audio track does not work. The transmitter switches on but no signal comes out. The transmitter is rather efficient because in CW the power is correct.
I checked and even replaced Q6, Q70-Q74.
He has no further ideas.
 
greetings
Karol SQ6POH

sq6poh@...
 

Hi
Thank you Sarma vu3zmv for the answer.
I do not have such a diode on hand, but I soldered the current one and the measurement indicates that it is probably working.
I didn't mention it before but I have an additional built-in amplifier on MAX 9814 between VOL-H and VOL-M. When I remove it, I can't hear anything.
I'll order the LEDs and keep looking.
 
Best regards
Karol SQ6POH

Evan Hand
 

Does the radio receive work?  If so, then the BFO and the diode IC are OK, as it is used for both transmit and receive.

Since the problem started after making the modification for the AGC, can you undo that mod and see if the radio works?

I suspect that there is an error in the AGC modification that you made, as that is when the problem started.  It would also help members in this group to know which AGC mod you installed.

I do not understand how the MAX9814 electret microphone amp is being used.  That would normally not be wired to the VOL signals for the receive volume control.  Are you using the electret amp as a preamp for the receive audio?  The information that you are giving me is confusing.  Is it possible to post pictures of the modifications that you made, or better yet sketches of the circuit schematic on how the modifications were installed?  This for any and all modifications that you have made in the audio sections of the radio. 

I would start with just the receiver, and get it working again before going on to the transmitter.

73
Evan
AC9TU

sq6poh@...
 


welcome back
The case turned out to be very simple. During tests, the L5 mechanical coil was damaged. The receiver worked but very poorly. I repaired the electrical connections of the coils and additionally glued with hot glue.
I don't know why I didn't think of it before. I had a similar defect after receiving the package.
The modification with MAX9814 significantly improves the volume on higher bands but also works great at 80m or 40m.
 
Once again, thank you for your support
Best wishes
Karol SQ6POH

Evan Hand
 

Thank-you Karol!  I had not thought to use this module in this way.  I will try it out on my rigs to see how it works for them.

I am glad that you found the problem with your rig.  
73
Evan
AC9TU

Vic WA4THR
 

I used the same technique as Karol on my V4, but using the circuit from the July 2019 QST article. Using the circuit as a preamp fixed the low audio common with the V4 and provided a very good AGC. I would be interested if this works on other versions of the uBitX as it is certainly an easy installation, and this prebuilt circuit would make it even easier at a very nice price.

=Vic=