QDX + Digital Radio Mondiale
7
Hello there , New Ham , New QDX user where the radio has been donated to me by TRAC friends in Istanbul. I reached Australia , Antarctica and Greenland with a 5 volt pc supply and an untuned cable antenna dropped from a window on a concrete wall. Now , I want to transmit a few hours daily in - digital radio mondiale - mode and I will make a pirate radio. Can QDX help me ? Umut TA2JCO
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#qcxmini #qcx-mini Weird behavior BPF
3
#qcxmini
#qcx-mini
I thought I posted this this morning but can't find it, I hope I haven't made a duplicate post and apologize if I have. I just finished my first build, a QCX Mini in 40m. I'm having an issue during the alignment phase. I have confirmed that I have continuity on common legs of T1 and have reheated the solder points to ensure the enamel has been removed and there is a good connection. I've found a strange thing though, at least I think it is strange. If I apply a little pressure to the middle top or middle bottom of the display my BPF reading goes from 3 to around 9 or 10 and is adjustable. If I let go of the pressure the reading drops back down to 3 or so and won't go higher. I tried a hack, just to see if it would work, of putting some paper between the case and the top of the display board but it doesn't change things. I removed the top right standoff to see if maybe I wasn't making a good connection at the 2x5(maybe it is a 2x4) connector but that didn't change anything either. I've gone through and checked solder joints throughout the board but see nothing standing too proud or that didn't appear ok. I've counted the windings on T1 and it appears to be right for 40m. Can anyone lead me to where to look next? It is just strange to me that a little pressure makes a difference when the only thing I did on the display board was solder the screen itself on and the screen appears to be functioning properly. The photo with the circles is where it seems that a little pressure has the desired change to the BPF. I have a DVM and just found my cheap, Amazon special, oscilloscope but I have no clue how to use it to diagnose a problem.
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Fw: [QRPLabs] 6m Phase error vs DAC
Ooops, My QMX should read my QMX+. 73 Ian G4GIR ----- Original Message ----- From: Ian G4GIR via groups.io <jean.frith@...> Reply-To: <[email protected]> To: <[email protected]> Sent: 03/05/2025 10:46:17 Subject: Re: [QRPLabs] 6m Phase error vs DAC Just checked out that Wiki article. /g/QRPLabs/wiki/39506 Hans quotes:- "Note that on QMX+ I have never seen this occur;" Hans this is happening on my QMX! The last kit I purchased from you, the previous two kits don't have this problem Can I claim a first!! Lol. 73 Ian G4GIR ----- Original Message ----- From: <DH8WN@...> Reply-To: <[email protected]> To: <[email protected]> Sent: 02/05/2025 16:33:58 Subject: Re: [QRPLabs] 6m Phase error vs DAC Ian, there was a discussion about this some days ago. Please read QMX QMX_plus SSB Calibration and Predistortion from the QRP Labs wiki to find the relevant text, about 'calibration not possible' especially more at the end. 73 Ludwig.
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Hi-Band QDX transmit trouble
2
I had been puzzled for a while because I couldn¡¯t get the device to transmit on the 20m band only. Again today, I played around with various settings, hoping to fix the issue. While modifying different parameters in Terminal mode under the Config menu, I discovered something unexpected. It turns out that if I set 'Japanese band limits: ENABLED' in the Configuration, it restricts transmission to the 20m band only. When I switch it back to the default setting 'DISABLED,' transmission becomes possible on all bands! What a surprise! I really think this should be clearly mentioned in the manual. With this, I now have a lineup of two units ¡ª the 5-band version (80¨C20m) and the Hi-Band version (20¨C10m). I couldn¡¯t be happier! JA1TLH/Taka
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6m Phase error vs DAC
4
Can someone explain this error please? "Phase Calibration not possible" 73 Ian G4GIR v .009 QMX 3 v .009 QMX 3 Final screen
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QCX Mini - C39 broken off
2
#qcxmini
I took the PC Board for the QCXmini out of the plastic envelope and after inspection found that C39 had broken off, probably in transit. There was a CAP in the box, so I soldered it back in place. I am afraid, however, that C39 was damaged, since it appears to be missing the silver metal end on the right side. It may be that it is only the solder packed up agains the broken end and it is not making an electrical connection. I do not have any .1uF caps of similar size to replace. Should I continue with the build, and find out if it is broken when I finish the build? Or should I try to find another one before moving on? There are several imprints of other SMD components on the bag that the board came in, so I suspect the problem is that the board was backed too tightly in the box, rather than an assembly problem. Box arrived seemingly undamaged from MO. Thanks for your thoughts. Phil, K3UT
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#qmx SSB Firmware beta 1_01_007 release
44
#qmx
