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QDX Died shortly after arrival
5
#qdx
The 12v QDX HB that I ordered pre-built arrived Monday the 23rd of Dec. It is replacing the rev. 5 QDX HB that I bought pre-built in May '23 that has developed an aversion to heat - it stops TX after it gets warm. I think a SMT component is lifting as nothing seems to be an issue otherwise (Jeff Moore looked at it three times). I tested the new one into the dummy load at 11 volts (how I operate these) and confirmed nice power out on all bands with 3.7 watts on 10 meters via "tune". On FT8 into an antenna at an SWR of 1:1.2 I was seeing 3.4 watts out. It worked fine for two hours the first afternoon and another hour the next afternoon when I noticed the power out rose to 4.0 then dropped to 3.8 on one CQ call. On the next cycle the magic smoke escaped, JTDX offered to reconfigure because the radio had disappeared, and I saw that the QDX was drawing the max of 1 amp at 5 volts from the Drok buck/booster supply. I cannot see what burned nor where the smoke came from. I can smell the smoke stronger on the top of the board than on the bottom this morning. I tested the Drok with the QDX LB and it is working fine. I then connected the smoked QDX HB to the Drok and it again hit the amps limit of 1 and volts dropped to 5. I am rather disappointed in the three hour life of this new QDX and don't know where to start looking for the short/fault - source of the smoke. I submitted a support ticket today, but hope no one is reading them now!
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Power Source for 50 Watt Amp for QCX Series
18
What power supply are you using for the 50W amp for QCX Series radios? 20V, 13.8V or 12V ? What is the best way to get 20V ? Thanks ! Jim WB4ILP
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QMX and FLDigi - MFSK modes
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I've been trying to get my QMX to work with FLDigi, and had a long and detailed post typed up recounting my troubleshooting, but I think I may have made a breakthrough, albeit one that leaves me disappointed... The QMX is only able to do single tone FSK modes, correct? So something like Olivia or Contestia or even RTTY that uses more than one tone at once is not possible on the QMX with the current firmware? This would explain why "TUNE" mode on FLDigi generates an output but as soon as I try and transmit Contestia it cuts out. I was able to get MFSK32 to transmit but it was not decoding for me, which would make sense... If this is true this appears to cut out the majority of digital modes available on FLDigi, since PSK is out as well... Is anyone operating FLDigi with their QMX, and on what modes? Thanks, N1EDC
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I have not been able to configure fldigi on Windows 10 to work with QMX+. WSJT-X has been working just fine. Can anyone suggest the correct settings? Hiroki AH6CY
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Hello experts 😊 I just finished my build of the QMX 10-20m. During the first tests I found that the device is absolutely deaf on all bands. Measuring the board I figured that I have a short over all contacts of the antenna jack. I removed the jack. But still I do have continuity over all connection point. Does anyone have an idea where to look next? Vy73 de Rico, DG5BQ
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QMX+ thank you Hans
Hans, Thank you for designing and producing such an excellent radio and kit. I received my kit in August and finally got it built just before the holidays. I have been on JS8 on 10m and recently switched to 40m and have been amazed to see where I've been heard with such a simple setup. Merry Christmas and Happy New Year Darrell KI4RXJ Kansas, USA em28gx
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QMX 60-15M kit order?
3
Has anyone recently received their QMX 60-15M kit order? The last update, December 9th, on QRP Labs website said they were short ferrite cores which were expected December 13th. No updates since then. Brien - KE7WB
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QMX+ with HardRock 50+ amplifier
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I am about to order a QMX+ which I plan to use with my HardRock 50+ amplifier/ATU. The HR-50+ will operate in "QRP mode", in which the ampifier is switched off and the ATU is still operating; this will allow running the QMX+ at 5 watts while utilizing the ATU in the HR-50+. With the HR-50+ amplifier enabled, the amp will crank out 100 watts. My experience using it (with my Elecraft K2) is that it can take as little as 2 watts input to achieve 100 watts output. If the HR-50+ thinks it's being over-driven, it will take itself off-line. So, to get to my question: I presume that I can decrease the QMX+ output power by decreasing the power supply voltage. In that scenario, does it make a difference whether I build the QMX+ for 9V or 12V? A few years ago, I built the QDX and opted for the 9V supply (I think my reasoning was that cautions about blowing out the BS-170s were associated with the 12V supply) and I would probably make that choice for QMX+ as well ... if that is consistent with lowering the supply voltage when used to drive the HR-50+. Is there a point at which the QMX+ will cease to function if the supply voltage is dropped too low? Would it be better to construct some sort of variable pad to decrease the QMX+ output power? Thanks all!! - Bruce K1FFX
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Which Hardrock Amp
17
I need another kit to build, so I'm thinking of a Hardrock 50 or 50+ (100w version). They are both around $350, so price is no issue. It would be great if Hans had an equivalent. Any thoughts.
