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Your QMX output experiences @12volts...?..and by the way, what an amazing radio.
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Jerry Gaffke via groups.io <jgaffke@...> wrote:
If your eyes glaze over when you read that, you probably wouldn't useThey don't, I just want a clean reception. For the price, there is nothing comparable to a QMX.This is true... and it was the winner when I searched for my first CW radio (probably still is). Well, I had good experience with QDX before. If you do spend the money on a better radio, the QMX would still beSo... I did. FT-891 is on its way. Mostly because it was my dream for a long time to have a proper, factory-made radio, I just never wanted to spend the money. QMX will stay with me, probably for portable operation (we'll see... 100 W sounds impressive compared to 5 W, but I don't see myself carrying a car battery on my back, so for field trips I'll probably still carry the QMX). I'm reading the manual for FT-891, many features (like the mentioned IF shift) don't make sense to me yet. I'll probably figure them out and see if I really need / use them... One drawback is that FT-891 doesn't expose the virtual sound card the way QMX does. All this money and I'll still have to make a digi interface and connect two things to the PC (USB for CAT and external sound card), play with audio levels, etc. Disappointing. But I guess it's the standard, and QMX is an exception. |
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Adam,
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You should read again some of the responses in this thread.
The consensus seems to be that the QMX receiver is quite good, but without some bells and whistles.
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As Stan Dye says, the more expensive receivers might have:
"noise blankers, IF shift, built-in attenuator and pre-amp, automatic/manual notch filter, adjustable digital noise reduction, etc.? And the K3 has a fully independent sub-receiver for split operation or synchronous diversity receive from two antennas."
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If your eyes glaze over when you read that, you probably wouldn't use them much.
The noise blanker and notch filter might be useful if there are other signals sitting on top of what you are trying to receive, and might be "just" a firmware upgrade if Hans has the time for it in the next 10 years or so.? Not something I normally need, especially if I have a sharp and narrow filter.
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If curious, I suggest you stop by a store with demo units out, ask the salesman to demonstrate each of the above features.
Read the manual thoroughly, see if those features are easy enough to use that you would ever bother with them.
If interested in portable operation, compare size and weight.
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Ask about the price too.?
For the price, there is nothing comparable to a QMX.
If you do spend the money on a better radio, the QMX would still be there for portable use or as a backup.
For many of us, building and improving the QMX *is* the hobby, not an option if we had an FT-891.
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Jerry, KE7ER
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On Tue, Jan 14, 2025 at 07:07 PM, Adam wrote:
But what if we only compare their receivers? Like apples to apples. |
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Daniel Conklin via groups.io <danconklin2@...> wrote:
The FT-891 is in a different class and is designed for differentBut what if we only compare their receivers? Like apples to apples. There's a signal and an antenna -- same signal and same antenna. Is it possible for QMX to completely miss the signal, but for Yaesu to receive it well enough to be readable? Does it happen? I guess all this complication (I just looked up diagrams of FT-891's, focusing on the RX path, and it's bloody complex) serves a purpose... or does it? |
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Thanks Don,
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This is new information to me. I did not look beyond the red and black pairs. I did think about color coded wires. I am using 14 gage red and black wire. Those other combinations would help.
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In this list of messages is a fresh new assertion that the QMX will absolutely puke with more than 12.0 volts applied. Maybe some day I will change my mind but for today I will avoid any "12 volt" radio that puny.
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Onward with the QCX and other tough radios.
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73,
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Bill ?KU8H
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On Mon, Jan 13, 2025 at 09:00 PM, Bill Cromwell wrote:
I use both color-coding and housing orientation to avoid this; my 12V is ARES standard, other voltages have different housing colors and orientations, they will not physically plug together if mixed.
73, Don N2VGU
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My QMX-Plus has steeper selectivity skirts (programmable) than my FT-891.? With both set to a 50 hz bandwidth setting listening to CW at the lower ends of 20 and 40 meters, my QMX+ seems "quieter" when referencing the no-signal background noise level.? Somewhat relative of a comparison, I can copy the weak signal on either rig.
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Mark K9TR |
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The ATU talk makes me cringe as well, but because it can do the opposite of protecting your radio.? When it's looking for the lowest possible match, it will explore some regions of potentially high SWR.? That can blow your finals unless you somehow reduce power.? And I rather like twiddling knobs, guess it makes me feel like I'm in control and gives me an opportunity to learn about my antenna.? When I want convenience I reach for a cellphone.
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I'd argue that an end fed half wave is ideal for portable use.? Radiates as good as a dipole but resonant on twice as many frequencies, gets fed from one end which might be conveniently near your tent or picnic table.? No fancy tuner needed just a suitable matchbox, some EFHW designs can hit? 80, 40, 20, and 10m without adjusting anything.? That said, experimenting with better antennas is to be encouraged.? The radiation pattern from an EFHW is pretty much pot luck on all but the fundamental.