Hi all I updated the SSB beta testing webpage of the brave, here: https://qrp-labs.com/qmxp/ssbbeta.html and released firmware version 1_01_007 to it. This fixes one more typo I found in the USB compound device configuration. I carefully checked all 440 bytes one by one in all three configurations (1, 2 and 3 serial port). I believe in the 1-port configuration the configuration is byte for byte, identical to 1_00_027. Waiting for Ludwig to confirm any issues or not with WIn 7. I booted my PC into Windows 10 on the old HD and all three serial ports worked properly, and audio too. 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl
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de minimis shipping to US from China is ending
5
President Trump has signed an Executive Order that ends the tariff/duty exemption on small value shipments (i.e. < 800 USD) sent from China to the US. It is not made clear if this change will apply to shipments from other countries as well. This will certainly impact those of us who purchase PC boards, electronic components and modules, and equipment in pursuit of our hobby. 73, Ben K0IKR Here is text from the US government: ¡°Today, President Donald J. Trump signed an Executive Order eliminating duty-free de minimis treatment for low-value imports from China¡¡± ¡± Following the Secretary of Commerce¡¯s notification that adequate systems are in place to collect tariff revenue, President Trump is ending duty-free de minimis treatment for covered goods from the People¡¯s Republic of China (PRC) and Hong Kong starting May 2, 2025 at 12:01 a.m. EDT. Imported goods sent through means other than the international postal network that are valued at or under $800 and that would otherwise qualify for the de minimisexemption will be subject to all applicable duties, which shall be paid in accordance with applicable entry and payment procedures. All relevant postal items containing goods that are sent through the international postal network that are valued at or under $800 and that would otherwise qualify for the de minimis exemption are subject to a duty rate of either 30% of their value or $25 per item (increasing to $50 per item after June 1, 2025). This is in lieu of any other duties, including those imposed by prior Orders. Carriers transporting these postal items must report shipment details to U.S. Customs and Border Protection (CBP), maintain an international carrier bond to ensure duty payment, and remit duties to CBP on a set schedule. CBP may require formal entry for any postal package instead of the specified duties. The Secretary of Commerce will submit a report within 90 days assessing the Order¡¯s impact and considering whether to extend these rules to packages from Macau.¡±
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Power Supplies
It is really necessary to have a very clean, power supply with low ripple. This is especially noticeable on WSPR where you will see spurious signals either side of a strong signal on both RX and TX if there is residual 50 or 60Hz from your power supply. I built up this unit using a modified "Studer 900" PCB in a blank QMX+ enclosure. Fully analog with discrete components!
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Do I have a 9 or 12 volt qdx, qmx
5
I purchased both a QDX and a QMX at an estate sale and I'm not sure which voltage they are built for. I see in the manual that the T1 transformer can be wound 3:3 or 3:2 depending on what voltage choice was made when being built. How can I know for certain which voltage I should use? I really don't want to disassemble the transformer. Is there another way? Attached are photos of the QDX T1. Chris - KE8VOD
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QMX PTT timing
9
Is there a way to modify the PTT timing to run slightly ahead of transmit in semi QSK mode? I'm trying to configure the QMX to operate with an SDR switch, but it's pretty consistently tripping the SWR protection (even when transmitting into a dummy load downstream of the switch). I'm thinking that this is happening because the relays have not settled before transmit starts. Greg, N1TR
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Audio Setting on QMX +
4
Hello all, in order to have a good audio volume on WSJT-x (the green slider on the left of the WSJTX screen) I adjusted the audio level per band and some had to be set up to 70 istead of the default 54. So far so good but now I can not turn down the audion for the headphones down to 0. No I don't have the headphones on in DIGI modes :-) , but that applies also to CW and there now the audio is too loud for me on some bands. Could the audion setting be different for Digi and CW or SSB ? I believe the default setting would be fine for any mode except DIGI. -- Martin DK3UW
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Amplifier suggestions for the QMX+
13
Hi, I'm looking for amplifier recommendations to boost the signal on my QMX+. It doesn't have to be more than 10W or so. I have considered the QRP Labs 10W amplifier, but I think it needs a band pass filter for each band? I'm not an expert on amplification. The chinese have some offerings for QRP transceivers - I understand one of them is not that good ( the 50W HF Power Amplifier for USDX) but are any of the other ones worth a look? Any recommendations or other tips? THX!
