Matt, be happy with what you have. The levels you report are very typical of the QMX line. No one will EVER tell the difference between 4.5w and 6.1w. The difference is miniscule. And, no one in the QRP community will notice either. Your antenna blowing in the breeze will cause more variance than those power differences. Look for some YouTube videos comparing different power output levels and you'll discover that doubling the QMX output power will, at best, be less than one half an S-unit at a receiver.? What you are trying to do is like counting Cherrios in your cereal bowl.? Instead, continue enjoying these tiny remarkable radios.
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P.S. I just had a POTA contact yesterday between Central FL and San Diego using a backyard vertical and a new QMX+ with 3.98w on 20m.
--
72 de N4REE, Bob Easton - QRP CW forever
https://bob-easton.com/n4ree
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Here's hoping for QMX+ v2
Wouldn't it be loverly if the next version of the QMX had a display like the zBitx.?
Hans has done some amazing work with the QMX, with SSB and with bringing us some absolutely amazingly good quality radios and kits that definitely punch above their weight class.
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Thanks for everything you've done Hans. Can't wait to see what comes out of the QRP-Labs stable next.?
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Re: Hand Mics for QMX SSB ?
I bought similar one from QRP guys and yes the jumpers goes straight. For windscreen i used the one from Amazon, fits snuggly.
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8pcs Headset Microphone Foam...
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--
73
Ingy
M0MHJ
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Re: Does the QMX need a mic preamp? #qmx #QMXplus #SSB Firmware beta 1_01_003 release
#qmx
#QMXplus
#ssb
Hi Don,
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I didn't want to be invasive and have the risk of breaking something in the QMX to source a 3.3v line. I will stick with the 3v battery pack.
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The idea was to be able to use any generic electret capsule and boost the audio to an acceptable level to drive the QMX. Having to use a specific capsule narrows down options.
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Cheers.
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Mel. M0KMD.
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Hi Todd,
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Connectors were my first call. I resoldered them all again and also tested with display from other QMX I have.?
I got the same results.
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---------------------------------
73 de Marek SP9TKW
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Re: Hand Mics for QMX SSB ?
Try aliexpress: ?
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Lots of sizes to choose from.
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Re: Hand Mics for QMX SSB ?
Hello Larry
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I know nothing about question one, but a wind screen for a microphone can be made from various bits of cloth (even old socks!) and the appropriate way of attaching it to the microphone. Rubber bands, cable ties, ribbons, tie wire.... anything similar should work. Also try various type of foam rubber for the wind cover. I have used a tea towel on a microphone for film sound recording and in a difficult, windy location it will work well enough to save the day!
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Ian
VK3YCQ
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This is a valid test for the 5V smps, if I understand correctly that you removed it and are testing it separately.
However, the voltage and current you are using could potentially cause further damage.? Can you limit your power supply current to 100mA?? or 250mA?
Since you are getting 400mA immediately, there is a short or malfunction somewhere in the 5V smps.
Please see this wiki entry for a complete power supply test procedure:
Be sure to do all the tests, and test all the pins.
But we already know two issues:?
1) You just reported PWM_5V being at 5.6V.? This is bad; it should be at 0V.? It has a pull-down resistor to gnd.? It is likely shorting to something else on the PCB#1 card, which is pulling it up high.? This will cause the 12V to constantly drive through Q108 and the D108 5.6V zener diode will conduct all of the excess current, trying to keep the voltage rail at no more than 5.6V, but it is getting up to 6V, driving the zener hard.? Since you are seeing 6V on VCC and 3V at ADC_5V, it means you haven't yet blown D108 - but if you keep feeding it 400mA, it may also blow.? So this problem with PWM_5V is likely what is drawing most of the current.? So one task is to find what is causing it to go high.
2) You previously reported auto power-on/shutdown, so either a) or b):
a) the PWR_ON signal is shorted low, either on the PCB#1, or on the main board.? So check it in this PCB#1 test - it should be pulled up to almost Vin.? If it is even a couple of volts lower than that, it will auto-power-on, and you need to find the reason.? If it is properly at Vin, check on the main board the resistance between this control pin and all the other pins in the connector - they all should have a very high resistance.?? If any have a low resistance or continuity, that is a problem that must be fixed.? If all of this is OK, then check b):
or b) the PWR_HOLD signal is shorted high, either on PCB#1 or on the main board.? This does the same thing as PWR_ON, but is the opposite polarity.? It has a pull-down resistor, and should stay at 0V on the PCB#1 tests.? If it is higher than that, find out why.? If not, check the signal at the connector on the main board - it should have high resistance to all other pins on the connector.
