One possibility for CW transmit would be to inject a low level keyed 45mhz square wave at CLK1,
the 45mhz crystal filter will turn that into a sine wave.
CLK2 can remain a square wave at Transmit_Freq + 45mhz, same as during SSB transmit,
the D1,D2 mixer will generate a sine wave for the power amp at the Transmit_Freq.
Along with a bunch of other mixer products and crap coupled from power amp into the IF amp, as usual.
Allisons extra filters would fix that, at the cost of considerable complication.
But the above simple CLK1 scheme should be sufficient to reduce harmonics during CW transmit.
Jerry, KE7ER
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Show quoted text
On Mon, Mar 4, 2019 at 09:10 AM, Jerry Gaffke wrote:
You have that backwards.
CLK2 goes into the mixer at D1,D2, and is at the CW operating frequency.
CLK0 and CLK1 are dead in the water when transmitting CW.
Class C power amps are how most CW-only transmitters have worked over the last 100 years
Class C creates?a big honking square wave that then needs to be sorted out by effective low pass filters.
The solution for the uBitx is simple enough, make the transmit LPF's work properly.
Unfortunately, the relays are kind of tough for some of us to work on,
and few can be bothered to measure the results.
Jerry, KE7ER
toggle quoted message. . .
?
On Mon, Mar 4, 2019 at 08:49 AM, Jim Sheldon wrote:
I don't believe that will work as CLK02 is not used for CW transmit. CLK01 produces "ON FREQUENCY OF TRANSMISSION RF (square waves) for CW
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Re: How to connect ubitx microphone jack to soundcard output
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
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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.
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Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
Discussion of the microphone input and related DC isolation has been coming up for discussion
periodically ever since the first BITX design.? Best approach is to look at the schematic and that
of your input device to insure that proper isolation and level adjustment is provided.? Just making
statements about what should and should not be used probably should be backed up with "why it
works this way" explanations.?
This is not to deprecate any of the statements already made, just to suggest that what works for
XYZ rigs may not be the perfect solution for a particular version of BITX.? The BITX microphone
input circuit has changed slightly over the years.?
Arv? K7HKL _._
So things are actually worse when using a transformer to isolate the mic line? So things like the easy-digi etc. make things worse? this was not my experience at all. before using a transformer, i could not sustain the audio connection between my (horrible) single audio jack on my handheld PC, but after i could without issue.
So, it's possible that using easy-digi or a transformer is shunting the voltage on the mic line to ground, which could cause all manner of strange problems with the uBitx? Is this correct?
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Jim,
Clock#2 is used for CW, but the frequency is adjusted to the dial setting +/- the CW tone depending on the CWU/CWL selection. Still, it is a square wave at the HF frequencies, not so at the higher frequencies for the IF mixing.(>45 MHZ). Still not a "good" sine wave, but better than the 7.0 MHz one.
I too would go for the sine wave si5351 replacement. There is the AD9834 that produces a sine wave to 75mhz.? Would need to add it to the i2C line and replace the si5351 clock#2 with this device. also need to adjust the Raduino program, and now calibrate two different devices.
Might be worth looking into.
73
Evan
AC9TU
73
Evan
AC9TU
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You have that backwards.
CLK2 goes into the mixer at D1,D2, and is at the CW operating frequency.
CLK0 and CLK1 are dead in the water when transmitting CW.
Class C power amps are how most CW-only transmitters have worked over the last 100 years
Class C creates?a big honking square wave that then needs to be sorted out by effective low pass filters.
The solution for the uBitx is simple enough, make the transmit LPF's work properly.
Unfortunately, the relays are kind of tough for some of us to work on,
and few can be bothered to measure the results.
Jerry, KE7ER
toggle quoted message
Show quoted text
On Mon, Mar 4, 2019 at 08:49 AM, Jim Sheldon wrote:
I don't believe that will work as CLK02 is not used for CW transmit. CLK01 produces "ON FREQUENCY OF TRANSMISSION RF (square waves) for CW
|
Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
So things are actually worse when using a transformer to isolate the mic line? So things like the easy-digi etc. make things worse? this was not my experience at all. before using a transformer, i could not sustain the audio connection between my (horrible) single audio jack on my handheld PC, but after i could without issue.
