Re: QDX Atmel internally shorted
QCX is back up and running.? Built another QDX and it is functional.? I assembled a BPF buffer board and managed to keep all the magic smoke in all the components.? They say it comes in threes.? Hopefully I got all three out of the way.
Joshua.
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Re: #gdx QDX Firmware Request: Phase Modulation (psk31, etc.)
#gdx
Ed,
--/g/QRPLabs/message/94746
This gets covered often, like clockwork.
The answer is yes, you are missing the modulation scheme
of PSK31.
With a TX system that is NOT LINEAR, that being Class C, D, or E,?
PSK31 and similar cannot be done as the phase transitions would
create adjacent channel noise in the form of modulation clicks.? That
comes from the inability to recreate the amplitude information.
Allison
------------------
Post online only, please no email.
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Here is a link to a video I just uploaded to YouTube of my 50W Amplifier build for 40m
https://www.youtube.com/watch?v=Ru9cReq-_x4
--
de Tony, EI5EM
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Re: #gdx QDX Firmware Request: Phase Modulation (psk31, etc.)
#gdx
Ed,
unfortunately the filtering used in classic PSK31 results in
amplitude modulation of the signal at the phase transitions, as
noted at ,
and in page 3 of the paper you quoted. The filtering is necessary
to avoid adjacent channel interference. The amplitude variation is
a direct consequence of that filtering.
Why is this an issue for PSK31 but not for FT8? In FT8 FSK is
used, with filtering applied to the transitions between one
frequency and the next. That results in no consequential amplitude
variation.
There's a lot more that could be said, but that's the
essence of it. The compromise with the QDX is that it's very good
for FSK systems. [Constant amplitude PSK systems occupy far too
much bandwidth to be sociable.]
HTH, sorry to be the bearer of bad news, 73,
Robin, G8DQX
On 16/11/2022 11:49, Ed G8BQR via
groups.io wrote:
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Hi Hans,
Something else to put on the list of "wouldn't it be nice"
items for future releases of firmware.
psk31? "...............the "dots" of the code are signalled
by reversing the polarity of the carrier."[G3PLX psk31 pdf,
attached]
This requires the RF oscillator to make a programmed 180? RF
phase shift as well as an RF frequency setting, which seems
feasible, with the same type of amplitude management as for
frequency shifting.
However, the phase needs to be measured first :-)? this seems
to be the more interesting problem.
With RTTY at about 45 baud being achievable, PSK31 at 31
baud, and possibly PSK 63 at 63 baud may be feasible.
Is this a real possibility, or am I missing something ??
Regards,? Ed? G8BQR
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Re: QDX Firmware Request: LED brightness
Somewhere between the 70's and today, cheap LEDs went from soft, dimly-glowing indicators to a blindingly-bright illuminators even when intended just to be an indicator!
As Chris KC0TKS says, the good news is that massive increase in efficiency means a modern LED can make a good indicator running on just microamps.? Electro Bob wrote an article about the great utility of cheap T5 RGB LEDs that are good universal indicators when run in the uAmp range.? I've followed his advise and used a bunch in my projects.? https://www.electrobob.com/the-coolness-of-rgb-leds/
?- Bill? N3AJ
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Re: QDX LED Flashing Continuously
#qdx
Glad you got it figured out.
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On Nov 16, 2022, at 1:34 AM, Doug Kaye <doug@...> wrote:
?Problem solved! The QDX was simply demanding a firmware update and wouldn't get out of that mode. I downloaded the latest firmware, dragged it to the QDX "drive" and the firmware update started on its own. Once that was done, things came to life!
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Re: QDX Firmware Request: LED brightness
I unknowingly bought some "ultra bright" 3mm LEDs from Amazon. At "normal" LED currents, 10mA or so, they are so bright you cant even look at them, like staring at the sun. I experimented with dropping resistors and went as far as 120k @3.3v and they still emitted a usable amount of light! Do the math on that one, a handful of microamps!
