Re: QMX/QMX+ architecture
On Fri, 2025-03-21 at 16:42:35 +0000, Alan G4ZFQ via groups.io wrote: Presuming the QMX is like the QDX, in IQ mode there is no 12KHz offset.
The QDX manual has a good circuit description. Alain, Thanks for your response. I found the description of the receiver in CW mode in section 5.22 "AGC system" of the QMX operation manual (1.00_026/27). There it is described how the receiver signal passes through 25 steps of processing. From this description, also verified by tests, I conclude that the VFO is set to the dialed frequency with an offset of 12 kHz plus the side tone offset (nominally 700 Hz), assuming the the USB output during CW mode with IQ enabled is the unprocessed 24-bit output from the ADC. Maybe this description should be placed in a separate section, since it is not only of interest to the understanding the AGC system. I guess that a similar description will be needed for the new SSB mode, describing both Rx and Tx functions. Since I come from a different background (Automatic Control), I have some difficulties understanding the rationale behind all the steps in the receiver path. Why is the side tone frequency added already at the Tayloe Mixer/QSD mixer? An alternative would be to run the CW filter in zero-beat mode in the I/Q domain and mix the sidetone in front of the DAC. Zero beat is not a problem since there are no low-frequency noise nor bias after the 12-kHz mixing. A dual low-pass filter will then be needed, but the order of each filter would be about half of a corresponding bandpass filter. Also, the Hilbert transform (used for phase-shifting) can be removed and the Goertzel filter becomes a trivial moving average. A zero-beat indicator could be added to the display. The bandwidth of the low-pass filter is also easy to parametrize using Tustin transformations. If needed an offset of the center frequency can be added. The subsampling/decimation and interpolation steps can also be absorbed in the low-pass filter chain by implementing filter blocks with different sampling rates. 73 Anders SM5KAE
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Re: SWR and PWR does not show lcd
I've tried the "TUNE SWR" in "Hardware Test" and it works perfectly.
If I transmit, PWR and SWr indications don't appear on the top right side of the LCD display.
I have the "Display " option enabled in the setup.
THX
73's Miguel EC7ZV
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Martin,
I figured my QMX+ translates best, if the keyer speed is set to the approx. speed of the incoming signals. Be it received or when in practice mode. The manual hints at some parameters to play with for the decoder. My settings are the defaults.
Norbert, DA2CW
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I think it is unlikely that you could harm any circuitry by shorting the Vbat terminals together.
You could have drained your battery, if it was in for any length of time, since the + terminal could have shorted the battery + and - together.
So first thing is to try a new battery, inserted correctly.
And do you have your GPS set for Vbat power or Vdd?? If it is set for Vbat, and Vbat is drained, it won't keep time when off.? When you use the GPS for the clock, based on earlier messages in this forum, I understand you need to set RTC control to 'software' (due to a bug or 'feature' of the current firmware), in order for the GPS to continually update the clock.? [And note that the GPS may take a long time to get clock sync when you first turn it on in a new location - at least many minutes.? Subsequent sync times will be much faster.]
Stan KC7XE
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Re: Help with partially fried QMX
On Wed, Apr 2, 2025 at 08:29 PM, VA2OJD wrote:
Is there a single spot, somewhere on this forum, where it lists key measurements to check when troubleshooting?
Have you looked at this forum's wiki?? There is a topic specifically for the BS170s.? It has some helpful diagnostic guidance.? And you can search messages in this forum for BS170 and find a good number of entries, with different people being guided in their diagnostic efforts.
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Since your QMX was working for a good amount of time, a good possibility is that you fried your BS170s - most likely just them and not the driver and Q507.? This can occur, especially if you are running FT8 at more than 12.0V (for a 12V build) or 9.0V (for a 9V build).? Or if your QMX puts out more than 5W on a band at the correct voltage.? And especially if you combine over-voltage with some higher SWR on your antenna (probably more than 2:1), which can happen intermittently on wire antennas if the wind is blowing.? Doing any of the above over an extended time has risk of gradually beating your BS170s into failure.? That's why Hans has in big red print in his manuals to a) not run above 12V and b) not run above 5W.? And this is especially true with constant carrier modes like FT8, which add heat in the finals to the mix.? CW is more forgiving, because it is lower duty cycle.? At 5W the BS170s are pretty much up to their rated max, so going above any of the parameters puts more stress on them.? [This is true of their use in (tr)uSDX and other QRP radios, too.]
