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How to connect ubitx microphone jack to soundcard output

 

Hello and sorry to ask a question that has no doubt be answered many times.? I would like to connect to the ubitx microphone jack to an USB soundcard speaker output.? So far, I get nothing but garbled audio when attempting to transmit.
I've simply used a 3.5 mm stereo patch cord from the ubitx microphone jack to the soundcard speaker output.? I suspect the circuit for the electret microphone element won't allow this.

I can receive, change frequencies, etc. with flrig and fldigi using the same soundcard microphone input and a USB serial port.

Thank you in advance.
Robert McClements
 

You might like to try adding a series dc blocking capacitor.

Something like 100nF or 1uF might do the job, but try what is to hand in your junk box.

If polarised connect +ve leg to uBitx.

73 Bob GM4CID
 

In addition to the capacitor that Robert is suggesting, be sure to try the level adjustment on the PC.? I found that I had to run at very low volume levels when doing my two tone tests using the PC as the tone generator.?

The second thing is to verify the type of jack on the USB sound card:? Is it a TRRS (Tip Ring Ring Sleeve) like stereo headphones with mic, or just the one ring.? The wiring on the TRRS version puts the ground on the ring closest to the sleeve, and the sleeve is the mic input to the PC.? For me I had to get a TRRS plug to get it wired correctly.? Tip and First Ring wired together to the mic input on the uBitx with ground to the second ring of the PC plug and Sleeve on the uBitx.? No connection to the sleeve on the PC side of the cable.

Lastly, you may need to add a level control potentiometer, though I did not.? I would put a DC blocking cap between the uBitx and the level control wiper, do not believe you need one on the output of the sound card.

these are my thoughts, you might want to get some more input before implementing them.

73
Evan
AC9TU
 

I would use psk like interfaces. Of course a block capacitor, an audio 1:1 600ohm transformer, a fixed attenuator plus a volume potentiometer between the ubitx mic input and the output of the sound card. And interface like that may be used for SSB as well, other than digital modes of course. 'Voice Shaper' is a very good free Windows program that would add a 'virtual compressor' to the Ubitx. I had tried Voice Shaper 10 years ago, when I was still using Windows, and I was impressed.


Il 03/mar/2019 19:46, "Evan Hand" <elhandjr@...> ha scritto:
In addition to the capacitor that Robert is suggesting, be sure to try the level adjustment on the PC.? I found that I had to run at very low volume levels when doing my two tone tests using the PC as the tone generator.?

The second thing is to verify the type of jack on the USB sound card:? Is it a TRRS (Tip Ring Ring Sleeve) like stereo headphones with mic, or just the one ring.? The wiring on the TRRS version puts the ground on the ring closest to the sleeve, and the sleeve is the mic input to the PC.? For me I had to get a TRRS plug to get it wired correctly.? Tip and First Ring wired together to the mic input on the uBitx with ground to the second ring of the PC plug and Sleeve on the uBitx.? No connection to the sleeve on the PC side of the cable.

Lastly, you may need to add a level control potentiometer, though I did not.? I would put a DC blocking cap between the uBitx and the level control wiper, do not believe you need one on the output of the sound card.

these are my thoughts, you might want to get some more input before implementing them.

73
Evan
AC9TU

 

Any 600ohm 1:1 audio transformer is a very good idea. 600ohms is a typical impedance presented by headphones these days, so it's a good value to shoot for. There is a voltage present on the MIC in of the uBitx, and this will confuse most modern soundcards and laptops, maybe totally distorting the audio, but If when You plug in a headphone or mic to your computer, the operating system detects this and says something in a dialog box, You need to use AT LEAST a blocking capacitor for the MIC IN on the uBitx/Line out on the computer, but most likely a 1:1 transformer also, otherwise the connection will be very unstable. You will find the computer will switch randomly between the input jack and any built-in mic especially on a laptop, unable to sense if the jack has a load on it correctly.

If You are unlucky enough to have a SINGLE jack for BOTH mic and headphones on Your laptop/tablet - for a headset, you should get one of these

Remember the Audio out using a splitter like this, or a (green) jack on a computer itself for headphones out is also STEREO, and using a mono plug either end of a lead for this will cause problems. So, You might ALSO need one of these which you can then adapt.

Once You get things worked out, You will be very happy with the uBitx for digital - audio using cables, and control via cat (ft817 emulation) with the CEC firmware.
 

