Re: QMX article in the QST
Hello Shirley, Steve
In my opinion the QMX should show considerably better strong signal performance than reported in the QST review. If you compare it with the QCX review for example, the QCX review in QST (on the QCX page) has better numbers. But this should not be the case, QMX has a higher performance receiver than QCX. I have made a lot of measurements of my own that demonstrate this. I suspect there might either be something wrong with the ARRL's specific setup and procedure for this review, or some issue with the unit they tested. Still - it is what it is and anyway the rest of the review is extremely positive, as Shirley said, keying characteristics, fast turnaround; and the very low receive latency.
73 Hans G0UPL
To put those numbers in perspective: the QMX doesn't have the strong signal performance of a state of the art 2024 design, nor should we expect it to at its price point. Aside from the number for blocking gain compression, which is likely caused by AGC action rather than blocking in the front end, those numbers would have been respectable for a high end rig in 1994. They're still good enough to make using the QMX on the air a pleasant experience in anything but the busiest contest conditions,?and better than we'll see from most rigs that?cost under $1,000. The excellent numbers for transmit keying sidebands are also worthy of note, and the fast T/R turnaround means that it will work well for full QSK. The CW keying waveforms are also outstanding; no shortening of the first dit, and both of the dits on the scope trace are the correct length.
On Sun, Oct 13, 2024 at 6:37?PM Steven Dick, K1RF via <sbdick= [email protected]> wrote: Thanks - colors did not reproduce correctly in the specs on the left side of P38. Here's a version with correct colors.
-Steve K1RF
------ Original Message ------
Date 10/13/2024 5:53:04 PM
Subject Re: [QRPLabs] QMX article in the QST
Here's a fair use copy of the review only:
?
|
Re: QMX article in the QST
To put those numbers in perspective: the QMX doesn't have the strong signal performance of a state of the art 2024 design, nor should we expect it to at its price point. Aside from the number for blocking gain compression, which is likely caused by AGC action rather than blocking in the front end, those numbers would have been respectable for a high end rig in 1994. They're still good enough to make using the QMX on the air a pleasant experience in anything but the busiest contest conditions,?and better than we'll see from most rigs that?cost under $1,000. The excellent numbers for transmit keying sidebands are also worthy of note, and the fast T/R turnaround means that it will work well for full QSK. The CW keying waveforms are also outstanding; no shortening of the first dit, and both of the dits on the scope trace are the correct length.
On Sun, Oct 13, 2024 at 6:37?PM Steven Dick, K1RF via <sbdick= [email protected]> wrote: Thanks - colors did not reproduce correctly in the specs on the left side of P38. Here's a version with correct colors.
-Steve K1RF
------ Original Message ------
Date 10/13/2024 5:53:04 PM
Subject Re: [QRPLabs] QMX article in the QST
Here's a fair use copy of the review only:
?
|
Re: Why not provide a MP3 of an actual MCX+?
Same here, it all personal preference and some amount of how I use it.
?
My favorite RX is still the QCX with the audio filter modded for SSB
(Hipass 250hz, LOpass2400hz).? And a lot of close seconds.
?
?
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
|
Re: QDX: Troubleshooting high output power
Please note that the bandpass filters are only for receive, so they shouldn't be affecting your transmit.? The low pass filters, along with the two binocular toroids are in the transmitter path - check them carefully.?
|
Re: Why not provide a MP3 of an actual MCX+?
Also before someone gets triggered I was having a bit of fun here. There are gross generalizations, biased opinions, and otherwise non objective feedback included in my last post. Mixed with a few facts about how Hans did indeed do great things to preserve quality in the RX path.?
please. Sleep well tonight, even if we disagree.?
i am also not implying that money in any amount makes one¡¯s training relevant ?. I don¡¯t work in audio at all now, nor do I have a stack of accolades next to my name in that arena. Again some fun.?
but I have heard some great audio in my lifetime, and some of it came from my qmx.?
|
Re: Why not provide a MP3 of an actual MCX+?
The QMX doesn't have a speaker, and how good the sound is will also depend highly on the speaker you use.? I agree with those that have praised the QMX audio, but have also heard it be raspy and annoying when I use the wrong earbuds, or when the volume is too high for the particular speaker attached.
|
Good to know.? Thanks!
?
?
On Sun, Oct 13, 2024 at 03:42 PM, Ronald Taylor wrote:
Hi All. Back in 2020 I mistakenly ordered a Si5351 that was pre-programmed for a fixed frequency and it did not work in a QCX I was repairing. I had to order the correct one that was not programmed. Since then I've only used the un-programmed versions, both Si and MS5351 depending on what was available.
