QMX build for [40m/30m] , [20m/17m] & [15m/12m/10m]
#qmx
I just joined the group after ordering a QMX kit. If possible I’d like to build it from the outset for the band groups stated above. I accept that this will require total redesign of the filters. For simulation I intend to use QUCS which is now available via Ubuntu Software. And I have a NanoVNA to help with the practical work.
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But before thinking too hard about filter design I’d like to know more about the likely performance of the remaining hardware at higher frequencies. Particularly the Tx output power and Rx noise figure (especially as there is no LNA). To look in to this these things I was thinking that I might first link out the filters with a direct coax connection???and thus measure the raw Tx power and Rx NF available at the BNC before filter losses. And then I wondered if anyone else had already done that?
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Another issue is that my intended radio would be for seven bands. Does anyone know if the firmware can accommodate seven bands, and whether or not the user can determine what the bands will be without having to get modified firmware?
- Nick, G4IKZ
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Re: ultimate S3 .. how to solder on an antenna
?Hi Kristoff, et al,
re... coax antenna connection
Take? lQQk at this
https://qrp-labs.com/ultimate3/u3mods.html#ant
COAX but no connector to fiddle with
72
John
N3AAZ
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Hi Dennis
Ok yes, I suppose D101 doesn't necessarily blow every time. The 1N4148 absolute maximums specify 2A for 1us, 150mA avg current, 0.5W dissipation... If the abuse was short enough and/or you were using a current limited supply and/or with a bit of luck... It could stay alive. 73 Hans G0UPL
On Sun, Aug 13, 2023, 12:44 AM Dennis Rieger < kk5db@...> wrote: Hans,
Unless I am missing something the diode D101 has not failed even though I had a short between the two drains. I powered it up after I moved Q103 and it has been working just fine.
Dennis
KK5DB
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Re: FT8CN English manual translation
I have also used deepL to translate legal documents from French into English. A little post-editing is sometimes needed but the results are more intelligible than the original.
John F5VLF
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On 10 Aug 2023, at 07:48, Timothy Fidler < engstr@...> wrote:
Don't use Google translate; Use? ?DEEPL? from Germany as available online . Deutscher Qualitat versus? US high tech half As$ equivalent. US is very good at slick stuff that in fact is pretty flaky . After Apollo,? things in the US kind of went to hell in a Hbasket except in very specific areas where if you? messed up you went to Gaol for a hundred years and lost ya shirt too..... Back to Deep L?
Deep L puts in synonyms where? there is? a repetition? of a given word - that's pretty slick. It also handles bulleted lists natively . It handles about? 2.5 x as much text per Tx? in the on line version.
Nope my brother does not own the company.?
Bleat from me -? If anyone works out how to download and get running on a? Win 7 OS I am all ears for an idiot guide.??
I used DeepL? to do the translation E to? French of the? Qcx Mini manual . For nix? , Cause I love? Hans so much.? ? It was interesting exercise.? It's amazing how much work is required to do it as a clean job. You have to do the rough cut with DeepL and then do a clean up by hand .? For instance what do you do when there is Embedded? Anglit text in a??Photograph ??? ?- in my case ... not a lot - but I added more description underneath.?
That's a hint for anyone writing a tech manual that may need translation.? Embedded text might look sexy but it's not conducive to a clean translation.?
French specific notes -?
French tends to be more terse than English so you have fun trying to keep the pagination the same.? I decided to leave all the Front TOC in English so that upgrades on future versions of the manual would be easier to track.? Working smarter not harder.. something like that.? I'll stop before I put my foot in it. Vive La France.? Vive Madelaine.? ?
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FDIM 2023 Hans Summers G0UPL "Evolution in Radio Design: building the next"
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Hello Everybody
I recently finished the assembly of a vanilla 40M QCX-mini kit... ** I put power to it (9v from wall wart) and.... Boom, works as expected. Yay, me! I took a leisurely?week, a couple hours at a time, to put it all together.? Amazingly well-curated instructions!??
