Tuning up your QCX+
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- čas přidán 30. 06. 2024
- How to optimize your QCX/QCX+/QCX-mini for best performance.
Applies to the whole QCX range: QCX, QCX+ and QCX-mini.
From time to time people ask about low power output, particularly on 20m and 30m versions of the radio; the video shows my tune-up, test and adjustment procedure for a 30m QCX+ with TCXO and Enclosure options. Initial power output was just 0.77W but by the time I was finished, merely by adjusting the inductors, I had 4.6W (both at 12V supply).
The video also shows the oscillator calibration (using QLG1 GPS) and the receiver alignment procedure.
Links:
QCX+ qrp-labs.com/qcxp
QCX+ shop: shop.qrp-labs.com/qcxp
Assembled QCX+ in shop: shop.qrp-labs.com/assembled
QLG1 GPS: qrp-labs.com/qlg1
Power measurement tutorial: www.qrp-labs.com/qcxp/rfpower....
Our source for micrometals toroids: kitsandparts.com/
Our source for Vishay NP0 capacitors: digikey.com
Great stuff, I am currently studying to get my license back. I let it lapse in the early nineties. I will be ordering one of your kits once licensed again.
I love this man. Absolutely love him. At 21:10, his bench is just like mine before I retired except I had a Logic Analyzer and a 4 Channel Storage Scope. I have his QCX-40 and I'm now assembling the QDX. In a few days, I'll order the QDX-mini kit.
👍Very helpful video Hans. Thanks for taking the time to do this. My 20m QCX output is about 3W, so will follow your procedure to see if I can squeeze it up to 5W (by squeezing and unsqueezing some inductors).
My workbench is a little like yours with lots of leads. Recently I got so fed up tracing which was connected to what that I spent some time labelling them.
On another note, last weekend I planned a SOTA activation. Just beforehand, I checked my FT-817 and found it was faulty with no TX output. With no time to investigate, I stuck the 20m QCX in my backpack instead. Connected to a 20m EFHW, the QCX performed flawlessly and the summit was easily activated.
hello Hans , great explanation, now I learned how to adjust my QCX 40m , thanks for the glass. just won a writing on the channel. PY1FW Leo
Notes to anyone building the QCX mini. The 16 wires that you use to solder the LCD display to it's carrier board needs some care. Pins 1 and pins 5, 6, 7, and 8 need to be soldered VERY close to the PCB. This is to avoid shorting to the ISP header and to the top of C47 after assembley. Bend those wires at 90 degrees as they come through the board and solder them without adding any extra height. the tolerances in this kit are insane, but very much worth it. Compared to my first transmitter kit, the Howes CTX80, this kit is off the scale in terms of conception, design, realization and execution. Very well done Hans and to all at QRP Labs...
Very nice and informative video. Nice production style too. Love that there is no long intro and no corny background music - just good information.
All technology and science at their highest levels becomes art.
*Thank You Hans* 😊💙
This will come in very handy very soon as I have just begun my 30m QCX+ build.
Detailed, just like the build instructions. Thanks Hans!
Very informative - thank you! I was pretty happy with 4.8w on 40m #2175, but decided to go through all the steps in the video and managed to get another watt @ 14.4v.
Excellent video instruction. Easy to follow. My QCX went from 1.1 W to 4.3 W at 12 V in 15 min!
Thank you Hans for putting this video together. I just went from 32.8V Pk-Pk to 40.8V Pk-Pk with my 20m QCX. I also calibrated the oscillator with my station clock/QLG1 GPS. I somehow missed that it had this ability.
This was a huge help, and removing some turns and adjusting the inductance made the difference.
Thanks and 73!
AI6ZV
Very helpful video Hans. Thanks for taking the time to do this!!
Thank you Hans! Excellent, as always!
Thanks Hans! Mine went from 2.8W to 5.2W @ 13.8V by removing 2 turns and then fiddling with spacings. Mines a 20m QCX+ Rev4. 5W is good enough for me, I want to be QRP!
Removed 1 turn for L3 and hit 4.5 watts at 12v on my 30 m QCX +...Excellent thanks Hans
Outstanding video. Most useful. Transformed my power output using it. Many thanks.
I went back and tuned up all of my QRP-LAB purchases. 40M QCX went from 4.5 to 6W. 20M QCX+ went from 4 to 6W. I even tuned up the 50W 20M amp 35 to 40W @ 19.5V PS. Was so excited, I took my 20M QCX and converted it to the 17M with parts around the shop, tuned it up to 4.5W. Thanks Hans.
