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Baofang Microphone defective

Jeff Debes
 

It seems that my Baofeng mic in my V6 kit was defective or maybe I inadvertently damaged it?
It worked for a time, but then I received reports of bad audio. I monitored my own transmit signal and sure enough, it was distorted sounding. I was surprised that anyone could make out anything that I said.

I just tried a KX3 mic and that works very well.
Has anyone had quality difficulties with the kit mics?
I guess I’m concerned or suspicious that I damaged the stock mic somehow.

Jeff



--
*jeff.debes@...*

Evan Hand
 

Jeff,
You may have damaged the mic, however there have been a large number of issues reported on this board about v6 Baofeng mic issues, so it is just as likely that your mic failed due to a defect.  The one possibility that has not been investigated is the susceptibility of the Baofeng mic to overvoltages.  If you are running the ubitx over 12 volts (most seems to run theirs at 13.8 volts - a common ham power supply), then that may be more than the electret element can handle.  It might be a good reason to install the one or two diodes in series to drop the voltage to the mainboard power, leaving the PA at the 13.8 volts.  This would probably require some surgery on the ubitx board.  The older versions had separate wires for mainboard and PA power.  I did this on my v4 and v5 ubitx to reduce power dissipation on the 5 volt regulator.  For the v6 you would need to add the diodes in line with the power to the board, as there is no longer a separation.  Be sure to select devices that can handle the 2.5 amps or more.

If you do replace the electret element, be sure to select one that can take 14 volts or higher (especially if you are going to run it off of a car system).

I am just reporting my observations, not making a recommendation.  It should be noted that the Baofeng 2m handhelds use 7.4 volt batteries. 
73
Evan
AC9TU

Bill Cromwell
 

I worked on a V6 for another ham and I was not impressed with the mic. I was going to change element but when I went in to unsolder it I found it already not soldered! That is as bad as my early experiences with MFJ stuff. I still don't own any.

good luck and...

73,

Bill KU8H

bark less - wag more

On 6/4/20 11:17 AM, Jeff Debes wrote:
It seems that my Baofeng mic in my V6 kit was defective or maybe I inadvertently damaged it?
It worked for a time, but then I received reports of bad audio. I monitored my own transmit signal and sure enough, it was distorted sounding. I was surprised that anyone could make out anything that I said.
I just tried a KX3 mic and that works very well.
Has anyone had quality difficulties with the kit mics?
I guess I’m concerned or suspicious that I damaged the stock mic somehow.
Jeff

Arv Evans
 

Jeff

Many Baofeng microphones have been found to be defective according 
to earlier posts on this group.  Seems that the defects come in two flavors:
1) the microphone cartridge is not lined up with the hole for audio.
2) the audio hole is not large enough for adequate audio level output.
Some have replaced the Baofeng microphone element with the larger 
one that is shipped with earlier uBITX kits, and enlarged the audio hole 
in the Baofeng case.  This seems to work quite well.

There is another possible cause of rough or distorted audio.  That is the 
use of an overly aggressive microphone amplifier.  If the modulator is 
being over-driven the audio may be clipped on voice peaks.  If the RF PA 
stage is being over driven it can cause distortion of the RF waveform (along
with spurious emission).  

Hope that helps.

Arv
_._


On Thu, Jun 4, 2020 at 9:17 AM Jeff Debes <jeff.debes@...> wrote:
It seems that my Baofeng mic in my V6 kit was defective or maybe I inadvertently damaged it?
It worked for  a time, but  then I received reports of bad audio. I monitored my own transmit signal and sure enough, it was distorted sounding. I was surprised that  anyone could make out anything that I said.

I just tried a KX3 mic and that works very well.
Has anyone had quality difficulties with the kit mics?
I guess I’m concerned or suspicious that I damaged the stock  mic somehow.

Jeff



--
*jeff.debes@...*



Evan Hand
 

Arv,

Good summary.  The one thing I would add is that RF feedback has also been an issue with poor sounding audio.  This has been solved with snap-on ferrites and bypass capacitors if that turns out to be the problem.