Thoughts?/ observations:
I couldn't budge the peak of the BPF until I removed the anti-static bag I had placed underneath the radio's PCB.? Doh!??
I have the QRP labs dummy load and with the 9.33V wall wart supply, I measure 12.03V at the RF detector.? Using the handy graph ("Guide to RF Power Measurement" ), and adding a nominal voltage drop from the diode, I guesstimate 2.5W out.? Any thoughts on relative increase in voltage/Watts out, if supply is bumped to 14V???
Additionally, I carefully?wound?the inductors as evenly as possible, and spread the windings out to fill the entire toroid, with no large gaps. I watched the video about?tuning the CQX and my initial power measurement (with stated caveats) seems pretty encouraging.? I'm curious as to potential gains if I monkey with the windings on the inductors.? The aforementioned video was pretty specific to a 20M build.??
I really like the idea of the built-in power meter (understanding its limitations), but I find the instructions in the "Guide to RF Power..." a bit confusing.? It mentions a 3-pin header, but it seems to be a 4-pin header on the board and schematic.? I'm a little nervous about roaching my radio with a ham-fisted mistake.? I want make sure I know what I'm doing, and the fantastic quality of the instructions makes me doubt myself.? I think I need to connect a jumper from the RF pin to the center conductor at the BNC connection. It makes sense to me that this jumper would naturally go under the main PCB.?
**? I have since ordered the AGC and TCXO modules after appreciating their value and functions.? Easy upgrades to make!
I have dreamed of building a QRP CW rig for years, and huge thanks to Hans for all his excellent work and support.??
73 Todd KE7AJZ --
?? ? ? ? ? _ ? ? _ ? ? ? ? ? ? ? ?
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/ __|/ __| '_ \| |/ _ \ '_ ` _ \?
\__ \ (__| | | | | ?__/ | | | | |
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twitter @theschlem? ? ??IG? @the_schlem? ? ? ?KE7AJZ
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Well, I have built a QMX after successfully building a QCX plus and a QDX. Got through the smoke test, and loaded the latest firmware. After uploading the firmware, the LCD came on and now the unit displays the splash screen with no responses to any inputs. Any ideas??
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The RX curent seems too low to me. I have no idea what is the unit to unit variation but mine takes 98mA at 9V with the backlight on. Without the backlight it drops by about 9mA if I recall correctly.
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Re: Reviving/Revisiting Damaged QDX - Troubleshooting advice needed
Charles,
I think that clock generator needs to be replaced.?
JZ KJ4A
On Sat, Aug 12, 2023, 10:04 PM Charles Johnson < cjohnson@...> wrote: To all,
My apologies for the large type in my previous post. I wrote it in the Notes app on my iPad and when I copied and pasted it, despite my best efforts, I couldn't make it smaller :-/
Regards,
Charles Johnson
KF4AYT
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Re: QMX Poor contrast with backlight on
Yes, I have the trim pot turned full left (counter-clockwise). That's the only position that gives legible contrast.
And it looks like I was premature in saying the problem has worked itself out. After starting up from being turned off several hours, the backlight is back to giving crappy display contrast. It looks like if I turn the backlight on while the QMX is transmitting, the screen can flip back to having good backlit contrast.
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Re: Reviving/Revisiting Damaged QDX - Troubleshooting advice needed
To all,
My apologies for the large type in my previous post. I wrote it in the Notes app on my iPad and when I copied and pasted it, despite my best efforts, I couldn't make it smaller :-/
Regards,
Charles Johnson
KF4AYT
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Hi John
Please post your Basic code that is creating an error? here, and the error code are you getting, and I will try and duplicate it and look for a solution.
Dave VE3KCL
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Reporting back.
I needed to raise the audio gain in the QMX band configuration menu from 54 to 60 to get about 30dB noise floor on an empty waterfall (WSJT-X reports 32dB).
