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Re: New ubitx CW not transmitting
Hi Curt,
Thank you for your reply. I think I have seen the diagram if you want to use a paddle, then you need to use use different value resistors for the dit and dah respectively.? I'll research that after I get the straight key working. As I mentioned in my original post, going into the ubitx "Settings", specifically "6:Setup>Read ADC" the bottom line shows 1032.? When press the key, it changes to zero.? When I release the key, it goes back to 1032, so the Aurduino is getting the information, so the connections have to be ok - ???? Seems the Aurduino is not sending the information on to the TX relay/logic - ??? PTT and the mic work fine.? TX led changes, and I get motion on the power meter. It's a mystery... Allen KC8VRI |
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Re: New ubitx CW not transmitting
Hi,
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I have a V3 uBitX and now running the CEC software. I don't recall an "ADC" menu item so I don't know what that is for. I did just look through the setup menu on mine and I see "ADC line monitor". I will have to look it up in the manual to see what it's for. I must have blown by it thinking it is for some mod that I have not installed. 73, Bill KU8H On 1/21/19 1:25 PM, howellubeen@... wrote:
Hi Bill, --
bark less - wag more |
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Re: New ubitx CW not transmitting
Hi Bill,
Thanks for your reply. Yes, when I PTT the mic (and talk), the unit goes into TX mode and my external power/water meter moves back & fourth.? When I key down on the straight key, the display, nor the TX led, nor the power meter give any indication of CW being transmitted. With the straight key installed, it stays in RX mode, however, the when I key from the ADC setting, the value changes from 1032 to 0 when I key down, so the Aurduino is getting the key press.? Seems the Aurduino is not sending the key press to the TX circuit - ??? |
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
The discussion here thus far seems appropriate for this bitx20 group.
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If we're running off into the weeds on SA's much further though, might want to move it over to the HBTE group. Jerry On Mon, Jan 21, 2019 at 10:04 AM, Jerry Gaffke wrote:
There has been some discussion lately in? ??/g/HBTE/messages?expanded=1 |
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
Yup, as I had said, filter out the strong signals first.
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With a signal generator, step attenuator, and RTL-SDR/DVB-T dongle plus upconverter, you could figure out the? response of the notch filter at both the carrier and at the harmonic/spur frequencies of interest. The signal generator could an si5351, perhaps filtered to a sine wave though not necessarily. A good spectrum analyzer with tracking generator would be easier and faster, but is not required. As a first cut, I wouldn't bother with the notch filter. Just make sure spurs and harmonics are at least 40 dB down from the carrier. And learn a whole bunch of skills and tricks that will be useful if you ever get a chance to play with a better spectrum analyzer. The SDRplay has a 12 bit ADC, and there are recent attempts at code to make it more of a spectrum analyzer:??? That might be the next logical step up from an RTL-SDR. ? There has been some discussion lately in? ??/g/HBTE/messages?expanded=1 about various approaches to building a spectrum analyzer. I'd like to think something for HF (0-55mhz) with a 100+ dB dynamic range could be kitted up for a third the cost of that RF Explorer. Jerry, KE7ER On Mon, Jan 21, 2019 at 09:25 AM, Bill Cromwell wrote: The work-around I saw was using a notch filter to reduce the carrier a specified or known amount. The idea being the carrier is reduced going into the SA but the harmonics are not. Obviously close-in spurs are attenuated too. So it's not good for measuring those unless they are really gross. Nothing is done to the ADC. |
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Re: New ubitx CW not transmitting
Hi Allen,
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I assume that "SSB is okay" means that you have output when you speak into the mic. Your external watt meter bobs up and down with your speech. Does the display change to show CW on the display when you try to transmit? Do your hear a relay click when you press the key? If no, it is not being put into CW transmit mode. Check the wiring. If yes then you have left something out of your description. Or...check your wiring. 73, Bill KU8H On 1/21/19 11:52 AM, howellubeen@... wrote:
My apologies if this has already been answered.? newbie here.? Just installed a new ubitx (4.3) in the case. Very enjoyable build.? So far, everything seems to work (had to replace their bad speaker), except CW transmitting.? I plug in a straight key or paddle and it does nothing.? I checked the resistor value - it's OK.? I went into setup, and could see the ADC value go from 1023 to 0 when the key is pressed, so it seems the Aurduino is seeing the key. --
bark less - wag more |
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
Hi Jerry,