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Jerry, KE7ER
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On Mon, Jan 13, 2025 at 06:02 PM, Scott VY1CO wrote:
All of this talk now about cramming an antenna tuner into a qrp rig makes me cringe...it does nothing for you but protect your radio unless you step out of the box and begin to understand how running non-resonant antennas--be they loops or, ideal for QRP, balanced line? fed doublets. I fear we have started to raise a generation of end fed antenna users, but I will save that for another diatribe. |
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Some really interesting perspectives here.?
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I grew up in ham radio during high school and mandatory code--I consider myself lucky. 80 percent of my qso's are cw. licensed since 82...none of that matters, but it brings perspective.?
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The 'problem' with qrp is that many carry over the minimalist approach to every aspect of the hobby--especially antennas. Yes, there was a guy who once worked a ZS6 station using no more than1 watt and? a G5RV positioned 5 feet off the ground, but it only happened once. Propagation is the greatest determinant to our success, and often it works against us and our schedules.? 4 or 5 watts cw is actually a lot of power when properly transferred to antenna...but you need a decent antenna. If you want to work anything worthwhile on QRP, you need a good antenna. Its worth repeating.? Period.? All of this talk now about cramming an antenna tuner into a qrp rig makes me cringe...it does nothing for you but protect your radio unless you step out of the box and begin to understand how running non-resonant antennas--be they loops or, ideal for QRP, balanced line? fed doublets. I fear we have started to raise a generation of end fed antenna users, but I will save that for another diatribe.
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As for the power discussion, which seems timely given my recent dealings with the 50 w Amp, it makes a big difference...frankly, 25 watts CW with a good antenna is optimum. Again, only if you are able to transfer the power out. The QMX is a brilliant little radio, as is the QCX...I have them all and I can tell you that I get as much or more enjoyment from making a contact on those as I do running the Orion 2 or the Elecraft...likely more, to be honest.
But that is comparing Apples and rocks...I don't play with the amazing QRP Labs gear because its the best/easiest? way to make an actual contact, I do it because I learn a lot from the experience. I learn a lot from this group and the help I get on the mistakes I make, and seeing how others overcome theirs. That is the essence of Amateur radio. Without that, we are little more than appliance operators.?
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I often try to explain to people that QRP is very much like fishing--fly fishing. You know, how gentlemen angle for fish. We could use a net or, worse, a hook and a worm, but for those of us who appreciate the art, we tie our own fly's, we plan and stalk our prey,? and do so in the least disruptive manner.?
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So to bring this back to where it began--somewhat--I do just fine with 2.5 watts and a yagi at 72 feet...but if I am out on the trail with just my doublet and some 450 ohm ladder line, I want to get every damn watt I can out of that rig. Nothing worse than being half an S unit under the station you want to work.
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Now back to this pesky 50w amp that sonly giving me 10 watts out @13v with 4w input :)?
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73
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Scott |
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Thank you for your response. You suggested something like a "tune" mode that reduces power to 25 percent. Can the radio be operated in that mode? Is the power reduction continuously variable? I will take time to study the manuals somewhat to see how that looks in operation. It would be ideal if I could that.
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About fiddling with the supply voltages..I really want to avoid that. I have poor luck and lots of effort to get some digital gear that I can use with my radios that does not scream in the radio's ears. All of it runs on 5 volts or my "12 volt" (12 to almost 14 volts). That includes a Raspberry Pi and a couple of accessories on 5 volts and a small screen about the size of my iPad on the same 12volt batteries the radios use.
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I won't re-use the Anderson Power Poles for any other battery system to avoid the inevitable mixup. But I could use something like polarized plugs sold for automotive use on lithium battery packs with 3 series cells for something around 10 to 11 volts. No digital hash and no power wasted in a dropping resistor or diodes. Just more stuff to drag around on portable ops.
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This with other replies has me reconsidering a QMX+. I will look through the manual as before I ask any more questions about it.
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73,
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Bill ?KU8H |
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I have an FT991/A and an Elecraft K3s -- and my QMXs, QMX+.
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The receive on the QMX is clean and clear, with more-than-adequate sensitivity (at least in my signal environment).? So it in some ways competitive with both of the commercial rigs.
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But the receiver on both of the commercial rigs is also much better by some measures: noise blankers, IF shift, built-in attenuator and pre-amp, automatic/manual notch filter, adjustable digital noise reduction, etc.? And the K3 has a fully independent sub-receiver for split operation or synchronous diversity receive from two antennas.
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And as good and clear as the QMX audio is, the K3 has a better audio amplifier with several adjustable features including multiband equalizer and digital audio effects.
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And they have a built-in 100W multiband linear amp, so I don't need to try and cobble together something with switchable lowpass filters.