My point being that Alan is correct, if you get the ultra-bright LEDs and hang a high value dropping resistor on it, I think you could connect an LED to anything, anywhere in the QDX without worries.
73, Chris - KC0TKS
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Re: QDX Firmware Request: LED brightness
On Wed, Nov 16, 2022 at 07:03 AM, cris blak wrote:
I've replaced the original red LED with a green one.
?Chris,? That's a good color, too! On other QRP Labs projects I've used a blue LED and have been happy with the way it looks. Blue was used a lot for power indication; now it seems white is preferred.? I'll see what I've got in my parts bin. Green sound good! --Al
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Hi Paul,
Thank for the feedback. That means the error still present! I have ver3 with 1_05 but never run the test (by the way I have also an SA44 analyzer). When you have time to redo the measurements it will be nice if you can quantize the errors due to this bad frequency shift! If it say 1% than not bother about it. Interesting subject. Maybe Hans could say more if it is interesting for him?!
73 de YO3FFF Cristi
Pe mar?i, 15 noiembrie 2022, 18:40:10 EET, Paul WB6CXC (wb6cxc.com) <paul@...> a scris:
On Mon, Nov 14, 2022 at 10:43 PM, cris blak wrote:
I'm interested what was the FW you used when you rung those measurements. I think Hans fix this issue in the last one (1.05 I believe). So please check.
My QDX firmware is v1_05, and the board is PCB Rev 4.? AFAIK this is all the latest, I ordered it in late October and received it from Hans the beginning of November.? I built it on Nov 5. About the FSK issue, I would like to try repeating the tests using a longer QDX frequency measurement period than the default 100 per second.? With the WSPR symbol rate being so slow there's no reason that it couldn't measure more audio cycles and get a more precise frequency measurement.? That way we could tell if the error is due to the measurement, or to the S15351 divider setting algorithm.? (Although I believe that Hans already knows which is the case, likely the divider setting).? Certainly the default frequency measurement method *should* provide far better accuracy that my measurements were showing. ? -- Paul Elliott - WB6CXC
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Re: QDX Firmware Request: LED brightness
Hi there,
I've replaced the original red LED with a green one. The light is lower now not bothering the whole room in the dark.
Try it.
73 de YO3FFF Cristi
Pe mar?i, 15 noiembrie 2022, 18:43:38 EET, Hans Summers <hans.summers@...> a scris:
Hello Al
Why not! Sounds fun! I will take care of it with some firmware changes and a few hardware ones in the next PCB revision.?
73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl
-------- Original message -------- From: Al Holt <grovekid2@...> Date: Tue, Nov 15, 2022, 6:08 PM To: [email protected]Subject: Re: [QRPLabs] QDX Firmware Request: LED brightness A Post-It bandaid...
--Al
WD4AH
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#gdx QDX Firmware Request: Phase Modulation (psk31, etc.)
#gdx
Hi Hans,
Something else to put on the list of "wouldn't it be nice" items for future releases of firmware.
psk31? "...............the "dots" of the code are signalled by reversing the polarity of the carrier."[G3PLX psk31 pdf, attached]
This requires the RF oscillator to make a programmed 180? RF phase shift as well as an RF frequency setting, which seems feasible, with the same type of amplitude management as for frequency shifting.
However, the phase needs to be measured first :-)? this seems to be the more interesting problem.
With RTTY at about 45 baud being achievable, PSK31 at 31 baud, and possibly PSK 63 at 63 baud may be feasible.
Is this a real possibility, or am I missing something ?? Regards,? Ed? G8BQR
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Re: QDX Firmware Request: LED brightness
On 16/11/2022 08:51, KEN G4APB wrote: the onboard LPF test points would not power leds directly, Ken I'd try high intensity with around 22K in series, still gives sufficient brightness to see indoors. About 100uA? Not sure if max "Output current sunk/source by any I/O and control pin 25mA" is relevant but 100uA is not going to break anything. 73 Alan G4ZFQ
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Re: QDX Firmware Request: LED brightness
While you are at it Hans.....
