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No ssb out in ubitx v3 #ubitx #v3 #power


Nikhil B
 

Can anyone tell me what the problem is?
Problem: no power in SSB mode.
Ubitx V3
 
When i push the ptt the rig go into tx, i can hear the relay clicking, current draw increases to 680mA. But on talking no current increase. No output power.
In CW mode there is 5watt power with tone.
 
I checked the mic, mic connector, wires and connectors to the board, any bad solder joint. All ok.
 
What maybe the reason no power in SSB mode?
 
I am new ham and this is my first rig, please help.


Nikhil B
 

When i keep my other SSB reciver in the room and talk, i can hear my voice on that receiver. But watt meter show no power. What is the problem? Which part do i need to check?


Evan Hand
 

Nikhil,
It is common for SSB to show low values on a wattmeter.  Try providing a constant tone, or a long Heeeeeelloooooooow.  In another thread, there is a website that has an audio tone generator.  You can use that with a 1kHz and the mic close to the speakers.  Try different volumes and distances to see if the power out changes.  If so, then most likely you have a low audio drive from the mic.

I solved the low SSP audio by getting an amplified mic and using that. Others have gone to a preamp in the rig enclosure, and for the high end, a speech compression amp for maximum punch.  I have not that, so you will need to search the groups.io site or the internet for speech compression uBITX.
https://groups.io/g/BITX20/message/76912

Hope this helps a little
73
Evan
AC9TU


Evan Hand
 

Nikhil,
I forgot to point out that if you are not hearing SSB signals correctly when receiving, that you could also have a BFO tuning issue.  If the BFO is too far off the SSB filter will attenuate the audio and you will also not get much output.

I would check it with this link:
https://www.hfsignals.com/index.php/bfo-tuning-aid/ 
it does require a mic connected to your PC and works best with the Chrome browser.

73
Evan
AC9TU


Nikhil B
 

Thanks Evan for prompt reply, but i dont think mic drive is an issue here because with the same setup earlier it was pushing 5 to 7 watts on ssb.
Then it was sitting idle for 5-6 months away from any RF source. Now when i power it on with same setup, no SSB.
Wattmeter i am using is sensitive for low 1watt.
I tried long Helooooowwww, no power.


Nikhil B
 

BTW when i say no power i mean zero power (no means to measure miliwatts).

With my limited knowledge i think, SSB signal is generated, converted to RF signal but that RF signal is not getting amplified to give more power.

As CW is giving 5watts, final IRF must be ok. Problem lies somwhere in between.


 

Does the RX work ?

If that is Ok then start with D1/2/5 Q20/21/22 and Q40/41/42. Check transistor voltages
and diodes for dry solder. It could also be the interstage toroids if RX is poor.

Raj

At 06/09/2020, you wrote:
When i keep my other SSB reciver in the room and talk, i can hear my voice on that receiver. But watt meter show no power. What is the problem? Which part do i need to check?


Evan Hand
 

Nikhil B,
Did you try CW?  That would isolate it to the power amp if no power in that mode.

Here is a PDF with static dc voltages for the uBITX.

NOTE: You do need to press the PTT to go into TX mode to take the TX voltages.  Be sure to have a dummy load or tuned antenna when doing those tests.

73
Evan
AC9TU


Nikhil B
 

Rx seems ok. Some stations come strong. Some weak. Antenna is EFHW in sloper configuration. Dont know how sensitive is the ubitx reciver. But i can definitely hear the strong stations clearly some 5/9 to 5/9+. 


Nikhil B
 

As mentioned in original post, CW works fine gives 5w out on 40m.
Yes i am aware of static voltages. I will try to measure them without blowing anything.😀😀


_Dave_ AD0B
 

The Electret mic element s by far the most common item to fail. It is a very inexpensive part and worth having several on hand..Perhaps there is a spike when you plug them in or unplug them. 

The second most common is from someone modifying the circuit. including, changing the firmware
--
73
Dave
ADOB
Raduino bracket and Ham_Made_Keys


Nikhil B
 

Mic element, as mentioned in original post, is ok. No circuit modification done. I reflashed the firmware, did not solve the issue. It is hardware related, somwhere in SSB chain.


Nikhil B
 

Update.
The issue has been resolved. I gave it to other Ham. He did not find anything wrong he made modifications as in V5 and its working again.