I just ?wired up and tried a $5 audio amp from ebay ,works a dream. Cheers Ross?

20190304_235110.jpg

Joe Puma
 

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What’s a good value for the blocking cap? If that’s the purpose of the one on the easydigi, it’s value is .1uf



Joe
KD2NFC?


On Mar 4, 2019, at 10:55 AM, Playthatbeat Mrdj <playthatbeat303@...> wrote:

Any 600ohm 1:1 audio transformer is a very good idea. 600ohms is a typical impedance presented by headphones these days, so it's a good value to shoot for. There is a voltage present on the MIC in of the uBitx, and this will confuse most modern soundcards and laptops, maybe totally distorting the audio, but If when You plug in a headphone or mic to your computer, the operating system detects this and says something in a dialog box, You need to use AT LEAST a blocking capacitor for the MIC IN on the uBitx/Line out on the computer, but most likely a 1:1 transformer also, otherwise the connection will be very unstable. You will find the computer will switch randomly between the input jack and any built-in mic especially on a laptop, unable to sense if the jack has a load on it correctly.

If You are unlucky enough to have a SINGLE jack for BOTH mic and headphones on Your laptop/tablet - for a headset, you should get one of these

Remember the Audio out using a splitter like this, or a (green) jack on a computer itself for headphones out is also STEREO, and using a mono plug either end of a lead for this will cause problems. So, You might ALSO need one of these which you can then adapt.

Once You get things worked out, You will be very happy with the uBitx for digital - audio using cables, and control via cat (ft817 emulation) with the CEC firmware.

 

The highest value capacitance, the better, I would use either a nonpolarized electrolytic or polyester caps for this audio application. Then a 1:1 dc- isolating audio or data transformer to get rid of ground loop issues. Another cap in series on the other end of the cable.


Il 04/mar/2019 18:20, "Joe Puma" <kd2nfc@...> ha scritto:
What’s a good value for the blocking cap? If that’s the purpose of the one on the easydigi, it’s value is .1uf



Joe
KD2NFC?


On Mar 4, 2019, at 10:55 AM, Playthatbeat Mrdj <playthatbeat303@...> wrote:

Any 600ohm 1:1 audio transformer is a very good idea. 600ohms is a typical impedance presented by headphones these days, so it's a good value to shoot for. There is a voltage present on the MIC in of the uBitx, and this will confuse most modern soundcards and laptops, maybe totally distorting the audio, but If when You plug in a headphone or mic to your computer, the operating system detects this and says something in a dialog box, You need to use AT LEAST a blocking capacitor for the MIC IN on the uBitx/Line out on the computer, but most likely a 1:1 transformer also, otherwise the connection will be very unstable. You will find the computer will switch randomly between the input jack and any built-in mic especially on a laptop, unable to sense if the jack has a load on it correctly.

If You are unlucky enough to have a SINGLE jack for BOTH mic and headphones on Your laptop/tablet - for a headset, you should get one of these

Remember the Audio out using a splitter like this, or a (green) jack on a computer itself for headphones out is also STEREO, and using a mono plug either end of a lead for this will cause problems. So, You might ALSO need one of these which you can then adapt.

Once You get things worked out, You will be very happy with the uBitx for digital - audio using cables, and control via cat (ft817 emulation) with the CEC firmware.

 

I suppose that there is a lot of variation in USB sound cards, but I had good luck hooking a USB sound adaptor directly to my UBITX microphone input with a stereo mini jack cable from the headphone output of the sound adaptor. Surprisingly it does not cause the radio to key into the transmit mode with the PTT connected to one of the output channels.

For audio output from the UBITX to the microphone input of the sound adaptor I cut a stereo mini jack cable and hooked the adaptor's microphone input to the ground and high side of the UBITX volume control. The audio from the volume control to sound adaptor microphone input is slightly more than I'd like. I may add a resistive divider to cut the level a bit. I use this arrangement for FT8.

Tom, wb6b
 

FWIW here's my version of the Easy Digi.? I use it with a USB sound card dongle and a serial port for TX control.
Mike
K5ESS

K5ESS Easy Digi.pdf
K5ESS Easy Digi.pdf

Gordon Gibby
 

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Thanks k5ess

Frequency rolloff can be calculated using standard formulas for an RC network. ?Good practice for the radio amateur. ? Depends on the resistance of the input circuit you were driving with that .1 ?F. ?Apparently that has been quite adequate for most people or they still would not be selling so many! ? If your low frequencies are a bit attenuated, add a capacitance in parallel with the .1. ? Good practice for the radio amateur!

