After a few days of work I completed my new QRP-Labs Xcvr after having built several years ago a Hi Band QDX.
It was a real pleasure, no surprise due to an excellent manual and the adjustement and alignment were done today without dificulty.
Next step will be to connect it to my Alexloop antenna.
To be sure the 6 aft connectors whould slide nicely into the holes of the back plate I had screwed this plate to the lower enclosure and slid the main PCB each time I added a connector to check its position before finishing to solder it.
The first difficulties I faced were to  fit the LCD module and the front panel PCB to the Front panel of the enclosure : I had to cut slightly the nylon nut close to the potentiometer and I could not put in place the other nylon nut close to the encoder, I just left it near the hole in order to keep the good distance between the LCD board and the front PCB.
The Last difficulties happened when I wanted to slid the main PCB inside the enclosure after having put in place the four 12MM spacers which hold the dev kit, the nylon screws below did not slide easily and I had to push quite strongly the PCB inside the enclosure.
WELL I'M HAPPY WITH THIS WONDERFUL KIT AND I'M GRATEFUL TO HANS FOR THIS NICE DESIGN.
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Re: New QMX+ Calibration victim
Hi Stan,
Thanks, You were right. Lifting input legs of IC503 cleaned up the output from IC501/502. So new order to Mouser... :-)
Jonas,
It is very uncommon for IC501/IC502 to fail, but quite common for IC503 to fail with blown finals.
So I would first lift a leg of IC503 that connects to the output of IC501 or IC502, and make sure it is not some failure in IC503 that causes the IC501/IC502 outputs to look bad.? Failures in ICs can affect their inputs as well as their outputs.
Stan KC7XE_
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Hi Tony
I just measured one of the 1N4007 diodes from the kits, the wire diameter is 0.4mm. According to the PCB CAD program (I just checked) the footprint for these diodes specifies a 0.8mm drill size. So the holes ought to fit 0.7mm wire too.?
On Fri, May 23, 2025 at 5:07?AM mux_folder2001 via <canthony15= [email protected]> wrote:
Nothing fancy on these connections. Top layer and bottom layer traces only. I just checked with the meter and all is well. My question really was about the diodes. Where do you get 1n4007 diodes with .3mm leads?
Tony
AD0VC
Tony,
?
The QMX series of radios uses a 6-layer PCB. Making the drilling hole larger could cause gaps in the internal layers. It would be better to use a thin lead and solder the fat lead above the board. Look at the board trace pictures and the schematics to
verify that the connections are still there.
?
73
Evan
AC9TU
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QRP Labs kit shipping status
Hi all
Well I got back to Dayton and after some work to release my suitcases full of electronics, which were impounded by customs at our local airport, all is well. I have a large backlog of sleep and emails to catch up on, as well as the jet lag...?
Since the SSB firmware beta release at the end of March, sales volume doubled compared to the normal monthly average. The waiting list for assembled radios also doubled (see attached?chart which includes Dayton booth orders for assembled transceivers). Unfortunately I am informed by my colleagues that some kits have run out before the new batches?arrived. It takes several months to arrange manufacturing of a batch of 1,000 QMX or QMX+ kits, including component procurement from various parts of the planet, PCB manufacture and SMD assembly, preparing the kits of through-hole parts etc. It's a little difficult to judge the timing exactly.
So: - QMX: no stock. All through hole parts are either on hand, or on the way. The PCB assembly is completed and just pending shipment. All QMX kit and assembled radios orders are waiting for this new batch of QMX boards to arrive.?
- QLG3 GPS: no stock. There was an unexpected lead time on the E108 module but they were delivered yesterday. Now pending the SMD factory to assemble the boards, they will be shipped (along with lots of other board batches I ordered). Any QMX+ orders that include the QLG3 option are pending the arrival of the new batch of QLG3 boards.?
I updated the shipping status page:?
We have several other kits that are low on stock (including QMX+) but the new boards and parts are expected to arrive before the stock reaches zero.?
Thank you for your continued support.
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Re: 50 Watt Power Amplifier - Low Power, High Harmonics
#50w
#50wpa
Probably time to work progressively through the amplifier path starting at the input and a hopefully clean input signal?
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Re: 50 Watt Power Amplifier - Low Power, High Harmonics
#50w
#50wpa
On Fri, May 23, 2025, at 12:09 AM, <wtshyman@...> wrote:
I also found the discussion with KO1KR in August of 2020, but unfortunately I can't see his scope photos so I don't know if he had the same problem
Hi Bill,
?