So, it's possible that using easy-digi or a transformer is shunting the voltage on the mic line to ground, which could cause all manner of strange problems with the uBitx? Is this correct?
|
I don't believe that will work as CLK02 is not used for CW transmit. CLK01 produces "ON FREQUENCY OF TRANSMISSION RF (square waves) for CW and that is where the harmonics need to be surpressed. There is no way to successfully convert CLK01 to even a pseudo sine wave over the complete 1.8-30 MHz frequency range for clean CW transmission. ??
Now, IF Silicon Labs were to produce a chip that was a pin-for-pin replacement for the Si5351a but output a sine wave instead, then I'd instantly swap out the 5351's on all my uBITX Raduino's and the TSW Raduino Clone and BITeensio cards. ?Until that happens the multiple LPF's with extra switching is about the only fix IMO.
Jim - W0EB
------ Original Message ------
Sent: 3/4/2019 10:13:33 AM
Subject: Re: [BITX20] Pseudo-Sine?
Since someone asked about an RC filter ...Logical place would be on Clk02 (45-75 Mhz)? ...as an example random/scraped from google
Double the l's and spice it ...Not simple ..There is a reason RF design engineers get paid the big bux, right?
Jim
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Hello guys,
VU3EDU Subhash from india here.
I was wanting to mod my bitx40 to add a touchscreen display like nextion to it just like on the ubitx.
I did a lot of research on it, but only was able to find a sketch by PD8W. Please help out in this manner as I am? still a rookie to amateur radio.
Regards
VU3EDU
Subhash Herur
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Re: How to connect ubitx microphone jack to soundcard output
I just ?wired up and tried a $5 audio amp from ebay ,works a dream. Cheers Ross?
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Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
Gordon, I’ve been using the easydigi’s, is that the purpose of cap in between both mic and audio connections to radio?
toggle quoted message
Show quoted text
On Mar 4, 2019, at 10:51 AM, Gordon Gibby < ggibby@...> wrote:
Transformer Makes it worse. ?
Do not short the dc bias voltage—likely it will take input transistor or op amp to un-usable ?bias?
On Mar 4, 2019, at 17:27, Joe Puma < kd2nfc@...> wrote:
could something like a 600:600 transformer solve that issue too? I’ve ?been putting them between all my audio and mic I/O’s when connecting to pc/soundcard
Joe
kd2nfc
On Mar 4, 2019, at 10:24 AM, Gordon Gibby < ggibby@...> wrote:
We made the mistake of not dc blocking mic inputs of some commercial vhf rigs —-bad distortion in input stage?
On Mar 4, 2019, at 16:41, Praba Karan < vu3dxr@...> wrote:
Is dc blocking capacitor necessary between sound card audio output and mic input of ubitx during digital modes?. I made a direct connection between above without DC blocking cap. Though? my ubitx received so many, very few logged my
cq calls as per pskreporter. Any advices?
|
Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
Agreed that the supplied voltage on the mic capsule will give you hassels. With a 600:600 transformer things will be worse. The supplied voltage will now go through the transfomer winding to ground. Only solution is to stop this voltage completely. Via a switch. Using the mic, switch it on. Use digi, switch it off.
|
Since someone asked about an RC filter ...Logical place would be on Clk02 (45-75 Mhz)? ...as an example random/scraped from google
Double the l's and spice it ...Not simple ..There is a reason RF design engineers get paid the big bux, right?
Jim
|
Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
...more on this here: /g/BITX20/message/65994
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Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
There is a voltage on the MIC circuit, you NEED a 1:1 transformer and/or a blocking cap, or your laptop/tablet/soundcard will freak out at the least, or get damaged at the worst.
The MIC in on my V4 uBitx needs quite a high level, so LINE OUT on a computer (etc.) is well suited to it without the need for attenuation, but there is no way it will work correctly without something to do away with the voltage on the line, especially if the sound device is auto-sensing.
|
Re: How to connect ubitx microphone jack to soundcard output
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.
|
Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
Transformer Makes it worse. ?
Do not short the dc bias voltage—likely it will take input transistor or op amp to un-usable ?bias?