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What are the current links to BOM and Build Instructions??
Cal, Now that you have ordered the PCBs, can you please point us to the correct BOMs LINK to use for Digikey and Amazon. I purchased my Digikey and Amazon parts from a previous BOM listing 3-4 weeks ago and need to cross-check what parts changed or I am missing. Also please point me to the current Build Instructions LINK, too. I mailed my check on Dec 23. Happy New Year. Glen, WB4KTF, Austin, TX
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QMX Heated Up, now no output
6
Using the same power supply (11.8v via BUC converter) and same antenna (Resonant 40m) that had been working for an hour, suddenly the unit quit putting out RF and when I put my hand on it it was very hot. Disconnected power of course, and verified the SWR was still 1.3 on the 40m antenna. This is an assembled unit from QRP-Labs. I've done a reset via the menus, and let it cool overnight, no overheating now, but it's drawing slightly more current (0.12 increase to 0.24) at idle, and doesn't draw anything more at transmit. I don't know where to start.
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Happy Holidays to all and may 2025 be happy and prosperous to all.
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Michigan QRP Club Zoom meeting invite and report
We had thirteen folks at the 19 December Michigan QRP Club weekly Zoom chat. Please join us Thursday 26 December (and every Thursday) at 4PM Eastern for the Michigan QRP Club weekly QRP Chat where the main topics will be QRP and other ham interests. New hams are encouraged to participate and ask questions. It's fun, it's easy, and it's free. You only need a computer, a smart phone, or a tablet that can connect to the Internet. OR if you can't be close to any of those you can join by audio with any standard phone. Just follow the directions below. No software needs be loaded or installed. Anyone can join and non members are welcome. Details are here: https://www.miqrp.net/zoom Thursdays topic will be a review of ham radio gifts received over the holidays and the Michigan Mighty Mite transmitter. Pete WK8S Dave N8SBE Ed AB8DF Ernie W3ETE Stan WB8QJZ Stuart M0SGV Steve KE8KF Mike K7FZD Jacob N3JU John M7FZC Casey KC9IH Neil N9NL Yvon AE7YD That big radio space dish in Puerto Rico collapsed. Pete talked about his K1EL transceiver kit the Open QRP 40. He has just finished it and made one contact. Needs to tweak the sidetone level. Latest QRP Quarterly has a 30 meter DC receiver project. Ed will be continue his CW practice now that he is back from Egypt. John is using his balcony with a new ATU URT1 tuner. https://chameleonantenna.com/shop-here/ols/products/cha-urt-1 Santa came early to Erie’s house with a KXH-1 https://elecraft.com/collections/kh1-transceiver/products/kh1-f. He is thinking about different antennas to use with it. Including a 22 ft zip cord antenna using speaker wire. Both Pete and Ernie got new paddles. Casey is waiting on a new High Gain Vertical. It has been bouncing around the country. The topic for December 26 will be an open forum for any questions, a quick review on holiday gifts and the Michigan Mighty Mite. Anyone can take the floor and ask questions. We will go one by one until all have had a chance to have the floor. Files, pictures and presentations can be shared if you have any. There will be time for comments and questions. Please try to stay muted when someone has the floor. Thanks Ed AB8DF
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Other rotary encoder for QMX and QMX+?