?
|
Re: Why not provide a MP3 of an actual MCX+?
I¡¯m just a guy with another opinion. One that may be interesting to some.?
I went to school for audio engineering. I¡¯m a bit opinionated about what sounds good. I use an icom 7100 because it¡¯s a superheterodyne. I won¡¯t listen to a 7300 for five minutes. (My two cents you can sue me for). My qcx classic for 40m sounds amazing. Maybe I built a good one and my components all happened to gel. Maybe they all sound good I don¡¯t know. I was skeptical about the qmx. I built one. I¡¯m not anymore. It sounds amazing really impressed by what it does.?
real life example from previous life.?
i love the ssl 4000g into an mtr90. (7100)
?
?I¡¯ve used a 16bit digital all in one recording station. Or profools with low bit and sample rate. (7300)?
?
i was skeptical about digital after that but when i used a digital console with high end converters (dynamic range) high bit rate and everything running at high sample rate, the utility and the sound was great. Not the sames as analog but great, in many ways better (Qmx). Separation, dynamic range, etc. to much to talk about. Point is. Carol kings tapestry album sounds great. Green Day¡¯s American idiot album sounds great. There was some weird stuff in between.?
?
i think this same transition is happening in radio now. Exciting times. ?
?
the floating point and extra care Hans put into the RX. ?As well as the simplicity has resulted in a great circuit.?
bottom line. I am picky about how a receiver sounds. Even for cw note. I can listen to these kits all day, and not even be mad about it. ?Side tone too. (Try that with a kh1???) ?Buy three build them. Use them. If you don¡¯t like them give them to me. ?
?
?before the ele gang starts looking up my address to send me death threats, the k2 sounds good too alright? ?But to my ears trained with tens of thousands of dollars there isn¡¯t $5 difference between it and the qmx. Change my mind.?
|
Here are my output values by band. I did a little squeezing and expanding with the Low Pass Filters but didn't gain much. I'm not sure if these are typical or not.
?
BAND??? Output Watts
?
160???????? 4.8
?80????????? 4.2
?60????????? 3.4
?40????????? 3.6
?30? ? ? ? ? 4.1
?20? ? ? ? ? 3.1
?17? ? ? ? ? 3.2
?15????????? 3.8
?12? ? ? ? ? 3.5
?10? ? ? ? ? 2.5
?? 6? ? ? ? ? 2.3
--
73, Rick
VE7TK
Website:
|
Re: QDX: Troubleshooting high output power
Ok, I found that L4/L10 weren't soldered well.? Now I think I'm getting closer to right thing regarding the diodes, but still not sure they are quite right.
Running 9V, I am getting 7.2V across the diodes of the "off" bands and 0.67v across the diodes on the "on" bands.? However, the RF sweeps are still way off and it is still just transmitting for less than a second if that.
|
Hi All. Back in 2020 I mistakenly ordered a Si5351 that was pre-programmed for a fixed frequency and it did not work in a QCX I was repairing. I had to order the correct one that was not programmed. Since then I've only used the un-programmed versions, both Si and MS5351 depending on what was available.
Ron
Far as I know, the MS5351M has no documentation for its internal registers.
The only documentation for those registers is what was written by SiLabs for the Si5351.??
?
The MS5351M is not available from US distributors, you have to get them from China.
(EBay doesn't count.)
?
I defer to Hans on the question of whether a factory programmed variant of the Si5351?
is suitable for use in his products.?
?
Jerry, KE7eR
?
?
?
On Sun, Oct 13, 2024 at 01:23 PM, Bruce Akhurst wrote:
So as the original ones or the MS version are currently widely available and will likely be purchased and changed to trouble-shoot (not further confuse the issue) why would you even bother wondering
|
Re: QMX article in the QST
Thanks - colors did not reproduce correctly in the specs on the left side of P38. Here's a version with correct colors.
-Steve K1RF
------ Original Message ------
Date 10/13/2024 5:53:04 PM
Subject Re: [QRPLabs] QMX article in the QST
Here's a fair use copy of the review only:
?
|
Re: Why not provide a MP3 of an actual MCX+?
Hi Chuck,
I think I have the same feelings as you when it comes to CW. ?I had two Yaesus, with cw filters- different machines, and I just could not have a pleasant experience with either of them on CW.
?
I went to a couple of older Elecrafts and had an ¡°aha¡± moment. ?Easy to listen to the code, and I was not fatigued after a few minutes.
?
I have a QMX+ running v.27 as well now.
?