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installed firmware version 1_01_009. Ran full configuration. Bad things happened.
9
My QMX+ was built by QRP-Labs. It has worked well for about a month, listening and practicing CW. Today I upgraded from 007 to 009 and ran the full configuration routine with a dummy load. The radio felt warm, not hot. It is connected to an OCFD antenna with a SWR a bit below 2.0 on 10 meters. I cancelled Practice Mode, started sending QC while monitoring the SWR (about 1.8 on the display). After about 1 minute, the QMX+ shut down. When I turned it on again, the display grid was all black dots. I removed the cover and adjusted the display pot so it was readable. Turned the radio on and sent CQ a few times. After about 10 seconds the radio shut down again (and again, and again). I performed the factory reset (Twice) and reconfigured the QMX+ for my key and display options (SWR and battery). At this point the radio will power up, the display looks correct and the menus work. CW Practice Mode works, except each character is followed by a loud POOP! Transmitting CW or SSB causes the radio to reset and sometimes it shuts off. Any help is appreciated. Be kind (I've had a difficult day) 73
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lightAPRS22
Can I ask Questions about this here? https://qrp-labs.com/lightaprs2 Or is there a separate group to discuss this tracker? Joe WB9SBD
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Feature request 500/600Hz-Filter for SSB-mode
2
Hi Hans, first of all: I am very satisfied and happy with my new QMX with SSB beta firmware. Would it be an very big effort to implement 500/600 Hz TX/RX-filter for SSB-Mode in the future? Vara500 for VarAC and Winlink are already working successfully with the new SSB firmware, even with "normal" 2500 Hz filter intended for voice. But it would be smoother for narrow modes like Vara500 or RobustPacket (RPR) to have an more narrow filter. Thank you!
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Loud pop sound in 32 ohm stereo headphones when powering QMX on and off
4
Hello, Has anyone else experiened this quite loud noise with their QMX? It is using the latest software and I am using it with a 12 Vdc 1.5 Amp switch mode power supply. Best regards Richard GW4MTE
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QMX+ beta USB ports - mode CAT or terminal
3
So this is, perhaps, interesting. When at QTH-R I use the QMX via flrig and this has worked well for some time. Now when using the beta/ssb software flrig does not connect immediately and I have found, by connecting a terminal to that port ...if00 that it thinks it is several layers down in the terminal application ( it is only just switched on ). Will investigate a bit further, it may be that I need to look at the preamble from flrig or perhaps only configure one port ( have configured for three). Just wondered if anyone else had experienced this? Shown below is how putty shows up after trying and failing to connect with flrig on QMX+ switch on. 73 Simon G0FOZ
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SSB audio distortion #qmx #SSB Firmware beta 1_01_003 release
47
#qmx
#ssb
Well, I bit the bullet and installed the 003 FW. Update of FW went all fine, no issue there. I wired up a electret mic I found in my junk box. Tested the mic on pc and sounded fine. I made an adapter using the electret mic and a foot switch for ptt. The Mic and ppt switch works. But... Testing SSB TX with QMX on dummy load and listening on my ICOM 7300, the audio is badly distorted before calibration and even worse post calibration. So much so that the speech is unintelligible. The audio sounds like the QMX is only picking up the peak signals from my voice. Most of the calibration plots look nothing like the example ones from the release notes. And only a few mildly resemble the examples. Adjusting mic gain to about 70 seems to improve the audio. However, every time I key up, there is now an awful lot of noise before I even start speaking. Once I start speaking the audio is ok'ish with a load of background noise. I tried messing about with other SSB settings with no improvements. I did find a second electret mic that gave me similar results. I have now set it back to factory default and seeking advice. Any suggestions? Mel. M0KMD.
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QDX Toast for Breakfast
4
#smoke
#ibreakfast4mosfets
#qdx
While you have the BS170s out, consider installing sockets. Cut three pins off of a machine-pin DIP socket with a Dremel tool or a teeny tiny modeling saw. For the 3 and 3A boards, you have to spread the two end pins out a little bit to get them into the holes in the PCB. For 4 and later boards, the pin spacing is perfect. 73 Jim N6OTQ
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