One possibility is that your PWM_5V signal may be shorted to your PWR_ON signal - they are adjacent pins in the connector, and that would cause both of the symptoms you are seeing.? But the PWM_5V may be a little to high for this explanation, so maybe it is something else.
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I hope this is helpful.?? Good luck
Stan KC7XE
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Update:
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I replaced L501 just because the broken corner was bothering me.? It didn't have any impact on the problem.
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I've ordered some transistors to shotgun in to the bias circuit.? I'll update the group when those semiconductors arrive and are installed.
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Thanks for listening.
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73
Andy
WB9YXA
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My output wattage on the original finals was a bit low anyway. With the larger FETs it was still about the same but with the ability to run at a higher input voltage if desired, it was easy to make up any differences plus a bit more. I did some preliminary checks and overall the output is better except like you said the higher bands suffer a bit. For me, it is good enough and gives me some leeway for output. The lower bands 80m, 40m 30m do extremely well. They are up to 7W-9W range. I believe they are 10W components so there is a lot more overhead and with the 150V max voltage they are less likely to burn out. For now that's my story an I'm sticking to it until I break something else. Experimenting for me is part of the hobby. YMMV.
Tim - K5DEZ
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Attached is display on my new plus. ?It will
change when I manipulate the encoders but never anything worthwhile. ?
RTFM hasn’t helped much likely because I’m an old timer who shouldn’t be doing this stuff anymore. ?Help would be appreciated!?
Will try for a reset and try to do a hookup to if that’ll reveal anything. ?
Jim w0nkn
toggle quoted message
Show quoted text
On Apr 8, 2025, at 9:57?PM, james jones via groups.io <j2@...> wrote:
? Touched up all display board connections and now I get two lines on the right side of the display. ?Mostly symbols and 8s and 9s. ?I can use the rate push to select all 9s hoping to
hear WWV but no joy. ?I can find some cw signals that sound good but no sure where they are. ?Some SSB but hard to tune in. ?
Progress but as still some work to do.
Jim w0nkn
On Apr 7, 2025, at 10:28?PM, james jones <j2@...> wrote:
?Just finished my QMX+ and really enjoyed the build. ?Built a QDX a couple of years ago and it has been great.
Powered up at 9 volts and no smoke! ?Draws about 100 ma and audio out can be controlled and tune appears to work and mode / band does something. ?Connecting an antenna increases the noise so it appears the receiver is working.
But nothing appears on the display except for the backlight. ?Turned the pot from stop to stop with no results. ?
I’m going to touch up all 16 of the display header pins. ?What a bad place for a soon to be 83 year old duffer to be soldering. ?Why couldn’t that bave been added to the display board before mounting?
Any other thots?
72/73
Jim w0nkn
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Re: Startup issues with QCX Mini (Rev. 3)
Hi Ron, Great advice! I resoldered all of the pins on all of the headers and that resolved the problem. Everything seems to be working. I’m hearing signals and putting out about 2 watts. I know I can twiddle with the toroids to try to increase it, but I really struggled to squeeze it into the case and don’t want to take it out unless I absolutely have to. And 2 watts is plenty, anyway! Tnx and 73, Rich?
Thanks, Ron. I’ll definitely start there. Tnx & 73, Rich Hi Rich, since this is a new build I think the best first thing to do is verify good solid connections especially between the control board and main board and between the display board and main board. This male pins need plenty of heat as they are fairly large. The socket leads aren’t quite as heat absorbing. Since you mention both control issues and display issues that is definitely the best place to start. Good luck. 73….Ron Hi all,
I've just finished building a QCX Mini (Rev 3; software version 1.09a; 30-meter version). When I powered it up for the first time, I got the intro screen followed by a 160-meter frequency. Having read the advice to do a factory reset if I didn't get a band select screen, I attempted to do that, and that's when my problems began. First, going to option 7 (other) and then heading for option 17, I found that the menu options stopped at around 9. Then, once I tried to move past that point, the display either went blank (still fully lit but no info) or started producing gibberish. After cycling the power several times (and waiting 30 seconds or longer before powering up again) trying to "get lucky," the display now goes to gibberish after option 4 or 5 on the main menu. Any thoughts on what the issue might be and/or how to try to resolve it? Many thanks in advance.