Stan KC7XE
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Hi,
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Although I got my licence over 40 years ago, I never pursued amateur radio as an interest until now. So, I was very excited this week to take delivery of my first HF rig - a new assembled QMX+. Even more excited, when connecting it to a homebrew efhw I could hear CW and see the decoded morse code (which I am currently learning).
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But all that excitement was marred by me being an idiot and not inserting the cr2032 battery for the RTC correctly. I assumed I just had to push it into the holder when I should have slid it in under the +ve connectors - so when the time was being lost on shutting down the rig I found that I had bent the +ve positive pins so they were in contact with the -ve terminal of the battery. I bent them back so when inserting the battery correctly they are now in contact with the +ve side of the battery but I lose the time every time I power down.?
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I have tried different configurations with the Real time clock parameter set to QMX+ RTC or software, manually setting the time or attaching the antenna for the internal GPS module and letting that set the time but with no success. So have I damaged the RTC components?
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Paul
G8MAD
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PS it was reading the posts in this group and all the support that it offers that made me decide to go for a QRP Labs radio. Thanks.
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Re: Help with partially fried QMX
On Wed, Apr 2, 2025 at 08:29 PM, VA2OJD wrote:
the middle, radiating contact of the BNC is connected to ground via T507??
Yes, of course.? In most radios with an internal SWR meter.? But this is DC ground.? RF flies through the transformer almost untouched.
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On Wed, Apr 2, 2025 at 07:43 PM, Rick Hill wrote:
Does anyone know if the GPS module disciplines the clock or VFO frequency
The clock, yes.? The VFO freq, no, if I understand correctly.? That could be added to a future firmware update, I believe.
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Yes it does on my QMX+. You might check your battery.
John KK4ITX? ?Each mistake is a learning opportunity.?
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On Apr 2, 2025, at 10:44 PM, Rick Hill via groups.io <6xraytango@...> wrote:
? I have noted that my RTC is wildly inaccurate, gaining 7 minutes overnight. I have removed it from the display...do not really need it. Does anyone know if the GPS module disciplines the clock or VFO frequency ??
de VK6XT?
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GE Martin,
I would start with the settings that are in the manuals, then;
* Turn the volume down! If too loud it’s hard to translate.
* Next adjust your filters correctly?
* Try to use the Noise Blanker
The rig needs to hear the cleanest signal you can feed it. When it’s not clean you get “*”.
Sometimes you have to move slightly off frequency to get the best results.
You can usually achieve 70-90%, you have to be able to fill in the blanks.
The QMX+ seems to be better than my 3 QCX rigs but I am new with the QMX+.
Hopefully this helps,
John? KK4ITX? ?Each mistake is a learning opportunity.?
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On Apr 2, 2025, at 11:10 AM, Martin DK3UW via groups.io <m.sellschopp@...> wrote:
? Hi My reader is very erratic with a lot of *. can someone who has a good setting let me know how they are please
--
Martin
DK3UW
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Re: Help with partially fried QMX
Hi Steve.? Thanks.
So even the CENTER of the BNC?? the middle, radiating contact of the BNC is connected to ground via T507?? MyBS170s look fine.? Is there a way to test them?? It makes sense that they would pop first, but i've no idea how to test them.??
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Is there a single spot, somewhere on this forum, where it lists key measurements to check when troubleshooting?? I must have made Google a million dollars in eyeball hits in my searches over the last week.
?TNX again!
JD
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Re: QMX+ rev 3 freezes shortly after boot
Alright! I've got some updates.
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I pulled off the front panel and did a close inspection of the display connections, didn't see anything obvious but cleared out some plastic and some small fibers, possibly from my sweater or ambient dust.
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Checked R110 and R112, both of those appear to be in fine condition. During normal operation both read at around 1.6V.
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Checked resistance between VDD & VCC. When my positive probe was on VDD & ground probe was on VCC, the resistance started at around 3.2kΩ and maxed out at around 4.46kΩ.
