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Re: Handheld QMX?
This is the golden age of electronic experimentation.
I can design a PCB in Kicad and have 5 boards built and delivered in a week or two for $5.
Parts for a complete transceiver similar to the Micro-mountaineer can be found online?
for a grand total of maybe $10, along with all the needed datasheets.
A $15 RPi-Zero would run circles around a million dollar Cray 1 for DSP algorithms.
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Communications is no longer problematic in an era of cell phones and email, radio isn't quite so magical.
Many of the experimenters have moved on to DIY audio, electric vehicles, robotics, off-grid power.?
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The big thing in RF power amps these days is Current Mode Class D, or CMCD.
This is considered a further development beyond Class E or Class F, and the subject of numerous MS and PHd theses.
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Curiously enough, it's the AM phone crowd doing much of the experimentation with DIY builds in ham radio.
A CMCD type RF amp with a Class D AM modulator could be easily adapted for use with Hans' Synthesized EER scheme.
The INN650D02's mentioned by KJ7AGO in that final web link above are $1 on Aliexpress, I've got 20 getting shipped this way.
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Around 1970, an aging ham gifted me with his junk box.
Included some Ford coils with which to build a spark gap transmitter.
(Scary to think that he was younger than I am now.)
Also a 2kv 2kW plate transformer and a couple dozen 810 triodes.
Still have the 810's down in the basement, and occasionally consider building this push-pull amp:
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Curiously, that 810 design from 1938 has the topology of a Current Mode Class D amplifier.
There are published examples of that design dating back to about 1930.
This 1934 guide for amateurs has many different CMCD style designs.
Those guys knew what worked, and I'm sure they fiddled with drive levels and? tank circuit C,L values
till they got maximum efficiency.? ?Which would put it in CMCD mode with ZVS.
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Jerry, KE7ER
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On Sat, Feb 22, 2025 at 07:38 AM, bill K7WXW wrote:
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Re: No special characters to delete messages?
Chris, reading the firmware release notes, I see that message editing from the menu was broken in firmware versions 24 and 25, and is fixed in the current version. So you will need to update firmware, or edit the messages using the terminal program.
Stan KC7XE? |
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Re: My new QMX+
#QMXplus
On Sat, Feb 22, 2025 at 09:12 AM, Mark Flavin wrote:
You can do this yourself by disabling the unwanted bands in the band configuration screen, then modify the filters and filter selections to be specific to the bands you want. |
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Re: My new QMX+
#QMXplus
Agreed.? I think making a option for say 160-20 of 40-10m or 6m would be nice.? Then maybe ea. filter only has to cover 2 bands
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Mark N5MF |
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Re: My new QMX+
#QMXplus
Mark,
?I have had the same problem trying to get 20, 17, & 15 m to peak up in power. Whenever you get one band up, the others are down. I don't think there's a good solution, but it's well under 1/2 S unit down, so I don't think it's a big problem. Be nice if there was an extra LPF so you only have to get 2 bands with each LPF.?
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73, Dan? NM3A |
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No special characters to delete messages?
Hello Everyone,
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I just fired up my QMX with Firmware version 1.00_025 and tried to edit the message memory.
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Adding characters works fine (via tune nob as well as vis CW keyer). However, while using the tune nob I can't see any of the special characters (Insert, Backspace, Delete. etc.).
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Is there some hidden option in the menu to enable them?
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Thanks and 73
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Chris PY2GUT? |
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QMX SMPS issues, and a possible cure
I'd like to know the firmware and hardware rev from anybody who has trouble with the QMX 3.3 and 5.0v power supplies.
Mostly, I'd like to know how often these failures occur with the most recent firmware and hardware.
If that gets noted here in the forum, the pressure increases to find a more robust solution.
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Symptoms might be a bad diode at D108 or D109, a fried processor, fails to work after jiggling the power connector,
fails to work after accidentally shorting a power supply with a probe, fails to work after multiple short power button presses.
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As I previously reported, I have some linear regulators on a one inch square scrap of vector board that plugs into JP105,
this seems to work well after some minor mods to the QMX.? Specifically, need to lift the drain lead of Q106 and Q107 to
disable the old SMPS's, need to add 200k in parallel with R112 and R113 so the firmware thinks it's seeing a bit more than
3.3v and 5v (it hangs if it sees a wee bit less) and short drain to source across Q111 so the 3.3v linear can drive ADC_3V3.
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I'd prefer that Hans change the firmware such that at power up it first checks if LIN_REG_EN is low, and if so skips all the
SMPS start up and voltage checks.? Then the only mod to the QMX would be to add a 10k resistor from LIN_REG_EN to ground.
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I don't encourage others to repeat my efforts at this time unless this is simply something you enjoy doing.
Odds of blowing up your QMX are greater with my mods and hacks than they are with the old SMPS's.
Success is not guaranteed.? Reports of SMPS failures are no longer very frequent with Hans' latest firmware,
especially given that there are?thousands of QMX's in operation.??
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As Hans has said, there are many different kinds of failures being reported in the forum.? The majority are due
to bad soldering, especially around attempts to burn the enamel off of the magnet wire.? Fortunately, most?
failures are easy to repair.? Unfortunately, an SMPS failure often blows the 100 pin STM32F446 processor.
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I feel that the primary issue with the old SMPS's is that the voltage gets checked by the processor only once
every millisecond or so.? That's fine if everything works as it normally does, but something unusual can?
upset things faster than the processor can react.? For example, if the 5v rail is momentarily shorted to ground
by a scope probe, the processor might increase current to maintain 5.0v but not react fast enough when the
short goes away.? Designing an SMPS from scratch (or in firmware) is a difficult exercise in control system theory.
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I just received my Kicad PCB fab for a one inch square board to replace my linear regulator vector board.