I only wish I new this trick when I was building the radios. :)
GREAT INFO! Thanks Hans. Carl
Amazing and excellent! Thank you for showing, in detail, how it is done! 73, de K08S
Excellent video Hans. I was able to adjust turns on my 30 meter QCX-mini and now have 5.0 watts output when using a 12.0 Vdc supply and yes I had to remove a couple of turns on L3 and also adjusted spacing on L2 and L1 (power measured on 50 ohm load using oscilloscope). Now time to start building my 40 and 20 meter QCX-mini's
Great video, Great transceiver.
Nice job showing the steps and explanation of the different parts / alignment / test points Hans =) Thank you very much for the great design of the kit =) Love it for SOTA / POTA / RaDAR outings =) Hope to get one of the newer kit later on after the parts supply is back up and the wait in line =) I do not mind the wait for a great product =) de N5VMO Pat ( QCX -20m kit pre-built ... bought used ... love to use it =)
Thanks, Hans, this has been a great help.
Excellent!! Thank you. I'm putting the 40 meter kit together now. This has been very helpful. I'll be trying the 80 meter and the 20 meter in the future.
73
Dave
WA7AXT
Thanks Hans,
a very very helpful video .
I like the performance of the qcx very much. I've already built two of this wonderful rigs (QCX+ 40m and 30m) and had no major isssues during the process. And sure I'm going to order one for 20m, too. Use them at home and in the field with best results.
73/72 Wolfgang, DL8ABH
My 1st look at at one of these units. Lots to learn for sure. Been away from HR for too many years. But I've got some renewed interest. Definitely will get one of these devices. Reminds me when I made my 1st TNC from kit. Loads of fun. Thanks! de KQ1K
Thanks so much for this very useful video Hans that I just ran across. I just finished my first QCX mini and with no adjustment yet I'm getting 3 watts out at 12v. I'll tackle a tune up after lunch, using this info. After that, in a couple days, I'll start into the 50w amp kit you I just rec'd from you. That FedEx was a nice quick service this time. I think I'm going to order a 40 and 30m kit and maybe one more amp. I still seem to be addicted to kit building, after all these years! hihiii
72, Brent VA3YG
The rate I work at, removing 2 turns and resoldering that inductor would have taken me a whole morning 🤣 nice video Hans 👍
OCD is a terrible thing. It seems to affect at lot of us tech types.
Hans... I recently asked you, at the LICW presentation you gave, how to get the output power up from 2.9W. You refered me to this video. Now running 4.3W @12Vdc. Thanks so much for this great video... Ron KA5HZV
That's awesome Ron! Glad to hear the video helped, it has helped a lot of other people too. 73 Hans G0UPL
Excellent video! Very helpful. I would love to see a fault finding video some day too. 73!
There's one already! czcams.com/video/zTmt_KF_xTU/video.html
Hans, removing 2 turns on L3 for 20m made my day, pwr went up from 2,5 W to 4,5 W on 12 V - 5,5 W on 13.8V - great :-)
Awesome, Thomas!
Excellent job Hans, just waiting for QSX mini and Father Christmas hopefully 🤔
The two QCX-mini prototypes (30m and 20m) are now assembled, debugged and operational. The first QSO was with the 20m prototype today Thursday 24-Sep-2020 with Feri HA2EOU who reported 559. The enclosure prototype should arrive here in the next few days. See my update with photos here: qrp-labs.com/qcxmini/qcxminidev2
Thank you I followed your instructions and was able to tune up my kit, and I can see an improvement over my initial build up.
Very helpful.
About trimers. I was way off with my settings not able to find any meter movement. I wondered about how far to turn the trimmer. I found that there seems to be a stop on one end of adjustment with a stiff feeling. "Didn't force it. Then at the other end of turns, I found the end of adjustments makes a slight clicking sound. I did get my QCx finally tuned but had to really go to other trimmers adjusting to find the sweet spot on all of them. Best of luck you will find the lows if you keep looking.
It makes me feel better that your workbench is a messy as mine
Hans, you need to use a lavalier microphone and get that audio up! Post production audio processing would really help, too!
Great work on the design of the QCX series though!
Michael - wb6csh
Some intersting mirror image scenes in there. It had me wondering if you were filming into a mirror, but I think not since the camera was not in shot.
The entire video was shot in single take, unprepared, unscripted segments, all using my phone. Some using the front camera, some using the selfish camera. The selfie camera mirrors. The scenes were put together using the "YouCut" app and trimmed where needed. I tried to remember to click the "Flip" button to re-mirror the selfie-camera scenes or should that be de-mirror or un-mirror. But one or two I forgot. I mean, just checking to make sure you're paying attention, Fred
Thanks for the video Hans...it's a huge help. Should I see a sign wave if I put my oscope probe on the "pwr" test point on the QRP dummy load? Thanks again
No... It has been rectified by the diode and capacitor. The Pwr test point should have a DC voltage, but there will inevitably still be some RF ripple on it. So if you have your 'scope in AC coupled mode then you will see a signal... but what you want to measure is actually the DC voltage.
