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Audio mixer and dynamic microphone on ubitx #ubitx #ssb


Mark Schraven <mark.schraven@...>
 

Hi there.

First off : please don't start a "Hifi @ssb" discussion, this is not my Intention.

I am using a Behringer Q802USB audio mixer and a Behringer C1 dynamic microphone and went for the mixer because it wasn't much more expensive than the USB Soundcard needed for digimodes.

Now i'm looking to find a way to properly connect it to the ubitx. Without modification i am sure to overdrive the mic-amp and i dont want to cause distortion or IMD.

The mixer output  is 120Ohm +22dB max gain. Digimode works fine ( gain low ), mic sounds distorted even on the phones out as soon as the mixer is connected to the rig, using a 1:1 600Ohm Isolation transformer.

So - do i need to bypass the internal mic preamp to get some kind of "line in" and/or do i need  additional audio attenuation ?

   


 

First put an isolation cap between the mic brown wire and your mixer. Drop the mixer
output to give 15-25mV RMS via a preset or resistive dividers. Rest you can control from the mixer.

Raj

At 03-01-19, you wrote:

Hi there.

First off : please don't start a "Hifi @ssb" discussion, this is not my Intention.

I am using a Behringer Q802USB audio mixer and a Behringer C1 dynamic microphone and went for the mixer because it wasn't much more expensive than the USB Soundcard needed for digimodes.

Now i'm looking to find a way to properly connect it to the ubitx. Without modification i am sure to overdrive the mic-amp and i dont want to cause distortion or IMD.

The mixer output is 120Ohm +22dB max gain. Digimode works fine ( gain low ), mic sounds distorted even on the phones out as soon as the mixer is connected to the rig, using a 1:1 600Ohm Isolation transformer.

So - do i need to bypass the internal mic preamp to get some kind of "line in" and/or do i need additional audio attenuation ?


Mark Schraven <mark.schraven@...>
 

Hi Raj. 

Mic Input is blue(tip) and purple(tip).
What is the input impedance on the ubitx mic input ?

R60 for mic-bias has been removed.

 


 

Sorry Mark, I had the Bitx40 in mind. Yes Blue is ground and purple is input.

Take the input at about 1 - 2.2K thats common. I am not sure what the supplied one is.

Try a 10K preset/pot in series with mic line and see if that works to get 10W@ 40M,
keep that power as the limit.

Raj

At 03-01-19, you wrote:

Hi Raj.

Mic Input is blue(tip) and purple(tip).
What is the input impedance on the ubitx mic input ?

R60 for mic-bias has been removed.