Re: QMX+ Output Power Adjustment
Unfortunately there is not yet a firmware control to adjust the output power during operations.
The hardware capability is present, so we can hope for a future firmware update that will allow us to change the % of full output power we want to use.? (Currently that is only available for 'tune' mode).
Stan
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Re: QMX+ Output Power Adjustment
Larry,
The output power is affected by the input voltage, within limits. If you have a QMX+ that's built for 12 volts, then the highest voltage you should power it with is 12 volts. The transmitted output power is going to vary a little from band to band and from build to build. I get about 4.5 watts out on 30 meters, but about 3 watts on 10 meters. I can use a buck converter reduce my input voltage to as low as 7 volts. Maybe you could go a little lower than that, but it seems to operate reliably at that level. That significantly lowers my output power, but I can't remember now what I get on each band with that.
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73, Dan - W2DLC
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QMX+ Output Power Adjustment
I'm on the verge of buying a QMX+; the technology is just too good to pass up!? I had misgivings about the QMX because it didn't cover every band and also because of its small size. ?My camping and backpacking days are long over, and everything I do now is from the comfort of my home shack.
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My main mode of operation now is FT8/FT4, and I'm using my FT-817 for that. ?My intent is to try the QMX+ in that role. ?
On the '817 you can select different RF output levels by cycling through the available levels using a function button. ?I generally start a contact using 2.5 watts and then bump it up to 5 watts if there's difficulty in completing the contact. ?Just pressing the button once changes the power to 5 watts. ?
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I don't see anything like that on the QMX+. ?
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So here's my question: How do you change the output power on the QMX+? ?Is there a menu function to select the power? ?Or can the output power only be adjusted by changing the supply voltage? ?What's everyone else doing; do you just leave it at the same power level, or are you using some means to adjust the output power as needed for each use??
Larry, WA2VKG
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Martin, first check the 5v output of the voltage regulator (IC11). Next, look at the cathode end of D3 near the front left side of the board. You should see your 12v input there (less the diode drop). Also make sure the D3 cathode is toward the front of the board. If all of that is well, then it is likely that you have a bad solder joint or two associated?with?the 90 degree pin headers and/or the sockets on the front panel board. Or an issue with the on/off switch. Try those spots and let us know what you find ... 73 .. .Ron
Just finished the build. Nothing at the LCD. No voltage at pin 3 or at any lead of R47.? Would appreciate some guiidance as to how to troubleshoot.
Thanks
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I'm just reviving this thread to see if others have had any further success with the 50w Amp. I went around the horn a couple times until I remembered reading something about this. I had issues with erratic, low tx out of the amp when connected to the QMX. Aftew going through one end of the amp to the other--including replacing the 4.7k POT with a multi turn variety, same results.?
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On the qcx mini, it works flawlessly as designed at about 23 watts, 13 volt supply.?
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I have re-read some of the comments here but don't quite understand the issue causing this problem; the ptt is putting the amp into transmit, 4 watts input to the amp and dummy load and Bird 25w slug...power jumps around from 10-15 watts out, but very erratic. Just curious whats going on (SWR safety is disabled)...its as though the qmx is throttling back on the input power?
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If nothing else I have re-confirmed the amp works A-OK with the qcx as designed...
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Scott vy1co
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Re: QMX and QDX - Not enough 5V PTT oomph
Sounds like a great plan, let us know how it turns out.
Be sure to measure your PD outputs if you try to use multiple voltages from the same power bank.? My power banks wont switch one port to 9V/12V with a trigger cable, and simultaneously output 5V on the other port: as soon as I plug something into the USB-A port, the 12V triggered output switches down to 5V also.? I understand some power banks do support independent voltage output, but you need to find it in the specs.? Or just use your second power bank like I do.
Stan
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Hi,
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IMHO design and instructions for all QRP-Labs is exceptional and this is also often reason for many troubles and issues you see on the forum.
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I personally build 2 QMX and both times all was working straight off the bat. It is true that some tweaking with LPF/BPF is needed to get good results but this would happen with any kit available on the market. QMX is no different to uSDX, (tr)uSDX or mcHF in that respect.
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In the earlier days there were issues with blown finals but this is user errors (99%) now days software has protection build in so all you need to do read manual and switch it on. Still many builders fail to do that.
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QMX by design is portable rig, but to me it is a bit fragile electrically for that. What I mean that all needs to be connected in the right way and switched on at right sequence other wire you can blow your power supply or other parts. This is the only gripe I have. I still love these radios and repaired mine twice already but I want to use it and not have it in bits on my workbench.?
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When I say fragile I mean pulling power plug before switch off should not be a problem, connecting equipment (PA) in wrong moment also. So as long you do not ruch (as I do) and follow procedures you will be fine.
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73 de Marek SP9TKW
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Re: Best QMX AGC settings?
I noticed the crackling noises when I was operating this weekend, using my new AGC settings.? They seemed to happen when the AGC was not engaged.? In other words, I heard crackling when the signal was weak, and the audio was better when the signal was strong.? For the record - I really like my new settings, especially when I hit a birdie!