Now when I record on a busy waterfall (WSJT-X reports the loudest decoded signal at +6dB) the maximum absolute value is 569.
So the audio dynamic range is still around10 bits.
This is probably about right when the audio device is 16 bits, but for a 24-bit audio device it seems low.
That said, I'm getting 25 decodes per interval on 20m right now so in reality there's not much to complain about!
Thanks, Hans!
73, Mike KK7ER
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Re: QCX Speaker recommendations needed?
Many 40mm DIA 32 ohm speakers available on Amazon:? Search on?
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Re: QMX Poor contrast with backlight on
Weird.? Have you tried adjusting the blue pot to the left of the screen, regardless?
Jason / K1LOL
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Re: Unusual Start Up Current
#qmx
Hans took the time to created a great QMX schematic on the QRP Labs website including component numbering which corresponds to the page number of the schematic. For those of us trying to help and to follow the posted information flow, it would help if everyone please double checks the component numbers they use to describe the problem/fix.
73 Kees K5BCQ
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Hi Hans,
> It's 6dB per bit. So 45dB would be 7.5 bits. Not 15.
You're right, of course, about the 6dB per bit.
But I think Audacity may be confusing things a bit (seems to me that Audacity is off by a factor of 2).
Let's look at it a different way.
The maximum absolute value of the samples in the 24-bit PCM wave file recorded on the QMX is 389.
Therefore the entire wave file has a 10 bit dynamic range (all values fall within [-512,511] so are representable using 10 bit signed integers).
That leaves us with 14 bits to spare.
So there really is a lot of headroom here.
Whether or not we are missing FT8 decodes due to quantization error depends on the RF noise floor as well as quantization noise floor.
But it sure seems possible to me that we could be missing decoding some of the weaker signals.
I'd love to know the dynamic range you and others are seeing on the QMX with default gain of 54.
My Windows audio device gain is set to 100% for the QMX audio device.
I'll play around with the gain value in the QMX configuration screen and report back.
73, Mike KK7ER
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Re: Unusual Start Up Current
#qmx
Mystery Solved:?
Bad Q505 (BS170) was conducting when off.? During startup, before the first transmit,? the PA voltage control provides full voltage to the PA transistors even though the QMX is in receive? (this is a firmware anomaly).? This was the cause of the extra current.??
Replacing the bad BS170 corrected both the startup current and low transmit power.
Also, I did check the transition from the 3.3V linear and the buck regulators which was correct.
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Marek, did you install the jumper between the two points labeled “28”?
Ron
On Sat, Aug 12, 2023 at 15:02 Marek SP9TKW < sp9tkw@...> wrote: Hi All,
I'am still unable to get good RF sweep in my QMX, 9V version 55mA RX 3-4W output into dummy load, but receive is very quiet. I presume this is due to BPF.
All continuity checks are OK. Here are my sweeps as well as picture of L401, link between 28t and last is on another side of the board. Any pointers or suggestions will be greatly appreciated.
---------------------------------
73 de Marek SP9TKW
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I just submitted a ticket for a missing microphone.? I was lucky enough to be missing a part that doesn’t matter right now! ? Mike WM4B ?
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From: [email protected] < [email protected]> On Behalf Of Jim Bennett / K7TXA via groups.io Sent: Saturday, August 12, 2023 6:36 PM To: [email protected]Subject: [QRPLabs] QMX Part Missing ? Sad to report that my QMX kit is missing the BN43-1502 (T507) binocular core. Hans - please do your magic and see if one of your staff can get one to me.
In the mean time I can continue at step 2.15 and revisit? T507 when the part arrives.
--
Jim / K7TXA
Eagle, ID
SKCC 10447
BUG 301
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Todd Schlemmer
VE3KCL
Mark K9TR
Ronald Taylor
Mike Besemer - WM4B