I often considered adding 3 leds to show which LPF has been selected in the QDX. Sometimes while diagnosing and the fact I am experimenting with different bands, sometimes I have set the Band Config wrong LPF for a band and wondered what has gone wrong. I presume the onboard LPF test points would not power leds directly, so a couple of extra drivers would be needed....just a thought.
73 Ken G4APB
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Re: QDX for 40-10m - Should I wait?
#qdx
Interesting, Hans, does going to T37-10 make a significant difference? I used T37-6 types from an LPF and get 5 watts at 21MHz but 3 watts at 28MHz (different no.of turns too).
73 Ken G4APB
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Re: #qdx #80m Are there pictures of the RF Filter Sweep anyplace?
#qdx
#80m
On 16/11/2022 05:26, Paul - AI7JR wrote: Here are scans off my QDX. I think the 40, 30, and 20m scans are plausible. Paul Looking at the dB scale 80m does not look bad, others have posted similar. 60m was not at first included in the QDX spec. It was only added when it was pointed out that it worked and the harmonic suppression was adequate. It uses the 40m BPF and LPF. I always reckon to try before modifying. At 60m 15dB attenuation may be acceptable. Does noise level increase when a tuned antenna is connected? Does it receive well? If it really worries you then adjustment of the BPF will make 40m look worse. 73 Alan G4ZFQ
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Re: QDX LED Flashing Continuously
#qdx
Problem solved! The QDX was simply demanding a firmware update and wouldn't get out of that mode. I downloaded the latest firmware, dragged it to the QDX "drive" and the firmware update started on its own. Once that was done, things came to life!
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Re: QDX LED Flashing Continuously
#qdx
Interesting thought, Milt. I decided to try a good, trusty bench supply set to exactly 9vdc. Very clean output. No change, unfortunately.
?
? ? ?…doug K6DRK
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Re: #qdx #80m Are there pictures of the RF Filter Sweep anyplace?
#qdx
#80m
Here are scans off my QDX. I think the 40, 30, and 20m scans are
plausible.
I have my doubts about the 80m and 60m scans though--especially
the 60m scan!
?Any opinions?
Thanks,
Paul
On 11/15/22 08:49, Alan G4ZFQ wrote:
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On
15/11/2022 02:37, Paul - AI7JR wrote:
Are there RF Filter Sweep screen shots for
80-20m posted some place?
Paul,
The home page shows a 40m scan. Hans
posted that with no comment, presumably acceptable.
Many people have included scans in their posts better than that
and expressed dissatisfaction. I'm not sure what to aim for, some
have fiddled with the coil spacing and capacitors to make the
traces look good. Maybe they improve performance, I'm not sure
anyone has proof.
73 Alan G4ZFQ
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Re: QDX LED Flashing Continuously
#qdx
Doug,
Is it possible that the power supply is “hiccuping” during turn on?. ?This would make the QDX think that you are trying to go into firmware update mode. ??
Have you tried turning on the power supply with the QDX disconnected, and then connect the QDX after the supply has completely settled?
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On Nov 15, 2022, at 6:25 PM, Doug Kaye <doug@...> wrote:
?One other clue: QDX does appear as an external disk drive in the Mac OS Finder. But unlike the documentation, I don't see the EPROM or firmware files. The drive appears a empty. The drive appears as a 4MB MS-DOS FAT16 disk.
? ?...doug
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Re: How do yiou know your ground is any good?
Thank you Colin, this is just what I was lookkng for, though it’s still a litttle opaque, at least it gives md a starting point!
73, Willie N1JBJ
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On Nov 15, 2022, at 2:28 PM, Colin Kaminski <colinskaminski@...> wrote:
?I know nothing of the source, but I found these test methods interesting:
--
Colin - K6JTH?
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Joshua KJ7LVZ
Tony EI5EM
Paul - AI7JR