Re: QMX+ Displayed Voltage Low
Using 13.5V is a bit risky. The QRP rigs are designed for 12V, not 13.5V like most radios, especially on transmit.
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Not yet. I thought about that last night and will take that measurement today. For additional testing, I hooked
up a constant voltage power supply to my QMX+ last night to get some measurements. When I have the?
constant voltage power supply set to 13.5 volts, my QMX+ reads 12 volts and produces good power output
on 20 meters (3.5 watts). I have not checked the other bands yet. I suspect that the open circuit voltage of
the diode string is higher than the loaded voltage and thus the power is dropping a lot farther than expected.
The plan is to modify the diode string to provide 13.5 volts under load in order to mimic what I did with the?
constant voltage power supply.
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I was able to make 2 contacts on 20 meters last night with my QMX+. One in PA and the other in TX from my
QTH in Boone, NC. Pretty excited that I was able to drive enough power into my primary antenna system to
make those contacts. I normally run a 200 foot dipole with 450 ohm ladder line tied into a symmetric PI-network
tuner for impedance matching.
Thanks for the response.
?
Cheers and 73s
--Corey(WB0RXQ)
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Paul - just picking up on a few days ago.? You pics don't appear very large on here but these are a few that caught my eye.? It may be the light and They may of course be functionally fine but I'd be working around anything that doesn't look like a perfect joint without splatter etc.? at this stage as well as searching the top of the board for stray wires and blobs.? As to the soldering - adding more solder isn't always the best way.? Adding a blob of no-clean re-work flux often improves the look of a joint quicker as does following the rule of heating the two bodies of metal for what experience says is enough time (often several seconds for large prongs and groundplanes)? before adding the multicore solder?
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Re: QMX+ Displayed Voltage Low
What about using a LDO like LM2940-12? The voltage-drop is only 500mV @ 0.8A and it limits to 12V do you don't exeed the maximum voltage for the QMX+.
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Re: New QMX Midband built
On Tue, Jul 16, 2024 at 05:42 PM, Andreas K6AKW wrote:
I didn't make any changes. I just cycled through the different bands a few times. All of a sudden the results for 60m came out OK. So it's probably a software issue.
Andreas, sometimes ago I had similar effects. For me after a Factory reset the sweeps were ok and after a while working with the QMX I had strange results again but no bad effects on the receiving. No real solution until now.
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73 Ludwig
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Re: New QMX Midband built
And now I am back to the bad results again:
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Again, no changes. Just ran a few sweeps (Audio filter, RF filter, etc.) then back to the Image sweep. So what we see in these sweeps can't really be taken at face value all the time. There seems to be a certain amount of randomness.
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73, Andreas
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Re: QMX New build - no flash drive - how to troubleshoot?
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Thank you! re: Regarding the second point voltage at "+12V" should come up after PWR_ON goes down I will double check this tonight & report back. Regards! ~Gordon Sent with Proton Mail secure email. On Tuesday, July 16th, 2024 at 3:37 AM, DH8WN@... <DH8WN@...> wrote: On Tue, Jul 16, 2024 at 01:46 AM, Gordon Young wrote:
so far I get
- correct BAT_LEVEL value
- PWR_ON pulled down when left encoder depressed
no 3.3 volts present at ?LIN_REG_EN
when depressing the left rotary encoder the voltage at LIN_REG_EN goes to .75 3/4 of a volt but never 3.3 regardless of BATT input voltage. Gordon,
please follow the description in the Wiki document. Regarding the second point voltage at "+12V" should come up after PWR_ON goes down. Without this voltage nothing will work.
Did you solder both sides of the female pin header to the SMPS subboards?
73, Ludwig
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Re: New QMX Midband built
I also just noticed that the results are not always reproducible. I just did an image sweep on 60m and now it looks OK:
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I didn't make any changes. I just cycled through the different bands a few times. All of a sudden the results for 60m came out OK. So it's probably a software issue.