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When my positive probe is on VCC and ground probe on VDD, it starts at 2.8kΩ then climbs up to around 6kΩ, then there's a spike up to 28kΩ, then it descends back down to and stabilizes at around 7kΩ.
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I checked D109 and it seems good as well - no obvious heating or anything like that.
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No GPS currently installed, and it wasn't installed during any of my earlier tests.
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Now for the interesting part. After checking all of the above, I turned it on and held steady for about 5 minutes. So I thought I'd try out the terminal again. This time I was able to connect! Previously, it would freeze at the exact moment I hit "enter" to initiate the serial connection. This time I was able to open the menu and even run some diagnostics! Attaching the screenshot from the diagnostics view below.
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In fact the terminal session was going so well, I thought I might've cleared up whatever the issue was. Unfortunately, it froze again shortly after that. I believe I'd entered into the RF Filter Sweep menu item and was watching the output when I saw the current jump from 0.8A to 0.20A and cut the power.
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The only substantive things I can think of that I did were:
- I unplugged the front plate and removed some melted plastic from the very top left female port of JP215
- I used the tip of one of my probes to clear out the channels between the pins of JP215, JP216, and JP201
- I took my and blew out some of the fibers I saw
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I am wondering if it's temperature related or possibly related to a capacitor somewhere(?), because it seems to perform much better after 10+ minutes of no use, vs 30 seconds to 1 minute of no use. If I wait 10 minutes or more, I can usually get a good few minutes of use, but if I only wait a few seconds or a minute after cutting power, it will either start in the frozen state, reach the frozen state after a few seconds powered on, or the screen wont power on at all, and rather than drawing 0.20A, it'll draw about 0.14A.
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I have noted that my RTC is wildly inaccurate, gaining 7 minutes overnight. I have removed it from the display...do not really need it. Does anyone know if the GPS module disciplines the clock or VFO frequency ??
de VK6XT?
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Re: Debugging BS170-related issues
Success !
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When in doubt, try the simplest thing first.
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After an afternoon spent looking for the esoteric solution, I touched up all the IC503 pins with the soldering iron.
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4-5 watts on all bands, again.
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Many thanks to Ludwig, Stan and Chuck for their help.
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73,
Steve, N2IC
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Re: Help with partially fried QMX
You will always see DC continuity from the BNC connector to ground through T507.
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For no power output, start with the BS170's. I just went through this, frying the BS170's, IC503 and Q507.
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73,
Steve, N2IC
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Re: Gibberish characters appended onto end of Message 1
Thank you very much! I've never heard of it, but I am not a techie so that's not surprising.?
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Re: Available Hand Mics for QMX SSB ?
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Re: ProgRock2 programming??
Thanks Alan, I’ll measure the xtal socket and see what’s on each pin. I’ll have to be careful to put the voltage pin on a socket with 5v regulated voltage.
73 Tom
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On Apr 2, 2025, at 1:50?PM, Alan G4ZFQ via groups.io <alan4alan@...> wrote:
?On 02/04/2025 14:59, cct314159 via groups.io wrote:
- Even though they are "rated" for "12 volts" *don't even think about running one at that voltage:* I'd avoid going above 10.0 volts. Yes, that reminds me. I tested with 12 volts and it certainly got a lot hotter than I expected.
The ones I use are fed from 5 volts and keep cool.
73 Alan G4ZFQ
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Re: Gibberish characters appended onto end of Message 1
Hi Braden
Putty is the favoured terminal software, works on Windows and Linux.
73
Roger
8P6RX
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OK, I'll have to find out what software goes with the QMX. So far, seems buggier than an Amish church meeting.?
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Thanks for the ideas – so a bit of probing and VDD to GND is like .5 ohms – without the smps board installed . Any ideas where to start looking for the short? ? thanks ?
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From: [email protected] <[email protected]> On Behalf Of Stan Dye via groups.io
Sent: Monday, March 31, 2025 1:24 AM
To: [email protected]
Subject: Re: [QRPLabs] Lin_reg_en #troubleshooting? Also inspect carefully the interconnect of the LIN_REG_EN signal fromthe smps card to the main board, ensuring nothing there is pulling it down.
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KK4ITX John
Michael Shiplet
Braden Glett