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The work-around I saw was using a notch filter to reduce the carrier a specified or known amount. The idea being the carrier is reduced going into the SA but the harmonics are not. Obviously close-in spurs are attenuated too. So it's not good for measuring those unless they are really gross. Nothing is done to the ADC. The trick is to assure we reduce the carrier without reducing any other part of the spectrum. A good spectrum analyzer with a tracking generator could do that. It would be needed each time the 'trick' was used and adjusted. We might be able to do that but it seems like more of a headache than it's worth. I would have trouble trusting the notch. 73, Bill KU8H On 1/21/19 11:33 AM, Jerry Gaffke via Groups.Io wrote:
If anybody can remember more about this 40dB dynamic range get around, I'd be very curious. --
bark less - wag more |
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Re: New ubitx CW not transmitting
Allen
I have the same enclosure.? If indeed you have the 4.7k ohm resistor installed (on that board with the connectors that mounts on front panel) -- then it must be a connection issue.? In this configuration the ubitx will do CW with a straight key - but NOT a paddle.? Use of a paddle requires two specific resistor values than are usually mounted external - so that we can reconfigure for straight key.? [ps you have to dig on the web to find instructions for paddle use with the ubitx keyer - KD8CEC I think has a nice page on this] With the ubitx in LSB or USB - it 'configures' for CW transmit whenever it measures an appropriate voltage level on this pin of the arduino.? Then key up it is back to receive.? So unlike most rigs - there is not a specific CW mode.? if everything else is working - I suggest it is a connection issue in this path.? Those accessory boards are easy to get solder bridges on - as I found.? If you have the PTT LED installed - it should go red key down - and the LCD should change to CW (only when key down).? So do carefully check the entire path with a DVM to see what is really connected.? Curt |
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
Hello Jerry and group, The DVB-T dongles are not really intended to be used as I/Q capture devices, as-designed - and so the 40dB dynamic range isn't necessarily an issue, within the receive passband of the unit.? Since they're designed as TV tuners, they have a tuner before the demod (which contains the ADC) that has a tracking filter of sorts - depending upon the tuner architecture, this may be a zero-IF baseband filter, or a SAW filter, etc. In short, the 40dB dynamic range should theoretically only affect the 8MHz-ish span of the tuner's frontend filter - but the frontends aren't always terribly robust on consumer devices, and the filter isn't infinite-stop-band for adjacent frequencies.? For amateur use, this is obviously a huge swath of signals (perhaps even encompassing the second harmonic!), but for the intended use of TV reception you're only looking at the adjacent TV channels down in the skirts of the passband filter. I hope this explanation makes sense - to be honest I'm speaking in broad generalities, because I've never looked closely at how the popular dongles behave.? However, I am rather familiar with how modern TV tuner/demod chipsets behave. As an aside - knowing and understanding the limitations of your test equipment can enhance their useful-ness considerably.? For instance, you might be able to look farther than 40dB down, harmonic-wise, if you can get the fundamental signal outside of the tuner's passband while measuring the harmonic content - but this assumes that the front-end isn't overloading from the fundamental.? This should be able to be determined by varying the input level of the fundamental, and then watching for the harmonic levels to increase/decrease by the same amount (that is, add a 3dB pad and verify that the harmonics decreased by 3dB, and not 6dB as you might see from input overload).? I would suggest using different valued external pads/attenuators, so that all measurements are made with the same internal input attenuation setting on the tuner itself - to try and minimize the error caused by (ab)using a consumer device as test equipment. 73, Josh, KB8NYP On Mon, Jan 21, 2019 at 11:33 AM Jerry Gaffke via Groups.Io <jgaffke=[email protected]> wrote: If anybody can remember more about this 40dB dynamic range get around, I'd be very curious. |
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New ubitx CW not transmitting
My apologies if this has already been answered.? newbie here.? Just installed a new ubitx (4.3) in the? case.? Very enjoyable build.? So far, everything seems to work (had to replace their bad speaker), except CW transmitting.? I plug in a straight key or paddle and it does nothing.? I checked the resistor value - it's OK.? I went into setup, and could see the ADC value go from 1023 to 0 when the key is pressed, so it seems the Aurduino is seeing the key.
PTT SSB transmit works fine, just a dead CW key. Any advice? Thanks, Allen, KC8VRI |
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Re: Good mic for Ubitx and Bitx40
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
If anybody can remember more about this 40dB dynamic range get around, I'd be very curious.
