I am hoping that someone could help me out and provide me with a link on where I can purchase a Baofeng microphone. I'm referring to the one that comes with the uBITX, the hand microphone that looks like it is for an HT but it has just the one pin instead of 2 pins.?
Thank you
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'72

The sBitx appears to be using the same improved inductors that the QDX switched to after early problems. ?But I’m still seeing some bleed around. ? It looks like Ashhar is providing about six times the bias current for the 1N4007’s. ? We are running about 2 to 5 times the power output, but the current wouldn’t be increased but by the square root of that amount. ? And where I’m seeing the problem is on the higher bands —not the lower freq bands where you would think the charge carriers would be hard-pressed to stick around long enough. ? ? Not sure if carefully selecting the diode’s or running 2 in parallel would make an improvement?

gordon

I noticed that the stock firmware uses both the standard (double) and float FFTW3 libraries. The install instructions have you build both library versions. It looks like the float libraries are only used in fft_filter.c, the standard libraries are used elsewhere. Is there a reason that fft_filter.c doesn't use the standard library?

FWIW, I modifed the code to use the standard library in fft_filter and build the program with just the standard library and everything seemed to work.

Then, I changed all the code to use just the float library. It seems to work also and at least on receive (I haven't tried transmit), it seems to sound fine. Does the program need the precision of the standard library? Does using the float library speed up the FFT process?
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73,
Mark, N8ME

Thanks.

You mentioned you maintain a fork of WiriingPi. I've heard that the reason Raspberry Pi dropped it from their repo's was because the original developer stopped work on the project. Do you know if the RPi people are coming out with an official way to manipulate GPIO pins from software? It seems odd that that feature is missing from the official operating systems.
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73,
Mark, N8ME

P.S. The frequency didn't change on the sBitx.
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73,
Mark, N8ME

Thanks for the reply.? I typed "f 7050" into the telnet client and the screenshot shows what I got.


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73,
Mark, N8ME

?

In the light of what Evan pointed out about the inductors series resonances in another project, consider the trace below. ? This is the transfer function from the input of the switched low pass filter system all the way to the antenna, when no particular band is enabled. ?

at the time I was making the measurements this didn’t make any sense to me. But now you can see that it clearly shows that there are paths AROUND the filters, and sometimes they are as passable as -25db or so!!! ?This trace should be 2 MHz to 52 MHz so that big spike is somewhere in the low 30 MHz range. ??

That would appear to be a huge problem for the purity of the output signal, right? ?You want the bleed around to be way less than -45 DB.?

if the inductors have series resonances, and the filtering isn’t perfect on powerlines, then signal can get right across. ?Escaping the filters and creating havoc on the output.?

this is another possible improvement
gordon Kx4z?

Looking in the source code file remote.c, I see that sBitx supports a telnet server on port 8081. Using the telnet client built into Windows 10, I can connect to the server about 1 time in 3. When it doesn't connect I get a message 'unable to connect'. When I do connect, the screen clears and prints "sbitx v2.0" at the top. But what can I do at that point. If I type an 'f' I get the response shown in the screen shot.
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73,
Mark, N8ME

开云体育

Evan, I’m also noticing those inductors!!?

sBITX V2 TX problems
Have received a new sBitx V2.
RX is OK! TX no output, no matter in which mode.
PTT switches correctly!
Hardware is OK, works with software V1 without problems.
Faulty settings?
Please help
vy73 DL8DH (Hajo)

Gordon,

The early QDX kit builders (I was one) had to rework the first released boards of the QDX to remove four SMD 47uH chokes and replace them with through-hole inductors.? The reason given was that the chokes' self-resonance changed the filter characteristics.? Could that be the issue here as well?

The equivalent inductors to replace would be L202, L4, L5, L3, and L2.??

Ashhar Farhan stated that the LPF PIN diode switch design was based on Hans Summers' work.? Hans is the designer of the QDX.