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Hello I am using a QMX and QMX+, but do not like the encoder to tuning the band up and down. Every step is a grid. Is there a replacement possible for the rotary encoder to tune the bands like on a K1/K2? 73 de Harry, DK2GZ
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From the NASA Spec: 6.11 Solder 1. Types and Usage. All solder used for tinning and solder connections shall conform to ANSI/J-STD-006. Flux-cored solder shall be either composition SN60 or SN63 containing flux types R or RMA, or equivalent. For all soldering applications where adequate subsequent cleaning is not practical, only solder containing flux type R shall be used. Solid solders (no flux) for use in solder pots shall be of the same composition. 2. High Temperature. For soldering operations where connections are to be subsequently reheated, the use of high temperature solder alloy is permitted (e.g., SN96AG04A). The type of high temperature solder and the connection requiring the high temperature solder shall be specified on the engineering documentation. 3. Variations. The use of any other solder compositions and forms (including type RA flux) shall require the approval of the procuring NASA Center prior to use. 6.12 Liquid Flux 1. Types and Usage. All fluxes used for tinning and soldering operations shall conform to ANSI/J-STD-004. Process documentation shall describe the types of fluxes, where each is used, and the necessary precautions. 2. Rosin Flux. Flux types R, RMA, or equivalent shall be used. For all fluxing applications where adequate subsequent cleaning is not practical, only type R, or equivalent, flux shall be used. Liquid flux used with flux-cored solder shall be chemically compatible with the solder core flux and with the materials with which it will come in contact. 3. Variations. The use of any other flux compositions and forms (including type RA flux) shall require the approval of the procuring NASA Center prior to use. The request for approval shall include detailed flux removal, cleaning processes, monitoring requirements, and cleanliness test methods. 6.13 Solvents and Cleaners 1. The solvents or aqueous cleaners used to remove grease, oil, dirt, flux, or other debris, shall be selected for their ability to remove both ionic and nonionic contamination. The solvents or cleaners used shall not degrade the materials or parts being cleaned. A list of approved solvents and cleaners is provided in Table 6-1. Mixtures of the approved solvents may be used. Solvent containers shall be properly labeled. Refer to Material Safety Data Sheets (MSDS) for proper handling of solvents or cleaners.
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Retiring after decades in the software world, I'm now returning to the hobby of my youth, ham radio. I purchased the QMX+ kit and look forward to building it. With the great documentation from QRP Labs, YouTube videos, and support on this group, I expect that I will have few if any problems. (Fingers crossed!) I need to update my soldering station and I see a lot of relatively inexpensive equipment on Amazon. I'm willing to spend a few hundred USD, but not much more than that at this stage. Looking for magnifier/lamp, work holders, iron (brand, watts, temp control?), fume hood, etc. If anyone has any passionate recommendations, or even just solid recommendations, I'm all ears. BTW: I see that lead-based solder is still available for purchase (I thought it was banned years ago). What kind of solder should I use on the QMX+ kit? What thickness? Rosin core or not? (The QRP Labs build instructions don't mention soldering materials.) Also: Separate rosin paste dispenser/brush? 99% Isopropyl Alcohol? Anything else? I have a reasonable amount of soldering experience, but that was long before the RoHS era. I want to build the QMX+ boards the right way with the right materials and equipment. Many thanks for your input! (I hope this isn't a controversial topic!) Happy Christmas!
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Holiday Wishes
Merry Christmas, and Happy Holidays to all from Upstate New York, USA. May your Holidays be filled with peace and love, family, and ham radio friends from afar. -- 73, Dan - W2DLC
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Happy new year
Hi all, may I wish you all a happy new year and say a big thank you to all you builders who post questions on this site. I look forward to the daily digest each morning to read the queries, it starts my day with a smile, sometimes a full blown laugh.
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USB-C to USB-C cable recommendation
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Would someone recommend a good well RFI shielded short (1-2 feet) USB-C cable? Hiroki AH6CY
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I've been annoyed by the audio quality of some earlier kits, so I asked a friend, an expert builder, to borrow his newly completed QMX+ for a listen. The results are quite bad. Attached are several recordings taken with Audacity from the earphone jack. Also attached is a spectral snapshot of a portion of the SSB recording --- notice the distorted envelope. Also notice the high hiss content of both modes and the 'fur' (phase distortion) on the CW filter. Not good. I think I'll pass on this kit. Chuck w8mqw P.S. There's the chance that my data is flawed. I would be delighted to be disabused of these awful results.
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