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73,
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Andreas
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Re: New QMX Midband built
Hi Ludwig,
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thanks for the reply! Results for 40m are excellent:
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73, Andreas
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Re: QMX+ Power Increasing Question
Thanks for the reply Hans. I have posted on another thread that I have it sorted. I did as you mentioned, and moved the turns on the LPF toroids,that improved it by about 3dB. I then removed one turn from both toroids and now have over 3W on 6m. Infact after a little tweaking I now have over 3W on all bands which I am happy with. I have a Marconi digital power meter with a 10GHz head, along with a 30dB power pad mW translates directly to Watts. The power I read on the Marconi correlates very well with the power meter in the QMX+.?
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Thanks for all your time and effort developing this lovely little rig. Looking forward to getting the updated firmware for other modes. BTW, I'm impressed with the CW reader, although CW has long since left my brain!!
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73 de Dave G4FAW?
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Re: QMX Hi-Band: DELIGHTED!
This was my finding also.? I started with a qcx, then a qcx mini. Then a qdx followed by another qcx mini and finally the qmx with another on the way.?
I had two issues that were nothing to do with either the build or the performance of the units.? Firstly I blew the finals on the qdx by transmitting into an antenna that wasn't actually connected to the radio....? and secondly the power output on one band on the qdx was a little low. A bit of advice from some on here and a little fiddling with one toroid winding and it's all into place and working fine. I've used all my qrp-labs kits out portable and made many hundreds of contacts on them.? The build manuals and thought that has gone into these kits is beyond anything I have experienced from anywhere else.?
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I think the qmx is definitely not a beginner kit. Although you are dealing with all through hole components,? everything is very cramped and the six layer board needs some decent experience with a soldering iron. That said the manual is so detailed,? I'm sure with patients and decent workshop rabbits anyone with a steady enough hand and a strong magnifying glass could make this kit work.?
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Re: QMX shows 3v3 SMPs board stuck in linear
Dear Robbie,
I was building a QMX+ and I had the same indications on my power supplies.?
I think I have an intermittent short on my board but can't seem to find it ... Eventually the little transistors on the left side of the board
starting getting hot.... Now it no WORK at all...
Here is my diagnostic chart:?? It looks just like yours.
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Re: QMX+ Rev1 Build Report
On Tue, Jul 16, 2024 at 08:57 AM, Randy wrote:
I use my fingers to push and flatten the wire against the edges and outside of the toroid and the screwdriver to flatten the inside.
My new favorite tool for doing this is one of the ~6mm bamboo skewers, the end opposite the conical point being carved into a blunt screwdriver shape, like the old orangewood "spudgers".
The cone end is used for inside the toroid, the screwdriver end for outside.? This eliminates nicking the enamel or copper with a metal tool.
It is also useful for holding the turns in place when taking a break, by impaling the toroid on the cone.
I also use plastic crochet hooks for pulling wire through tight places.
73, Don N2VGU
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Briskly reading through the group one might think every build is fraught with problems. Not so.
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My kit build was intentionally slow and cautious, and I've kept an eye on this group, learning many things along the way. The only new tool I bought for this build was a 10x loupe, which came in very handy.
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My interest is primarily CW, so I haven't tried any of the digi modes. Nor, have I done any extensive filter torroid tuning. Built exactly to the manual, I see these power outputs, measured with a ?into a dummy load, and power draws measured by my bench supply. Input voltage: 11.7 from a in the power line. BTW, idle power draw is 0.125 A.
| 20M – 14Mhz |
4.06 watts |
0.582 A |
| 17M – 18 Mhz |
5.61 watts |
0.797 A |
| 15M – 21 Mhz |
5.64 watts |
0.903 A |
| 12M – 24 Mhz |
3.93 watts |
0.743 A |
| 11M – 27 Mhz |
4.05 watts |
0.772 A |
| 10M – 28 Mhz |
3.63 watts |
0.718 A |
Beyond these early measurements, I quickly made a handful of QSOs as I hunt POTA operators, and enjoy the ease of operating this tiny radio. I don't yet feel compelled to do any torroid tweaking. I continue to be amazed at the physical engineering, at how Hans managed to pack so much into such a tiny space, and at how much configurability the 1.00_020 firmware offers.
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So, while this group is mostly used for troubleshooting (all of which I thoroughly appreciate) I offer my note of success as encouragement for those still building. I'm absolutely delighted with what Hans has brought us and with all the information this group's participants bring.?
THANK YOU!