Gordon



On Mar 6, 2019, at 07:22, K5ESS via Groups.Io <k5ess.nothdurft@...> wrote:

FWIW here's my version of the Easy Digi.? I use it with a USB sound card dongle and a serial port for TX control.
Mike
K5ESS
<K5ESS Easy Digi.pdf>
 

There is a dc blocking cap in the ubitx circut, c60, you don't need another. I used a pair of audio transformers to isolate the radio signals, one on the mic side and one on the input side to the computer.

Adding in dongle sound card in the ubitx seems to simplify the computer set up.
 

You will have to remove R60 then you don't need another blocking cap. If you don't remove R60 then
you need another cap.

Raj

At 06-03-19, you wrote:
There is a dc blocking cap in the ubitx circut, c60, you don't need another. I used a pair of audio transformers to isolate the radio signals, one on the mic side and one on the input side to the computer.

Adding in dongle sound card in the ubitx seems to simplify the computer set up.
 

Thank you all for the suggestions on how to interface a soundcard with the ubitx.? I ended up using an EasyDigi.? However, in all of the experimenting before getting an EasyDigi, I've managed to destroy something in the radio.? Now I find that when using the microphone and keying it, I have a carrier present. The radio will transmit SSB, but with the unsuppressed carrier along with it.

I can also now transmit PC generated digital modes, but also along with it, the? unsuppresed carrier.? CW is as normal and receive in all modes is unaffected.

SSB worked properly two weeks ago, which was before I started attempting to interface to a PC.? I've destroyed a component I would guess, but have no idea of which one it may be.? Looking at the board, there is nothing obvious.

Any ideas as to what I've broken?

Thanks,

Karl - W5QJ
 

Most of the carrier should be getting suppressed by the balanced modulator.
If the carrier is about as strong as your main signal, look very hard at D5 and T7,
perhaps a broken or shorted transformer wire, possibly a blown diode.
The node from T7 back to C63 and C50 should have zero volts when there is no mike input,
a fraction of a volt of AC audio centered on ground when there is mike input.

If the carrier is mostly suppressed but enough there to be a bit annoying,
then could be you need to get into the menu and move the BFO further away from the filter passband.

Any idea what all you did between when it worked and when it didn't?
Were you messing around with the BFO in the menus?
Applying several volts of audio to the modulator somehow, enough to blow the diodes?
Significant mechanical shock to the rig?
My best guess is a cold solder joint, short, or broken wire at T7.

Jerry, KE7ER


On Fri, Mar 15, 2019 at 06:02 PM, Karl Heimbach wrote:
Thank you all for the suggestions on how to interface a soundcard with the ubitx.? I ended up using an EasyDigi.? However, in all of the experimenting before getting an EasyDigi, I've managed to destroy something in the radio.? Now I find that when using the microphone and keying it, I have a carrier present. The radio will transmit SSB, but with the unsuppressed carrier along with it.

I can also now transmit PC generated digital modes, but also along with it, the? unsuppresed carrier.? CW is as normal and receive in all modes is unaffected.

SSB worked properly two weeks ago, which was before I started attempting to interface to a PC.? I've destroyed a component I would guess, but have no idea of which one it may be.? Looking at the board, there is nothing obvious.

Any ideas as to what I've broken?

Thanks,

Karl - W5QJ
 

Hello Jerry,

Thanks for the reply and suggestions of where to look.?? I would guess it has something to do with me feeding the ubitx microphone input directly from the line output from a C Media soundcard dongle.? I had no isolation transformer or blocking cap in between the two until I installed the EasyDigi.? SSB worked fine ten days ago, but since then, I've continued to attempt to interface the ubitx and soundcard with just a 3.5 mm stereo cable.

I haven't dropped the radio, or touched the calibration of the BFO.? I thought about reloading the configuration I've been happy with, but didn't want to unless absolutely necessary.

I've been using the radio on CW for a year now and SSB infrequently without issue.

Your comment "Applying several volts of audio to the modulator somehow, enough to blow the diodes?" is what I suspect the problem could be.? I would guess the soundcard line output is somewhere around 5V.

Karl, W5QJ

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