Groups.io deletes photos posted directly into the post after a given time, which I believe is 30 days.? I save all of the original posts in my email archive to get around the deletion.? I searched that archive for KO1KR and found no posts for that callsign.? I also looked in QRZ and did not find a callsign.? Is that a typo?
?
It has been a few years since I played with the 50w amp.? I believe that I had to reduce the voltage to my QDX so as not to overdrive it, which does not explain the low power output.
?
If you can give me the message number, I can look up the photos you want.
?
73
Evan
AC9TU
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Re: QMX+: low RX sensitifity @ 6m / 22 dB noise floor / 1500 Hz wistle
Hello Ken,
?
I am also skeptical about my cure and therefore I made several measurements to find sources of noise and constant tones of my QMX+.
?
In post #144992 I show the Lo signal @6m with strong sidebands (lines) around strong LO signal.
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The LO signal was detetected connecting the BNC of QMX+ to a spectrum analyser (LibreVNA operating in spectrum-analyser mode, QMX+ in RX, DIGI mode)
LO signal is 12 kHz below RX frequency.
?
Another OM with same QMX problems verfied my obseraton (sidebands around LO signal) using a SDR RX and waterfall diagram.
?
After resoldering trifilar and handling PCB strong sidebands are gone but 1500 Hz tone remains, and I am happy QMX is working, but I am unhappy that I find no cause (QMX is working at lower bands).
?
In meantime I tried o understand detection technique of QMX (Tayloe detector)and to find a method to quantify signal strength of tones and make it reproduceable using wsjtx.
?
Measurements are on-going and I will post my results in next time.
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@all: Can anyone with RX problems (high noise and addtional tones at higher bands) verify my observations of sidebands around LO signal?
???????????????? - Switch QMX in RX only mode, connect BNC to another RIG and observe spectrum 50 kHz around
???????????????? RX frequency (e.g. SDR and waterfall diagram).
??????????????? - Signal strength is between -40dBm - -130 dBm.
??????????????? - Please report additional signal strength in wsjtx (dB indicator at main page of program)
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Vy 73 Michael
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Re: Tune SWR on QMX+ always shows SWR <1.05
The release software now has a CAT command to read the SWR value, and extra virtual serial ports, so everything is there that is needed on the QMX side to make this happen - good luck, and let us know how it goes.
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Cool! I was hoping there was a cat command like that - I suppose the most difficult thing would be for the esp32 to "host"/manage the serial connection, but it should be possible :)
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On Thu, May 22, 2025 at 05:00 AM, Rick Hill wrote:
The audio levels are painfully loud when adjusted for correct usb output to WSJT-X.
I think I understand what you are saying, and the need for an audio change - but I think the words you used are not quite accurate.
Adjusting the USB level for WSJT-x doesn't (or shouldn't) affect the audio level out the earphone/headphone jack.? They are separate audio paths.
So I think the reason the headphone audio level for digi mode is very high is for a different reason.
I believe it is because the way you set filters/AGC for CW mode (and SSB) requires you to turn the audio gain higher to get the appropriate CW audio level - and that makes the audio level in Digi mode higher.?
Since digi mode is not affected by the AGC, this makes it comparatively very loud.
?
I don't experience this problem with my setup, perhaps because I use different AGC settings (something close to the default), and don't often listen to weak CW signals for which I turn up the volume.
Does this sound like it could describe what you are experiencing?
?
If so, yes, I agree that adding a capability to silence the headphone audio for just digi mode would be useful.
Stan KC7XE
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Re: New QMX - observations and best QSO
You need a 12V USBC-PD 'trigger' cable with 5.5/2.1 connector, such as this one:
There are similar cables for 9V if you build your QMX for 9V.
And I use a similar power bank by Anker that is even smaller, but costs a few dollars more:
I use this one:
The 10,000mAh capacity gives me a few hours of operation time.
Stan KC7XE
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Re: New QMX - observations and best QSO
Congratulations! Which power pack did you buy. I found an INIU 10000 mah power pack with 12 volts out on Amazon, but it only has a usb-c output. I don¡¯t understand how it can be hooked up to a QMX. Wat am I missing? ?Thanks.?
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Re: Introducing QMX CARROT
It's the small QMX for 60 to 15 meters.
The case and accessories aren't available from QRP Labs (yet ... just kidding).
73 Chris
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50 Watt Power Amplifier - Low Power, High Harmonics
#50w
#50wpa
Hello. I'm assembling a 50 watt power amplifier for use with a QCX+ that I assembled last month, for the 80 metre band. I have very high harmonics at the output of T3 - as a result, I get only about 9.3 watts out when running at 13.8 V.