73
Evan
AC9TU

Evan Hand
 

Jeff,
I answered your original question, but should have also asked one back:  What if anything changed from when it was working to now when it is not?  By my adding the point to Arv's list reminded me that I had a similar issue when I went from a 20-meter dipole to an off-center feed 40-meter dipole.  The RF feedback on the coax got back into the mic audio.

Just another thing to check out.
73
Evan
AC9TU

MVS Sarma
 

Evan and ARV,
GOOD THOUGHT whether 13.8 etc is damaging the element. Onevpssible solution is to use a small 78L09 in the main board and then use 4.7k or q0k series resistor for feeding on to mic jack.

Secondly, I ssuppose that, the sound carrying hole one mic is deliberately made indirect to prevent water  coffee, beer etc not to directly enter the mic capsule, LoL. 

Reg RF , there is a 1nF across the mic element inside baofeng mic pcb. 

Farhan has provided a 1nF just before reaching mic amp to byepass the ppssibly indiced RF. 

However use of ferrite clip on is a good practice. 

A good topic for discussion. Thanks

Sarma vu3zmv

On Thu, 4 Jun 2020, 11:59 pm Evan Hand, <elhandjr@...> wrote:
Arv,

Good summary.  The one thing I would add is that RF feedback has also been an issue with poor sounding audio.  This has been solved with snap-on ferrites and bypass capacitors if that turns out to be the problem.

73
Evan
AC9TU

Arv Evans
 

Evan

Yes.  In early BITX20 designs we had several instances of RF getting into the 
microphone input.  Problem finally was traced to the use of a coiled-cord (inductance) 
on the microphone. A 0.001 mfd across the electret element in the microphone 
cured all but the most stubborn cases.  Adding a 0.01 across the mike jack 
terminals cured the remainder.  Remember that the PTT lead may also need 
a bypass capacitor.

Arv
_._

On Thu, Jun 4, 2020 at 12:29 PM Evan Hand <elhandjr@...> wrote:
Arv,

Good summary.  The one thing I would add is that RF feedback has also been an issue with poor sounding audio.  This has been solved with snap-on ferrites and bypass capacitors if that turns out to be the problem.

73
Evan
AC9TU

Jeff Debes
 

Excellent! Wow! thanks everyone for the ideas!
I’ll start my investigations!
What was amazing to me was that after listening to my own signal and hearing how distorted the audio was , that stations on ECARS net had even able to discern my callsign. They accurately reported “ Jeff, something is really wrong with your audio”
Thanks again for the various ideas, possible causes, possible solutions, prevention!
BTW it was working well for a while. Maybe it was an over voltage  damage.  I’ll check my lithium ion battery pack voltage.

AC2JB  Jeff
--
jeff.debes@...

Gordon Gibby
 

if you run the bias on some audio stage (either the mic, which has an amplifier in it) or the input stage (by lacking a coupling capacitor)  -- into a non-linear portion of its curve -- then you 'll get terrific distortion.    

That can be done with incorrect circuit connection, failed component, OR with RF interference being  rectified and creating its own bias -- this happened to me reliably with my ICOM-725 when feeding in signals on the rear panel.  HORRIBLE distortion with a commercially produced radio!

Gordon


On Fri, Jun 5, 2020 at 8:53 AM Jeff Debes <jeff.debes@...> wrote:
Excellent! Wow! thanks everyone for the ideas!
I’ll start my investigations!
What was amazing to me was that after listening to my own signal and hearing how distorted the audio was , that stations on ECARS net had even able to discern my callsign. They accurately reported “ Jeff, something is really wrong with your audio”
Thanks again for the various ideas, possible causes, possible solutions, prevention!
BTW it was working well for a while. Maybe it was an over voltage  damage.  I’ll check my lithium ion battery pack voltage.

AC2JB  Jeff
--
jeff.debes@...

Rene
 

I think that i have the same problem, after changing the wire from mike to radio, sound was better ... however still many problems i have to solve..after homeimprovement time enough after summer