--
72 de N4REE, Bob Easton - QRP CW forever
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Re: QMX+ Displayed Voltage Low
I just daisy chained 6 1N400 diodes together to drop the open circuit voltage down to 11.75 volts. Most
likely this was a huge mistake as the loaded circuit voltage is probably a lot less than 11.75 volts. I'm going
to experiment with the loaded voltage readings today on different points on the diode chain and find the
correct voltage to drive the QMX+.
?
Cheers and 73s
--Corey (WB0RXQ)
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Re: QMX+ Displayed Voltage Low
Not yet. I thought about that last night and will take that measurement today. For additional testing, I hooked
up a constant voltage power supply to my QMX+ last night to get some measurements. When I have the?
constant voltage power supply set to 13.5 volts, my QMX+ reads 12 volts and produces good power output
on 20 meters (3.5 watts). I have not checked the other bands yet. I suspect that the open circuit voltage of
the diode string is higher than the loaded voltage and thus the power is dropping a lot farther than expected.
The plan is to modify the diode string to provide 13.5 volts under load in order to mimic what I did with the?
constant voltage power supply.
?
I was able to make 2 contacts on 20 meters last night with my QMX+. One in PA and the other in TX from my
QTH in Boone, NC. Pretty excited that I was able to drive enough power into my primary antenna system to
make those contacts. I normally run a 200 foot dipole with 450 ohm ladder line tied into a symmetric PI-network
tuner for impedance matching.
Thanks for the response.
?
Cheers and 73s
--Corey(WB0RXQ)
|
Re: QMX mid band 60m reassignment
Seems the only option for the 60M slot is 80M, and I would question what you could practically do on 80 with QRP.? No doubt someone has worked DXCC or some similar amazing feat on 80M QRP but in my decades of portable operating, 80M has never been a consideration nor an interest.? So much more low hanging fruit on 40 and up.? Probably the best of all worlds would be a 40 through 10M QMX, a mix of the mid and high band QMX's.? I haven't worked a lot on 10 either, even though we're coming up on the peak of the cycle.? So at least from my portable operating perspective (I don't use QRP much from the home station) the QMX mid band checks all the prime band boxes.? I've watched and waited until this specific QMX became available before jumping in, knowing this was the sweet spot.? Anything you would ever want to work, with antennas you can practically string up in the field, can be done 40-15M.??
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Mark K5LXP
Albuquerque, NM
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Re: QMX+ Rev1 Build Report
M0WAS,
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Here is a photo of the toroids. The number of turns on each is by the instructions, and they are spaced fairly evenly on all. I haven't tried to optimize anything yet and not sure if I will.
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My winding method is more threading and bending the wire around the toroid so that it lays flat as possible against all surfaces including the edges, the inside and outside. I use my fingers, a magnifier and a jeweler's screwdriver to make sure the wire is pushed flat and touching the core on the inside. Sometimes the first full winding (bend) is hard to get tight, so I leave a little extra wire length to unwind the first turn (which could be loose) and then make it up at the end. To clarify, I use my fingers to push and flatten the wire against the edges and outside of the toroid and the screwdriver to flatten the inside. Perhaps not the easiest way, but it works for me. Over the years I picked up some speed and can do it fairly quickly.
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I take a lot of time to scrape and tin the leads as close to the toroid as possible and still leave a little insulation, and it is very time consuming. Before soldering it to the board I check the core color and verify the number of turns one last time. You may see a different color wire on some of my toroids. I do this for contrast to make the turns easier to count. When I mount the toroid on the board, I try to make the leads as neat and short as possible with no over lapping windings. Sometimes it takes a number trys to get it looking right. I use Kester flux 245 .031 dia. solder with an older (2003/4 vintage) Hakko 936 station and many different size tips. I hope this info helps.
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72,
Randy NR5N
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I will.
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--
Allison
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Post online only,?
direct email will go to a bit bucket.
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Re: QMX+ Rev1 Build Report
I meant to say that I removed and replaced Q103 with a spare D403 device. Sorry for the confusion.
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72,
Randy NR5N
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Hi remind me never to talk to you again!
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Bruce Akhurst
Gordon Young
Donald S Brant Jr
N4REE - Bob
William C Brown
Andrew Lenton