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Can't imagine how you would set up an 8bit ADC to get around the dynamic range problem. Seems the only path is to somehow filter out the strong signal(s). Would be interesting to tear apart an RF Explorer. I'd half expect to find a DVB-T dongle buried in there somewhere. An RTL SDR plus upconverter and step attenuator can be a very useful "toy". Even if it only has a 40dB dynamic range. Verifying that spurs and harmonics from a uBitx are at least 40dB down is about good enough for a 10W rig.? Much better than just hoping. Educational too. Jerry On Mon, Jan 21, 2019 at 08:17 AM, Bill Cromwell wrote:
I read something in an ARRL publication about getting around that 40 dB dynamic range problem. Maybe by W7ZOI or W1FB. But it almost wants a spectrum analyzer to set it up. So it's a circular solution. Circular means chasing your own tail :) If you have a spectrum analyzer to set it up why do you need the toy analyzer? |
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
I am fine with keeping it public, just did not want to to go too far off topic or create unwanted churn.
Disadvantage of starting another topic is that it will not get to people that need the information due to the uBitx challenges.? I know that I have trouble filtering the groups.io board for specific threads,? Will go back and see if there is a help/wiki to educate me. 73 Evan AC9TU? ? |
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
Hi Jerry,
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I read something in an ARRL publication about getting around that 40 dB dynamic range problem. Maybe by W7ZOI or W1FB. But it almost wants a spectrum analyzer to set it up. So it's a circular solution. Circular means chasing your own tail :) If you have a spectrum analyzer to set it up why do you need the toy analyzer? It might be doable without a second SA. 73, Bill KU8H On 1/21/19 10:53 AM, Jerry Gaffke via Groups.Io wrote:
If you want to pursue this, what you really need next is a step attenuator: --
bark less - wag more |
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
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Radios and projects like this one seem to want something to use for spectrum examination. Don't take it off list and hide it from the rest of us. 73, Bill KU8H On 1/21/19 10:42 AM, Evan Hand wrote:
I too looked at that Rigol.? My perspective is if I am going to spend that much, I might as well go all in and get the units that include the tracking generator.? Depends on how you will be using it.? Just to check for spurious emissions, or want to look at filter responses, detailed design analysis, etc....? There is a reason for the tracking generators. --
bark less - wag more |
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
If you want to pursue this, what you really need next is a step attenuator:
Kees is on the forum, he has a nice one here, kit #13 for $15:?? And a whole bunch of other stuff you could spend that $165 on. The RTL-SDR will be fine to learn with, a much better choice if you plan to burn out the front end with that transmitter.? (I assume you also have an up-converter, since those DVB-T dongles only down to around 30mhz.) If you wind up with a $2000 spectrum analyzer someday, you will still need the step attenuator. Yup, red flag that they say nothing about dynamic range on the RF Explorer, that's pretty basic info. Manual is under Documents here, describes a bunch of different versions of the RF Explorer: ? ?? Page 46 of the manual has a table showing "Measurable Input Range" when using various external attenuators, the figures they give are consistent with an 8 bit ADC (a 40dB dynamic range). ??https://www.seeedstudio.com/RF-Explorer-WSUB1-p-2986.html Get the vague impression elsewhere that it can see stuff between roughly -115dBm and 0dBm, but that could be done with an 8 bit ADC and a variable gain amp. So a very red flag. But I could be wrong in this, look forward to hearing further from those that have one. Jerry, KE7ER |
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
I too looked at that Rigol.? My perspective is if I am going to spend that much, I might as well go all in and get the units that include the tracking generator.? Depends on how you will be using it.? Just to check for spurious emissions, or want to look at filter responses, detailed design analysis, etc....? There is a reason for the tracking generators.
The unit you listed would handle the uBitx emissions testing. More on the RF Explorer: If you connect to a computer and use the software, it is really easy to shift scanned start and stop frequencies.? I will look again later this week (I am traveling on business and will not be able to "play") and let you know if I learn any more.? Will also try to take some pictures of the software to show you how it works. Maybe we need to take this off of the reflector and do it with private emails. My opinions only 73 Evan AC9TU |
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Re: Spurs/Harmonics fixes for v4 based on v5 board design?
On Mon, Jan 21, 2019 at 06:55 AM, Evan Hand wrote:
From my personal experience the RF Explorer seems to be good at the harmonics.? I have measured the 3rd harmonic at the same levels as reported by others (between 35 and 40 DB down), which gives me confidence on that front.? I have not been able to measure the reported spurs on bands above 20 meters.? Makes me question the usefulness for that measurement. Thanks interesting.? I wonder how much of a limitation that is... I wonder if running at 10khz it will pick up spikes at 1khz so you can zoom in later.. doing wide bandwidth first and then zoom in.. otherwise would have to scan up and down the band to cover it completely I guess. Another more expensive item I saw was this but no tracking generator but seems like one of the most reasonably priced new ones I've seen...? Don't think I'm ready to spend this kind of money though still. |
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