73 Hans
Just built the 40m and it's great. Ordered the 20m just this morning. Would you recommend omitting a turn or two on L3 when I wind the toroid and just avoid the issue?
Do you fix those toroids with silicon or glue after adjustment? This is also portable equpment and "heavy" toroids are fixed with just copper wires and they may shake and move.
Very useful information, thanks! 72 de AI5DD
When will the QCX mini be available?
Tnx a lot Hans for the video, excactly the right time - just finished my 20m QCX+. Can you give a short info how you have connected and attentuated from the QRP-Labs dummy load to the scope.
The 'scope probe (10X) is connected directly to the 50-ohm dummy load. 50V p-p is well within the acceptable input range of the oscilloscope.
@@QRPLabs Tnx Hans, and your osci probe ist at 10X?
@@truhmi Yes 10X
@@QRPLabs What size resistor did you use to connect to spectrum analyzer?
@@johnasmussen7210 It's a 1K 1/4W resistor, in series with the spec ann which has 50-ohm I/P impedance.
I should do a better matched system but I did calculate it all at some point and test it carefully and everything was as expected and calculated.
Hi Hans, just removed 2t on l3, but mine qxc+ 20m is not able to go over 3.2w @12v. as suggested I spread the coil turns . nothing....
any more suggestion?
Hans, I'm headed your way with a six pack and we are going to clean up that desk and organize your cables (seriously, my desk looks just like yours).
Pat, bring the six pack. Or few. But the desk and the cables are a lost cause.
Thanks for that.! Mine arrives tomorrow 😀😀😀
I didn’t realise you could get them ready built- I may have bitten off more than I can chew.
Love the whole ethos though. Would have probably got the mini and/or the all band all mode one if they ready. But to exited to wait.
If I make a dog’s dinner of it, can I shamefully send it to you for “repair” for some money?
Keep it up Hans
73
Patrick
Hi Patrick, I can't accept them back for repair due to import difficulties on electronic items. But someone in UK would surely be able to help - the QRP Labs groups.io has a lot of helpful people many of whom are in UK. So don't worry :-)
QRP Labs haha. Thanks Hans. I was kinda half joking anyway. Really looking forward to the build. 😊
I'm wondering if you can mount the coils in a better way or with some kind of clue to give some mechanical stress relieve when carrying the item around eg?
People write various kinds of things about effects of various glues and varnishes on coil Q. Practically speaking I don't think it will affect anything if you put a blob of any kind of glue between the toroid and the board. As you say, it could be useful mechanically if you are out and about in rough places.
Hi Hans Do you apply the same rules of thumb for 17m band pass inductors?
Yes, same for any band (LOW pass though)... 73 Hans
Could you tell us when is the qcx mini will be on the market??
It's in production now. We are now waiting only for the LCD modules manufacture, and for the SMD components assembly. Then they will have to ship to me, and I will have to write the manual and build one for validation. It will probably be about 20th November I expect. There are 1,000 QCX-mini kits in the first batch.
Hello! Is it necessary go again to the whole retuning process, after playing with the toroids of the low pass filter?...
Thanks and happy new year! PY4HZT 73
It's best to do the alignment again because I do find that twiddling with the LPF toroids changes the optimum alignment a little bit. Not essential but optimal. Happy New Year
@@QRPLabs Thank you very much! 73
Nice job, tnx 4 the video !
73 N8AUM
Could the QCX's built-in ability to measure (relative) power output be used for the "power peaking" process?
ALSO, if I use my DMM to measure RMS voltage off my (QRP Labs) dummy load, it appears my power calculation is this:
P = (Vrms * 2 * sqrt(2))^2 / 50 ohms
P = 0.16 * Vrms^2
Does this look correct?
Yes the built-in RF power meter could be used for power-peaking. I think I mentioned this somewhere in the video if I remember correctly.
You can use the RMS function of your DMM if it is able to work properly at RF frequencies; bear in mind there may be some accuracy limitations. Your formula does not look correct to me.
Power output is Vrms^2 / 50
See qrp-labs.com/qcxp/rfpower.html for a full discussion on this.
I believe the calculation you were looking for is described below:
Take the Voltage reading from your DMM across the dummy load and add 0.6V to account for the voltage drop across the diode. This gives you your Peak Voltage (PV).
Voltage + 0.6V = PV
Take the PV and divide it by the square root of 2 (which is roughly 1.414) to give you the Root Mean Squared Voltage (Vrms).
PV / 1.414 = Vrms
Then you square the Vrms and divide by the 50 Ohms to give you the output power in Watts.