73,
Rich, W2VU
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I have two questions.?
I purchased a mic kit from QRP Guys.?
If I understand the QMX & QRP Guys instructions
the jumper should go straight for the QMX’s not the cross on the PCB board.?
Second has anyone found a wind screen for this mic barrel. I have not had any luck at all. They are either much to large or small. ?
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TIA
Larry NA0F ?
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Re: QMX+ T507 winding direction?
On Wed, Apr 9, 2025 at 09:15 AM, va3rr wrote:
There is some small interaction between the two windings on a binocular core which ultimately limits the directivity of the coupler, but it is not at all an issue for the QMX.
I believe that the largest contribution to imperfect directivity is capacitive coupling between the thru and coupled windings, causing VSWR readings to increase at higher frequencies despite having a good termination.
On my list is to find a small-enough miniature coaxial cable and replace the plain wire thru winding with an electrostatically-shielded one.? This should flatten out the VSWR readings be eliminating the capacitive leakage.? IIRC this has been done and reported on this forum.
73, Don N2VGU
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Thank you Stan.
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I checked everything again but was not able to find anything wrong connectivity wise.
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I ended up powering up first power board (PCB#1) disconnected:
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"V_IN": 7.0V <-- fed from lab PSU; I get 400+ mA immediately!
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"+12V": 6.8V
"VCC": 6.0V
"PWM_5V": 5.6V
"ADC_5V": 3.0V
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Is this invalid way to test it?
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Re: Does the QMX need a mic preamp? #qmx #QMXplus #SSB Firmware beta 1_01_003 release
#qmx
#QMXplus
#ssb
That chip requires 3-6ma at 2.7-5.5V.? You are not going to get that with 3.3V behind 2K. ?
No schematic handy to see what that circuit could source if you lowered the resistance.?
Might be best to stick with your batteries or find another place to source the voltage.??
Or use the recommended mic cartridge, which does not require a preamp.
73, Don N2VGU
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Re: VARA Rise/Fall Threshold Changes Affect JS8?
I set mine up for vara when my kx3 was down. I never changed it and use it on ft8 and js8call weekly with no issues.?
On Tue, Apr 8, 2025 at 9:52?PM KJ7RBS (Jadon) via <jadonerenda= [email protected]> wrote: Yes, I have run FT8 and JS8-Call successfully as well with those settings.
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The rise and fall settings had something to do with correcting the double flash low audio error code. I do not know what if any optimizations can be made to those values.
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FT8 and JS8 tone times are slow enough it should work fine with min samples at default. I had to decrease the value so the fastest VARA FSK mode would properly modulate.
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I do not know if there is another way to set parameters.
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I believe the settings are stored in non-volatile memory, so you only need to set them once. I have not had need to change the settings from the ones I found to work well for VARA so it's been set it and forget it with my QDX (I do need to adjust the per band audio levels a bit more but that's on receive)
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Cheers
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- Jadon
KJ7RBS
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I'm selling my QMX (Low Band). ?
(80, 60, 40, 30 and 20 meter bands) Built for 12 volts but I have never supplied more than a little above 9 volts to it. I purchased it as a kit and after not being able to complete the first continuity test, I sent it to W1NC Jeff Moore who finished the build. ?It’s in excellent condition and I have used it in the shack and on a few POTA activations. ?I am including a printed copy of the manual. ?Also included is the GPS kit, assembled, which works very well. I’m selling because I recently added the QMX+ to my collection.
Price is $135 which includes shipping to USA via priority mail. ?Sold as is. No returns and no warranty is expressed or implied.?
Payment via Venmo or PayPal to my email address which is up to date on QRZ.com.
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73
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N2JHR
--Jim Rusert
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Re: #qmx #SSB Firmware beta 1_01_003 release
#qmx
#ssb
Ludwig and Stan - Thanks for the suggestion on the possible cause.? Looking at the diagnostics screen, the QMX+ is reporting 10.8v for the transmitter when in receive mode and drops to around 10.0v when you engage transmit.?
Given that I fried one of the BS170s in the PA doing the SSB calibration, It is possible that Q507 was also damaged.
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--
Steve KA0SM
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N4REE - Bob
Marek SP9TKW
Donald S Brant Jr
Jim Rusert