Output from the LPF looks OK on the 'scope.
I found the excellent videos by NA5Y which shows the output of T3 should be much closer to a sinusoid than what I get. I also found the discussion with KO1KR in August of 2020, but unfortunately I can't see his scope photos so I don't know if he had the same problem. I've since skimmed through the many discussions on this forum but haven't found the same issue exactly, though I did check out some of the suggestions given here.
I found the amplifier took 67 mA with R5 fully CCW - I adjusted R5 till the amplifier drew about 70 mA with the QCX+ key-down in practice mode.
Here are my scope traces: 0092 is the gate drive, yellow is Q1 gate, purple is Q2 gate - all is well here. 0090 is the drain voltage, Q1 in yellow and Q2 in purple - these look like there is oscillation ? 0091 is the voltage at the output of T3. This has a lot of third harmonic and doesn't look like the waveform NA5Y showed at this point. (QCX+ was set for 3.520 MHZ , amplifier connected to a dummy load.)
I thought that perhaps my bench power supply is doing something odd when the amp is drawing power, but I probed the 12 volt line right at the barrel connector and the 'scope showed almost no disturbance of the +12 v supply.
In frustration, I observed the output of T3 with the 'scope set for a long capture - it almost looks as if the distortion grows with time, for the first few tens of microsceconds the scope showed a small but sine-ish waveform, which over the span of a few hundred microseconds got wigglier and wigglier till it developed into the mess seen in my scope capture 0091.
I've checked DC continuity to the windings of all the transformers and coils. I did find a bad joint on the primary of T1 but I cleaned it up and can now get power out of the amplifier.
I haven't yet checked bias on all the 1N4007 diodes but the input looks quite sinusoidal at R3 closest to the input. The few watts the amplifier does produce look OK at its output. The QCX+ makes about 4.3 wats into a dummy load (43 V peak to peak) at 13.8 V DC.
I'm assembling these units for a friend, and I had really hoped to have them ready for Field Day this year. The instructions are excellent and I have followed them closely.
What can I look at next?
Bill VE4STW
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Re: Mini Microphones for QMX SSB
When you click reply, if you select "Sender" instead of "Group" below my name, it will send just a private email to me instead of to the whole group. Unless you want to tell everyone you want to order a mic.. :)
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Erik AD7OV
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I am with you Ken..do not want to select Digi mode via the rotary encoder intentionally or unintentionally whilst switching modes.
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Re: Pop! Oops, blew a BS170 in my QMX, my fault. Lesson learned
Thanks all for the feedback!
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I received the BS170¡¯s from Digikey today and made quick work of replacing the blown one. I thought I would replace just the one and test the results.?
Luckily everything else seems fine and all diagnostics measured normal. ?Made a few ?FT8 QSO¡¯s on the QTH antenna and all is good. ?Now to tune rhe field antenna?
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Re: Why no AGC for digital modes, as other modes?
Could have AGC (or just some crude clipping) on data to the DAC for the QMX headphone jack
Jerry
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On Thu, May 22, 2025 at 06:27 PM, ajparent1/kb1gmx wrote:
or digi modes no agc helps.? Reason is that if a strong signal appears
in the pass band it pumps the agc and all signal are reduced by that
amount.? ?So a digi band has a couple of very strong signals it tends
too make the weak ones impossible to detect.? ?It was a big problem
with early receivers with a strong agc system rather than large
dynamic range.
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?described differntly AGC when it operated it does so by
making the radios gain lower to correct the excessive
level.? Good for the ears but it also is making the radio
less sensitive to accomplish that.
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--
Allison
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Texas Instruments often skips the "74" in front of the chip name, so 74ACT08 is actually what you need to look for...
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Nothing fancy on these connections. Top layer and bottom layer traces only. I just checked with the meter and all is well. My question really was about the diodes. Where do you get 1n4007 diodes with .3mm leads?
Tony
AD0VC
toggle quoted message
Show quoted text
Tony,
?
The QMX series of radios uses a 6-layer PCB. Making the drilling hole larger could cause gaps in the internal layers. It would be better to use a thin lead and solder the fat lead above the board. Look at the board trace pictures and the schematics to
verify that the connections are still there.
?
73
Evan
AC9TU
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You can either measure continuity from top to bottom, or solder both top and bottom. Whether the via is needed depends upon which or both have connections.?
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Don't think that the lead must go through the hole. It doesn't. Note all the surface mount parts without any leads (-:
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Pierre - FK8IH
Bruce Akhurst
Joe
Chris