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| Threshold |
4 |
| Slope |
80 |
| Noise |
10 |
| Hang |
30 |
| Smooth |
50 |
| Recovery |
10 |
| Sample |
2 |
| S9 |
S6 |
| AGC display |
ON |
| AGC dB per bar |
3 |
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73,
Mike, KL7MJ
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Mike,
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I too had the same trepidation about buying the QMX+ kit because of the number of folks posting their issues. ?After looking at the posts, I realized that a great many were user caused issues related to soldering, wrong part placement. Etc. ?without knowing the total number of kits built, the number of non- builder issues is just a vocal minority. ?
although I did not post my issues with the kit build, I suspect that I am part of the majority that just didn’t solder as well as I should have. ?The built in diagnostics and post from the great and knowledgeable folks like Stan and Ludwig saved me from the embarrassment of needing to post for these common problems.
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my advice is that if you are inclined, go ahead and get a QMX+. ?There are plenty of folks to help you get a working device if it doesn’t fire up immediately?
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Len KJ9E
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On 14/01/2025 14:09, Mike via groups.io wrote: Is this just a small 'vocal' minority of builders having issues Mike, Without a proper survey how can anyone tell? On the whole do successful builders use the group much less? Thousands get sold, I'd expect most failures, for any reason, to be reported. Most failures seem to get sorted providing the owner persists. There is a core of members that diagnose, some offer physical help. What more can you ask for an advanced project? There are no doubt simpler, easier to build kits if that's what you want. 73 Alan G4ZFQ
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Re: Your QMX output experiences @12volts...?..and by the way, what an amazing radio.
Don,
?I am curious as to your housing colors and orientation for your different voltages. Could you describe them or produce a picture?
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73, Dan? NM3A
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Just finished the build. Nothing at the LCD. No voltage at pin 3 or at any lead of R47.? Would appreciate some guiidance as to how to troubleshoot.
Thanks
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Re: Blocking a band on QMX/QMX+
Larry,
????
An old post to this forum (that I can't find now)?recommended that in
the PuTTY Band Configuration screen, you change the band's "Band Name" to 0
(zero).? I've done this and it works.? It eliminates the band when
you switch the band switch from the front panel.
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Bill
W2EB
East
Syracuse, NY
On 1/13/2025 at 4:13 PM,
Larry Christensen via groups.io < larryna0f@...>
wrote:
toggle quoted message
Show quoted text
I would like to block out the bands I don’t use.?
I asked this once before but never got an answer on how to do it if it is
possible.?
That would make moving though the bands I do use much
easier and faster.?
TIA
Larry NA0F
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Re: QMX and QDX - Not enough 5V PTT oomph
Thank you again Stan.
Ordered some 2N7000's and other bits and bobs. Got everything bread boarded and verified and am now waiting on an order of 1/4 size proto boards from AdaFruit. Will build out some dedicated, relay switched PTT attenuators of various values.?
Decided on powering the relay side with a simple USB-A cable for the 5V relay source.? ?I have had good results using PD power banks on my Q's and have leftover output ports and plenty of capacity for low amperage add on's like my mini cooling fans.?
Gosh ... This QRP'ing is great fun!? So very glad I caught the QRP-Labs bug.?
On Tue, Jan 7, 2025 at 7:17 PM, Stan Dye via groups.io <standye@...> wrote: Greg, a better solution would be to add a FET switch to turn on your relay - the gate of a FET is what the output of QMX was designed for, not to directly drive a relay.
A simple FET switch and a 470nF capacitor across the relay terminals, with a 9V transistor battery (or 5V arduino power source) would work well to switch your relay.
Stan KC7XE
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Re: Blocking a band on QMX/QMX+
Hans?
Thank you for your answer.?
I will wait for the time that change is in a firmware update.?
I know you have more important items to keep you busy.?
Larry NA0F?
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I also built mine with the 250 Ohm resistor for the LCD brightness and wired a 25Ohm pot to the case so I could control the brightness to my likeing rather than hard wire the 3 or 4 options.
But great looking enclosure!
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Bob
KG5GTE
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I've been following QRP Labs since before its inception and praise the quality
of design, build and support for the kits, as well as the innovative
inspiration that brought them to market.
However, I'm looking at buying a QMX+ but I'm seeing lots of folk with issues
with the PSU modules and LPF's.
Is this just a small 'vocal' minority of builders having issues or has Hans
innovated a shade too far with the PSU's and pushed the limits of LPF
tolerances, introducing a measure of unreliability?
I think I have bought just about every kit that QRPLabs have released, in many
cases multiple examples, and really appreciate the value for money and the
support that the kits bring but I must admit my nervousness about aquiring a
QMX+.
comments? brickbats etc welcome. 73 Mike
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What should be the ideal values?
73! de Bekir TA2RX
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I thought about that too. Thanks for the suggestion!
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73, Dan - W2DLC
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Daniel Conklin
Ronald Taylor
Marek SP9TKW
Mike