On Mar 4, 2019, at 17:27, Joe Puma < kd2nfc@...> wrote:
toggle quoted message
Show quoted text
could something like a 600:600 transformer solve that issue too? I’ve ?been putting them between all my audio and mic I/O’s when connecting to pc/soundcard
Joe
kd2nfc
On Mar 4, 2019, at 10:24 AM, Gordon Gibby < ggibby@...> wrote:
We made the mistake of not dc blocking mic inputs of some commercial vhf rigs —-bad distortion in input stage?
On Mar 4, 2019, at 16:41, Praba Karan < vu3dxr@...> wrote:
Is dc blocking capacitor necessary between sound card audio output and mic input of ubitx during digital modes?. I made a direct connection between above without DC blocking cap. Though? my ubitx received so many, very few logged my
cq calls as per pskreporter. Any advices?
|
Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
could something like a 600:600 transformer solve that issue too? I’ve ?been putting them between all my audio and mic I/O’s when connecting to pc/soundcard
Joe kd2nfc
toggle quoted message
Show quoted text
On Mar 4, 2019, at 10:24 AM, Gordon Gibby < ggibby@...> wrote:
We made the mistake of not dc blocking mic inputs of some commercial vhf rigs —-bad distortion in input stage?
On Mar 4, 2019, at 16:41, Praba Karan < vu3dxr@...> wrote:
Is dc blocking capacitor necessary between sound card audio output and mic input of ubitx during digital modes?. I made a direct connection between above without DC blocking cap. Though? my ubitx received so many, very few logged my cq calls
as per pskreporter. Any advices?
|
Hey Allison, since all we need are a few DB less harmonics, would a modest number of limited stages diode switched accomplish a useable goal? ?Maybe 10-12 dB improvement on a daughterboard??
You probably solve questions like that in your head in seconds ...
Gordon
On Mar 4, 2019, at 16:42, ajparent1/KB1GMX < kb1gmx@...> wrote:
toggle quoted message
Show quoted text
?Is there RC that can do it?
Best answer for that is SERIOUSLY?? ;)
The frequency range is more than 10:1 from about 1.8mhz to 29.9999 pick an rc value that rounds the edges
at say 3mhz that doesn't kill the signal completely at 14mhz?? Seriously there is a lack of understanding about
RC fitlers.? ?Hint, a value that would have useful effect will also absorb about half the signal, double the frequency
the absorption greatly increases. so many switched RC filters with loss.? So much for the wishful the magic pill.
The only choice is a LC filter as then the band pass or in the case of low pass can be high enough to pass the
signal mostly unmolested and still suppress its harmonics.? Works well save for you need like 5-7 switched
filters to do it.? Since filtering seems to be a bad word, there are few solutions that do not involve a greater
amount of hardware.?
Allison
|
Re: DC blocking cap between souncard and ubitc mic input.
#ft8
#ubitx
We made the mistake of not dc blocking mic inputs of some commercial vhf rigs —-bad distortion in input stage?
On Mar 4, 2019, at 16:41, Praba Karan < vu3dxr@...> wrote:
toggle quoted message
Show quoted text
Is dc blocking capacitor necessary between sound card audio output and mic input of ubitx during digital modes?. I made a direct connection between above without DC blocking cap. Though? my ubitx received so many, very few logged my cq calls
as per pskreporter. Any advices?
|
?Is there RC that can do it?
Best answer for that is SERIOUSLY?? ;)
The frequency range is more than 10:1 from about 1.8mhz to 29.9999 pick an rc value that rounds the edges
at say 3mhz that doesn't kill the signal completely at 14mhz?? Seriously there is a lack of understanding about
RC fitlers.? ?Hint, a value that would have useful effect will also absorb about half the signal, double the frequency
the absorption greatly increases. so many switched RC filters with loss.? So much for the wishful the magic pill.
The only choice is a LC filter as then the band pass or in the case of low pass can be high enough to pass the
signal mostly unmolested and still suppress its harmonics.? Works well save for you need like 5-7 switched
filters to do it.? Since filtering seems to be a bad word, there are few solutions that do not involve a greater
amount of hardware.?
Allison
|
Jim Sheldon
Kobus ZS6CHK