This design has a couple SOT23-6 SMPS IC's.? There's a huge number of different parts from different venders to choose from.
Max current varies from 500ma to 2A. They operate at frequencies varying from 0.5 MHz to 2.2 Mhz.? Cost can be as little at $0.10.
Provision is made to allow the board to be fully shielded using cheap copper foil, held up by L shaped header pins.
I am designing for the cheapest SMPS IC's which operate at an internally determined frequency, more expensive part
(still under $1) can be driven by an external clock source such as a processor PWM pin to eliminate any birdies.
The board can be separately built and fully checked out, including how it behaves with an intermittent or varying Vin, momentarily
shorted outputs, momentary low current demand, and changes in temperature.? It could be temporarily plugged into header pins
at JP105 of the QMX, or permanently soldered in place to those header pins.? If plugged in, I would recommend adding a
soldered wire connection for ground, since if that flakes out momentarily it could be disastrous for the QMX. ?
If it's successful, perhaps we of the forum can make it available as a kit.?
Or perhaps Hans would like to add it to his shop for purchase.
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Jerry, KE7ER
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I started this thread in response to this post ?/g/QRPLabs/message/139515
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Re: QMX+ shutdown problem
On Sat, Feb 22, 2025 at 04:10 AM, Kevin (KQ4DTX) wrote:
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Re: Handheld QMX?
开云体育And here I always thought those dual gate FETs were 40673’s. ?Ahh, the good old days when parts were visible and the part numbers could be read by the unaided eye.Dave On Feb 22, 2025, at 10:38, bill K7WXW via groups.io <K7WXW@...> wrote:
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Re: My new QMX+
#QMXplus
Hey Mark,
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Congratulations on your successful build!
My QMX+ also produced very silimlar output. Yours being slightly better results.
I built mine for 9v and posted my results a few days back. The general consensus seems to be that those are typical expected values.
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Cheers?
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Mel. M0KMD. |
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Re: Handheld QMX?
I don’t know, Jerry, maybe not the norm, but a significant proportion of hams built their own gear back then. “Solid state design for the radio amateur” sold more than 50,000 copies, the ARRL handbook was filled with practical projects and a reasonable amount of electronic and RF theory, and there were still lots of local places to buy parts. I was a digital design engineer in those days, and did RF stuff when I got tired of zeros and ones.
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Or maybe my nostalgia for the golden years of DIY PCBs, ECL and 40763s, leaded components, and deadbugging continue to get the better of me. :)
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bill K7WXW |
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Re: My best practice for part inventory
Great idea using the foam board.
toggle quoted message
Show quoted text
I do something similar when winding toroids in that I lightly tape them down with some painters tape on a stiff piece of a manila file folder. I write the particulars of the part identifier and turns next to each one. I wind all the toroids and transformers in one or two sessions checking turns and evenly spacing by eye.? Then I test fit before removing the enamel, clip the leads about 1.5cm long from the bottom before removing them from the PCB to? remove the enamel using the 'drag through a solder blob technique' and then complete the installs.? Zero toroid problems on 5 Qs and 3 50W amp builds so far.? GREG
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My best practice for part inventory
YEA - just finished QMX and all diag look good - nice to have itt work 1st time - all that triple checking paid off. BUT:
Was very valuable to visual inventory and pre-sort all caps w/ a printout on foam for parts/Part# AND - I am 60 years old.. so all work was done under a MAG LIGHT -- --------------------------------------- KINETIC LABS 14850 NW Northumbria LaneBeaverton Oregon 97006 FAX: (413) 294-7223 PHONE: (503) 382-7117 spencerbarrett@... |
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My new QMX+
#QMXplus
Just wanted to say that the QMX+ was a pleasure to build and, now that I've actually read the operations manual, it seems to be working as advertised!? With the GPS finally syncing up.
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My power is pretty typical I guess but I am a bit surprised that the the 20 and 17 are so much less than the 15 meter output.? Built for 12V
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160? -? ?5.6
80? ? -? ?5.6
60? ? -? ?4.8
40? ? -? ?4.8
30? ? -? ?5.0
20? ? -? ?3.8
17? ? ?-? 3.0
15? ? ?-? 5.2
12? ? ?-? 3.1
10? ? ?-? 3.8
6? ? ? ?-? 2.5
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Everything seems to be as advertised with no issues when following instructions.? HI
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If any one has found a way to get 20 and 17 up a bit i would be interested.? seems they should be as good as 30 and 15!
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Anyway very nice project.? Hats off to Hans for another fun radio.
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Mark N5MF |
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I wound the torid in tight groups of 6x - Note the 27 turn fills up the inside of the torid. - When I verify the groups fo 6x.. it is not easy to count - but I find the middle of the 6x winding - and there are three windings to left and right.On Sat, Feb 22, 2025 at 3:54?AM David Wilcox K8WPE via <Djwilcox01=[email protected]> wrote:
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--------------------------------------- KINETIC LABS 14850 NW Northumbria LaneBeaverton Oregon 97006 FAX: (413) 294-7223 PHONE: (503) 382-7117 spencerbarrett@... |
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I GIVE UP!
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Pressing the encoder the +12V pad showed 11,5V, Vdd 0,01V and Vcc 1,15 V.
But then, possibly the DMM probe shorted the Vcc and Vdd pads of JP105...
Every voltage is now zero, the encoder pressed or not.
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I really would like to see a robust QMX++ with linear regulators. So much trouble (me and many many others) with the SMPS'es.
Remember the KISS principle!
Saving some hundred mA may be relevant if running with alkaline batteries, but most of us are using AC powered chargers or massive lithium batteries.
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73 Matti OH6BEX |
Richard Dyer
bill K7WXW
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