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So as others have said, they are really not in the same class, and can only be compared on a very small subset of features.
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But if the 'fancy' features are not important to you, the QMX is way more than adequate, it is excellent.? And I love mine, not only for portable operation, but because it is fun to operate something SO TINY that is such an amazing multiband, multimode radio.
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Stan KC7XE |
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Adam,
I had a Yaesu FT-891, and the receiver is hot, maybe too hot! Also it has a strong audio output amplifier designed to mobile use. I sold the FT-891, even though I loved it, and bought a QMX, then a QMX+. I have not been disappointed, but the QMXs definitely have different quirks from the FT-891, and even from each other. The FT-891 is in a different class and is designed for different purposes from the QMXs, so it's difficult to compare them fairly.
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73, Dan - W2DLC |
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Stan Dye via groups.io <standye@...> wrote:
I do not believe QMX finals are nearly as fragile as they are reputed toI blown finals in my QDX by driving a poorly matched load (including when the BNC connector made a poor contact). QMX has a protection against large SWR. And yes, if QMX had an output drive/power control, you could eliminateThere's hardware for that, so it should be easy to do in firmware... On the other hand, you can just lower the supply voltage. |
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Stan Dye via groups.io <standye@...> wrote:
I'm not going to bother with that.? The QMX is supposed to be QRP, andThe problem, as always, is money vs time. For a long time I didn't want to spend money on a proper, factory-made, 100 W transceiver, especially as I'm mostly interested in CW, so a transceiver doing SSB would be an overkill. I'm still weighing pros and cons (DIY vs something that just works, plug and play, and is on warranty in case it doesn't). On the other hand, QMX isn't too complicated for me to diagnose and fix. It's a simple and elegant circuit. A factory-made rig, once warranty runs out, probably would be. My concern is with the receiver. How does the QMX receiver compare to the one in, say, Yaesu FT-891 (a rig I want to buy)? |
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That’s what the “tune” menu does. With a selectable percentage. ? When I use a match with my qmx it’s a BLT + that I built which has a dummy load in line with the antenna, so that cuts the mismatch down to 2:1 max. Then, I go into the tune menu at the frequency I’d like to operate and it puts out 25% power into the tuner/antenna. I fiddle for the dip and we’re off! ?I’ve not had any final issues with any of my qrplabs kits. But I believe the function you’re looking for already exists unless I don’t understand the ask, which my wife will tell you is a possibility ?.? |
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A relatively easy way to deal with the QMX power in your situation is to get one of the inexpensive buck-boost power modules (the 3amp ones are very small), set its output for 12V (or your desired setting), and build it into your powerpole to QMX cable adapter.? ?These work quite well for qrp voltage regulation, and work with your supply voltages.
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Thank you for your input Stan,
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I looked at the info in QRPLabs web site and I see that the QMX series have the same final transistors as my QCXs and the PFR-3. My experience is those are robust parts. In have not looked to who is running classic, D, or E. That might make a difference but it clearly states those transistors in the QMX do not even need a hearsink.
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It is possible to destroy some pretty rugged vacuum tubes leaning on them too hard. some of the same cautions apply. Meanwhile My ham hobby has been morphing into the 21st century. My sealed lead-acid 12 volt batteries get up a bit over 13 volts at full charge and the new LiFePO4 batteries get closer to 14 volts with the present charger. I have all of my "12 volt" stuff using the Anderson Power Poles and all the 5 volt stuff using USB cables & connectors. I have two different kinds of power sources and I would like to not clutter the local environment or picnic table with several more. It would be trivial to acquire an 11 volt supply, a 9 volt supply, and on and on then inventory several different connector types to avoid disasters. Too much stuff to carry to the park or to Field Day. Also clutters the desktop.
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So now I have mentioned some of my reasons for asking my questions. If I get more responses like the two I have now I will move the QMX up on my list. I do not require every last milliwatt so all I need is the means to reduce power for rtty and other high duty cycle modes. Meanwhile..I can operate one of those on CW as it comes off the bench. I started with two watts on CW and SSB and worked a lot of QSOS with modest antennas.All those bands in one small box!
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73,
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Bill ?KU8H |
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I understand qmx is more complex than the qcx, and ability to do ft8 wspr etc can stress the transmitter and possibly also the dc/DC. I would be interested in operating wspr on 160 and 80 meters, where a few watts may be more beneficial. Here I sense need to drop supply a little below 12 volts, and I see a boat anchor bench supply across the room that can do that.?
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I did fire up the U3S on wspr, it's stock output is adequate still on the upper bands. Only one final is at risk here.?
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As for QRO when the QMX can do SSB, even a 20 watt PA might be an asset.?
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Let's patiently see what emerges.?
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Curt
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Donald S Brant Jr
Mark K9TR
Daniel Conklin
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