Vrms ^2 / 50 Ohms = X Watts of output power
It should be noted that Hans describes in build manual (and I'm paraphrasing here) this dummy load is not an "accurate" piece of test gear but a tool to get your QCX or other QRP rig aligned and tested. It will provide a close enough reading to let you know what your relative output power is like.
To clarify, I am talking about output measurement of the QCX transceiver in watts. The dummy load instructions seem to be quite different than how you are measuring output. I suspect both your method and the dummy load instruction method are correct but they are different ways of calculating the QCX output At least that is what I hope!
John please see my reply just now to your first comment.
@@QRPLabs Thank you so much for the clarification. I don't have an oscilloscope at the moment. Following your instructions I am getting quite close to 5 watts or thereabouts- I'm still fine tuning. l could also get a bit more power by increasing the supply voltage to as high as 16 v. II think I will be quite close to that with a 13.8 volt supply and will be satisfied with that. Also, I am getting the 50w amp kit. Thanks again , it is all quite enjoyable.
I noticed that you have much high voltage measurements than I get and that you divide the square by 400. The dummy load readings I get are much lower but QRP labs instructions for the dummy load say that we divide by 100. So are you measuring something differently than what am measuring or are the dummy load instructions incorrect.
I'm measuring peak-to-peak on the oscilloscope, and dividing the square by 400. If you measure peak voltage, then square and divide by 100 (peak is 1/2 peak-to-peak). The dummy load is measuring peak voltage.
You can read my complete guide here:
qrp-labs.com/qcx/rfpower.html
@@QRPLabs Thanks to your video on tuning up the qcx+, today I enjoyed my first qsos on my qcx plus with very satisfying 579 reports with hams 1,500 miles from home. Conditions were good but just the same it was great fun.
Hello Hans, any news of the QRP Mini ?
The two QCX-mini prototypes (30m and 20m) are now assembled, debugged and operational. The first QSO was with the 20m prototype today Thursday 24-Sep-2020 with Feri HA2EOU who reported 559. The enclosure prototype should arrive here in the next few days. See my update with photos here: qrp-labs.com/qcxmini/qcxminidev2
@@QRPLabs thanks, I love it. Be sure I'll order one as it's available.
I've tried watching and listening to the audio on three (3) different computers, and your audio is WAAAY down on all devices! Please do some audio processing so your comments are hearable!
For the process of removing turns, has anyone just soldered a jumper between two turns on the outside of the coil without removing the PCB connection? This should bypass two turns without disturbing the board.
I don't have specific info for the QCX situation. But in general having a shorted turn on a coil is very bad. It has lots of other effects besides just removing a turn. Think of it as a transformer, the rest of the turns still there work as a primary and they are trying to induce current into that shorted turn as a secondary!
So the question becomes: what if I am a ham with limited resources, say, without an o scope. Is this tuning still possible?
Yes! Please watch the video carefully again. Nothing in it requires an oscilloscope. I am merely using the oscilloscope to measure power output because this is the method I choose to use here. You can use ANY power meter you have. Or even achieve a lot with the internal power measurement - the accuracy is not great but it will give you a good measure of relative improvements and let you optimize power output. The other alignments are all done with the internal built-in alignment tools.
No oscilloscope or other equipment needed! QCX-series radios have it all built in.
Agree with Hans.
For base debug you need only 50Ohms and internal test sute. DVM for IC tracing and RF power meter LPF adjustment.
Having special tools allows do this more convenient and quick way.
Only I would do is updated doc with DVM voltage ofter PA with loaded to 50Ohms dammy load or LPF with input impedance 50Ohms.
The ONLY equipment for tuning power output like Hans is doing here is a Digital Multimeter (DMM) or a Vacuum Tube Voltmeter (VTVM). I'm assuming you are using a dummy load with a rectifier and coupling capacitor to measure power output.
The only problem I encounter when removing turns from ANY TOROID is getting than damned PC hole cleared of solder, so I can reattach the wire to the PCB!
Why do CZcamsrs feel the need to say “quick” video. Why? Many of us don’t prefer quick videos - the longer the better. Fortunately, your quick video here is 44 minutes long, and is a great length for many of us.
32:00 Did you just say turn it to 11? I thought it only went to 10? (thumbs up if you know the reference)...
Yeah turn it to 11. And I'm old enough to get the reference.. and it seems very relevant here!
P.S. see earlier comment on the mirror image video... Phone selfie cameras do this mirror image and during editing one needs to flip it. But evidently I forgot
Please check your email good sir
Dear Hans. I have the QCX+ and recently I have completed the QDX build. You have created great and fun stuff, PLUS the manuals are superb!
The 30m and 20m of my QDX are not giving significant power, but I know that I'll have to check the coils' enamel insulation. As to the fine tuning: would the procedure for the QCX+ (this vid) also apply to the QDX? I mean getting the low pass inductors right. VY 73 de HA7RJA