All I can say is Wow! ?How did Hans do this? ?I A-B¡¯d the K2 with the Qmx+. ? The QMX+ is punching way above its weight on receive!
?
73,
de Chris W3PB
|
Matthew,
My 12 volt QMX draws plus or minus 200 mA at first, then drops to 95 mA once the switching power supplies are working.
Is your current limit set high enough to allow the initial inrush current? I had my power supply set too low at first, around 140 mA,
and the voltage would drop dramatically as the current compliance kicked in. I thought there was a big short at first.
Since the radio wasn't actually running there was no USB connection, either.
?
For transmit I need to have the supply current set to 1.1 A or a bit higher.
?
Best of luck,
David N6AN
|
Re: QMX article in the QST
Here's a fair use copy of the review only:
?
|
Re: Why not provide a MP3 of an actual MCX+?
Interesting that you call IC7300 as "WARM" when many like to?
complain about the hiss.? I have one and it has with the
gain up a lot of HISS compared to my TT Triton.
?
Myself I find the Q(C/D/M)X kits audio very good to my ears
when below overload levels.? When at overload levels they
are like many to my beat old ears.. distorted.? Not their fault
just my lack of applying the volume control.
?
--
Allison
------------------
Post online only,?
direct email will go to a bit bucket.
|
Far as I know, the MS5351M has no documentation for its internal registers.
The only documentation for those registers is what was written by SiLabs for the Si5351.??
?
The MS5351M is not available from US distributors, you have to get them from China.
(EBay doesn't count.)
?
I defer to Hans on the question of whether a factory programmed variant of the Si5351?
is suitable for use in his products.?
?
Jerry, KE7eR
?
?
?
On Sun, Oct 13, 2024 at 01:23 PM, Bruce Akhurst wrote:
So as the original ones or the MS version are currently widely available and will likely be purchased and changed to trouble-shoot (not further confuse the issue) why would you even bother wondering
|
Why not provide a MP3 of an actual MCX+?
What a great persuasive writeup on the QRP Labs site for the QMX+.?
?
Since Audacity graphical output is used in the presentation,
why not attach the actual MP3 file?
?
With my present degraded hearing I find CW audio output from
the QCX et al kits unpleasant and very hissy. Not warm at all
compared to (say) a 7300 or 710. I am reluctant to buy further kits.
?
Would it be possible to prepare a preview listening experience?
?
Chuck w8mqw
|
Something is pulling down on the 3.3V supply so the power-up sequence cannot complete.? That is why IC101 is getting hot - its output is shorted (or nearly shorted) to ground by something.? Or maybe it was defective in the first place, but that's not very likely.
Note that the general power-on process is this:
1 - pressing the power-on button turns on Q103/Q105, which puts the voltage from the input jack on the +12V rail
2 - this +12V goes to the input of IC101 which creates the initial 3.3V VDD voltage via D103, which is also connected at the top of D109.
3 - this VDD voltage powers on the CPU, which then sets up the switching power supplies, and turns on VCC via Q108 and switched VDD via Q111.? The CPU then turns OFF the IC101 3.3V (i.e. changing from the linear 3.3V supply to the switched one).? This all happens in about 1/4 second if all is working well.
So when you press the button and only 12V comes on, usually it means the initial linear 3.3V supply (IC101) isn't getting voltage to VDD to power up the processor.?
This can happen for multiple reasons.? If you can measure 3.3V at the output of IC101, but not at VDD, it often means that D109 (the protection zener diode) is blown and shorting the VDD pin to ground.? It could also be soldering issues, connector issues, or other components further downstream.
So the first trouble-shooting step is to check D109, and everything on the 3.3V power supply board.
And if you haven't already done so, look at the Wiki on this group, it has lots of pertinent info:
And this video is worth a review, it has lots of common issues to look out for:
Good luck.
?
|
Jerry
As the kits have never been designed/tested? for anything but the standard Si /MS 5351's they were sold with - and the earlier models were pretty tight for code space to cover other options)
- And I have never (even during the great 5351 shortage) seen it said that any 5351 version with any factory programming will work in any radio.? ? (Maybe I missed it but? . . . . )
So as the original ones or the MS version are currently widely available and will likely be purchased and changed to trouble-shoot (not further confuse the issue) why would you even bother wondering
But if someone with a working radio has time and wants to try it on all modes/bands/conditions and report back maybe its fine.? I just don't see any reason to add another variable to a tricky repair if its avoidable.??
|
Shirley Dulcey KE1L
Rick Williams - VE7TK
Ronald Taylor
Chris Raine W3PB
Randy K7RAN
Bruce Akhurst