Topics

Mics, speech processor? #ubitx

John AE5X <ae5x@...>
 

Morning all,

I'm curious what mics people are using with their uBITX rigs (the included one or something else) and whether anyone has found outboard speech processors to be beneficial?

Here is a schematic for one I'm considering:
http://www.rason.org/Projects/speech/speech.htm

ON7HC
 

Hi John,

I'm using this Ebay item : 253088080650  ($2.27).
It is not really a compressor but rather an automatic gain MIC amplifier. It is very sensitive and your sound quality remains clear. You don't have to shout in the microphone to generate some output ... :)
In my Bitx40 it replaces the original MIC amplifier. The AGC function prevents overloading of the TX chain, so your power remains clean and within the limits.
I'm curious wether a real compressor circuit would still be a better solution for this kind of radio.

Herman - ON7HC

Arvo W0VRA
 

A couple of people are looking at an Analog Devices SSM2167 chip on a board.

https://groups.io/g/BITX20/topic/6468223

I'm waiting for mine to come in.

Michael Hagen
 

Here is my mic with a speech processor in it.  I used the Mic and Sw supplied with BitX.

The PCB is tiny and fits up in the mic tube.  All parts were 3d Printed.

I have only tested it on the scope, the pot can adjust the output all the way to zero.

Testing showed constant output with 1-10mv signal from a generator.

I have provided a schematic.  It is basically made from an AP Note on the IC.

I also have a PCB in BitX that senses the PTT switch on the mic and activates Transmit.

This saves a wire to the Mic, and I can use standard 3.5 mm Stereo cord.   A 6 ft. double ended male was

0.99 at the 99 Cent store,  I cut it in half, making 2 cables.

73's

Mike, WA6ISP


On 1/3/2018 7:39 AM, Arvo KD9HLC via Groups.Io wrote:
A couple of people are looking at an Analog Devices SSM2167 chip on a board.

https://groups.io/g/BITX20/topic/6468223

I'm waiting for mine to come in.

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

Michael Monteith
 

Arvo,
 Keep us posted.  Mine is in shipping too.  Unless the weather changes it might be a while before I could test mine.  My shop is in the garage which is barely above freezing at this point and might be by now. I do think it has potential.  Anxious to see now.

Thanks
73, Michael
KM4OLT

David Arthur
 

I have this module from Adafruit https://www.adafruit.com/product/1713. I don't have a quantitative way to measure how effective it is, but when I hook it up to headphones or my computer line-in the fidelity and gain is _excellent_. You really have to give a loud shout to encounter any clipping. Downside is it will absolutely pick up background noise if you're keyed and not talking :). For now I have it powered by 3 AAA batteries, the plan is to use a 3.3V regulator off the 12V bitx line to power it. 

Still need to figure out a case for it though...

On Wed, Jan 3, 2018 at 12:17 PM Michael Monteith via Groups.Io <michael_r_monteith=yahoo.com@groups.io> wrote:
Arvo,
 Keep us posted.  Mine is in shipping too.  Unless the weather changes it might be a while before I could test mine.  My shop is in the garage which is barely above freezing at this point and might be by now. I do think it has potential.  Anxious to see now.

Thanks
73, Michael
KM4OLT


--
David K4DBZ
Unofficial bitx chatroom: https://discord.gg/CrHvWFc

MAc B
 

Adafruit and aliexpress module are the same, based on MAXIM max9814 chip.

It,s guite good compressor, for our needs is as good as AD's SSM2165/2167

And it is icredibly cheap.

MAc

ON7HC
 

David,

Indeed, the same great working chip MAX9814 (and PCB) like in my previous post #38230.  On Ebay $ 2.27  :) :)
Hard to overload TX, because it's limited. You can select (wired) between 40, 50, 60dB gain.

Herman

Arvo W0VRA
 

On Wed, Jan 3, 2018 at 09:30 am, David Arthur wrote:
Downside is it will absolutely pick up background noise if you're keyed and not talking :). For now I have it powered by 3 AAA batteries, the plan is to use a 3.3V regulator off the 12V bitx line to power it. 
The Analog Devices module has a noise gate to help with that.  On the other hand, I spent a small fortune on it!

I'll borrow 5V from the Raduino to power it.

It'll be in the case with the rest of the radio.

Jeff
 

I added a speech processor to my Bitx some time ago and found that it made a huge difference. I no longer had to talk loudly into the mic and it added enough compression to make the output more constant and I had more control over the audio. I used the SSM2167 and a diagram I found on another website. The schematic can be found here and pictures and a description can be found here.

Dave Bottom <ars.kd6az@...>
 

The eBay adafruit Electret Mic AGC amplifier looks like it would drive the Balance Modulator directly with 2V PTP output. 

Mounted at the Mic connector and a output Gain pot (remove MIC BIAS at the uBITX Mic input or put in a decoupling cap).
This really might work fine.  I'm going to try it.

BTW - I build Boom-Mic headsets for QRP radios, something we added to our radiosport headset line-up a few months ago. Stereo headset, Electret Mic and InLine PTT Using one of our really good aviation noise cancelling Electret Mics.  It has about identical output to the supplied Electret Mic.  The RS50SL headset is stereo (for use originally with the Elecraft KX2, KX3 rigs as well as the ELAD FDM Duo, and Yaesu FT-817) all of which either have dual receive (SDRs) or wired for stereo headset. 

I'm going to build a simplified adapter for our RS55SL SmartPhone/Tablet/Notebook PC headset (runs my Flex remote with an iPad Mini) to do the same for rigs like this one, and will have an InLine PTT.   I'm using the prototype of that adapter on my uBITX now.

Dave WI6R


On Wed, Jan 3, 2018 at 7:15 AM, ON7HC <herman.docx@...> wrote:
Hi John,

I'm using this Ebay item : 253088080650  ($2.27).
It is not really a compressor but rather an automatic gain MIC amplifier. It is very sensitive and your sound quality remains clear. You don't have to shout in the microphone to generate some output ... :)
In my Bitx40 it replaces the original MIC amplifier. The AGC function prevents overloading of the TX chain, so your power remains clean and within the limits.
I'm curious wether a real compressor circuit would still be a better solution for this kind of radio.

Herman - ON7HC




--
73 Dave WI6R

ON7HC
 

Hi Dave,

Driving directly the Balance Modulator :
I can confirm that this works very good. I'm working already more than 2 months without the original MIC amplifier.
Works like a charm ...

73
Herman

Kelly Jack
 

Jeff,

Keen to understand more about your processor circuit.

Do have the pots for R7 (compression) and R8 (output)?  Also is R9 a short?
Where is it powered from? the standard bitx40 circuit takes its power from the same place that the signal is input to the mic preamp. Is this what you did?

Regards


Simon


VK3ELH

Arvo W0VRA
 

The next thing would be to add some EQ, at least a 100 Hz HPF in front of the compressor.

Arvo W0VRA
 

And then there's this, which might be overkill...

http://homepages.ihug.com.au/~daz2002/tech/DSP2/index.html

Michael Monteith
 

Jeff,
 Good to hear. I have mine on the slow boat from China.  I'm glad it worked as I suspected it would. 

Thanks again for sharing.
73, Michael KM4OLT

frederick.brown@...
 

I have built an audio compressor for an Adafruit mic module to use with my uBitx. I was wondering what drive voltage will work well with the modulator. I was also wondering what is the input impedance of the modulator.

Regards,

fred brown