I do not own a V2, so I can not verify your tests.? As stated before, the DE I have meets all FCC requirements as far as I can test.? The DE uses relays to switch the LPFs.? This would support your theory that there is an issue with the filter selection circuits.

73
Evan
AC9TU

1.? This thread has been running since Oct 6, now 15 days.? ?Many, many sets of data have been presented, including photos of the measurement setup.? ?There were initial unforced errors due to a DIODE in the Heathkit Cantenna system that added its own spurious responses.? ? The setup has been validated by (a) measurement of an Icom 718 commercial transceiver and (b) measurement of an externally filtered SN#141 sBitx V2 that demonstrated CLEAN output.
2.? ?Despite running for over 2 weeks, not a single other serial number of a production unit has been documented.? ?Perhaps I'm wrong, but I believe the ONLY production unit delivered to a customer whose output has been checked for compliance with spurious response regulations in the United States, is unit #141 -- and it is failing on some bands.? ?
3.? ?A licensed radio amateurs we are compelled to operate kits and other homebrew equipment (after some date) that comply with the spectral purity requirements.? ?The ARRL takes this very seriously and has initiated a Clean Signals Initiative

Web Page:? ?

QST article:? ?

to advance the purity of amateur transitters, specifically noting the problem with LDMOS and MOSFET amplifiers.? ??

4.? The sBitxV2 low pass filters look great in my estimation, yet the signals that I'm recording afterwards don't always bear that same excellence.? ? No one has published any spectrum of a customer-received unit otherwise.? ??

5.? I've now shown that at least ONE diode in the post-filter system appears to be generating (on one band) spurious responses (harmonics) that are above spec.? ??

6.? It appears to me that the next logical step is to isolate the amplifier output, and connect it DIRECTLY to one of the low pass filters,and then DIRECTLY to a dummy load and attenuator system for monitoring with a spectrum analyzer so that all of the associated diode switching, control circuitry, DC voltage generation circuitry, and SWR measurement can be put aside temporarily.? ? I would EXPECT that the result will generally be a "clean signal".? ?The resulting test schematic might look like this:




7.? ?If we can't fix this -- or demonstrate that these measurements have had an ERROR, or that the unit is damaged or not representative of the vast majority of manufactured units -- then I doubt we will ever get the ARRL to publish a complimentary review and this is such a fine effort that it deserves to get acclimation and approval from the ARRL.? ?Ashhar has put a HUGE amount of work into this, and deserves to get credit for his work.? ?The rest of us can pitch in to prove the outcome one way or the other.? ? ?I'm now out of town for a week and hope to get back and eventually take the next step.? ? I've learned a LOT in this process and corrected some of my measurement errors.? ?Perhaps there are others to correct?? ?Haven't seen any contradictory examples however, and able to clearly show CLEAN transmissions in at least two other instances.... so I think this needs further investigation and correction.

73
Gordon KX4Z

I’m trying to understand the receive filtering in sBitx. I’ve been studying and experimenting with Ashar’s well commented code in the function rx_process in sBitx.c. As I understand it, the incoming data along with the overlap data has undergoes a forward FFT to the frequency domain where it is multiplied by the filter coefficients. It then undergoes a reverse FFT to the time domain. However, in the time domain data the filtered audio is now in the imaginary part of the data. Why isn’t it in the real part?
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73,
Mark, N8ME

This site’s data graph suggests that some of these diodes could work in our application. Do we just have some bad ringers?

Look at the dates on the posts.? Those are very old links that are no longer valid.

73
Evan
AC9TU

I think Carl was referring to a separate (breakout) forum just for the sBitx, not an actual breakout board.

Here's a screen recording showing this.

On Wed, Jun 16, 2004 at 03:27 AM, Ashhar Farhan <farhan@...> wrote:

.

This is what your link resolves to: https://www.phonestack.com/laptop-cho-dan-van-phong/