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:

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

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

/g/BITX20/topic/6468223

I'm waiting for mine to come in.

开云体育

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

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

/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@...

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

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

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

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.

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 and pictures and a description can be found .

--

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

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

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

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

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

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