Re: Power supply recommendation wanted
I have the same "Korad" supply. It's been going strong for several years now. The supply limits voltage across its output transistor by switching between several taps on its supply transformer using a relay. I have had to replace that relay one time, I believe an inductive spike killed it. But it has otherwise been performing fine. I've used it for everything from powering electronics to electroplating and anodizing.
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Re: QMX Shipped, panic stage
#qmx
As far as assembly goes - Yes, it is a challenging build. It's by far the densest PCB I have ever populated. You will need to be extremely diligent about avoiding solder bridges. Keep solder wick handy. Inspect all of your joints with a microscope or loupe. Many pads sink into a massive thermally conductive ground plane and you will need a hot, powerful iron with plenty of thermal mass to make good joints in them. Know how to identify a cold solder joint. The enamel on the thinner magnet wire used for filter toroids burns off just fine but the thicker magnet wire used for power magnetics will need to be sanded off. The assembly manual recommends installing through-hole caps/diodes/inductors before toroids, but I think I'm going to do the opposite with my second build attempt, I'll report how it goes. I think the density of that area will make it easier to put the big things in first, then work the smaller things in around them.
Optional steps not mentioned in the manual:
Add thermal paste between BS170 output transistors and the ground plane underneath.
Some builders of the previous generation QDX put a flyback diode across the equivalent of L502 in that product.
If you set a current limit on your power supply the first time you power up your QMX, don't forget to turn the current limit off before you transmit. :)
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Re: QMX Shipped, panic stage
#qmx
Billy,
There is bias in the list.? People that have problems make noise those that succeed can't be bothered.
So you see the disaster stories even if its a low percentage of the actual builds..
Do you self a favor, read the assembly manual before you get it. read it carefully?
and understand the assembly procedure.
--
Allison
------------------
Post online only, please no email.
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Re: QMX Shipped, panic stage
#qmx
As someone who is responsible for many of the negative messages -
People who are having no trouble with their radio are out there making contacts with it rather than logging into a forum and talking about it. I bought my kit on the strength of a recommendation from a friend who has never posted here. He's having a great time with his kit and I can't wait to get mine on the air with his, and when that happens I'll be too busy operating to post here too. Any forum is going to contain a disproportionately high number of people having problems, because those are the people who are going to have the spare time to go post in the forums about it.
Even though I feel some design decisions could have been made differently, the reason I even feel the desire to express that here is because I believe it is a fundamentally good, and worthwhile, product with one or two things that can be improved, rather than a lost cause. I'm sorry to have contributed to any perception otherwise.
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SSB instead of CW in the logbook
When operating the QMX, I noticed that with CW, the CAT control sets the SSB mode in the logbook and automatically enters 59 instead of 599 in the report. That's not good if you want to take part in a CW contest with the QMX. There are incorrect entries. ? 73 Reinhard DL3AS ?
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Re: QMX Shipped, panic stage
#qmx
Billy, Just as additional reassurance, I built mine carefully, following the assembly manual literally. Mine powered up and worked fine the first time. I love this radio.
-- 73 Michael N6QP Up in Thin R
-- 73 Michael N6QP Up in Thin R
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Re: QMX Shipped, panic stage
#qmx
I'll add that past the Q103/Q104 short, I directly contributed to
the eventual failure of my QMX.
When I fixed the short, the hot air gun dislodged a couple of
other parts, leaving my QMX turning on, but "strangely". While
fixing that "strangely", something else happened that might have
taken out the CPU (maybe an errant clipping stuck to the mother
board.)
That problem has to be classed as my error, not a
problem with the design!
As Hans says, "You can do it!" Proceed with requisite care!
73, Paul -- AI7JR
On 8/31/23 07:14, Hans Summers wrote:
toggle quoted message
Show quoted text
Hello Billy
1) You're reading the wrong messages. There have also been
several nice reports of success stories.?
2) You also need to remember that all mailing lists have an
inherent negative?bias, in so far as people are far more
likely to post about a problem they are looking?for help
solving, than they are when everything is fine. And rightly
so, since?with 7,541 members here on this group, if everyone
posted something when they were successful, and the fact we
shipped an average 800+?orders per month in the last 6 months,
many of which contain multiple kits, we'd soon be overloaded
with emails. So keep the misery posts in perspective.?
3) Bear in mind the only known issue is that the Q103/Q104
transistors on the 5V SMPS board are a little close together
and due to manufacturing tolerances, a proportion of boards
have unfortunately got a solder bridge between the two drains;
HOWEVER, we are already testing all shipped boards for this
fault and correcting it pre-shipment if we find it.?
4) Watch my "52-tips" video?
while waiting for your QMX to arrive.?
5) If you take care and observe all the precautions
mentioned, there is a VERY high probability of success.
Remember, component and manufacturing failures are rare. It's
largely in your hands!
6) You're a Texan. Texan's can deal with anything.?
On Thu, Aug 31, 2023 at
4:48?PM N5SE < bwmoore@...>
wrote:
Hans,
Received message my QMX shipped today. Thought I would be
excited. But instead, I am reaching panic stage. With all the
misery I have read in the last week, I figure my chance of
ever getting it to work is somewhat less than zero. Guess I am
looking for a little assurance.
-- Billy (N5SE)
N5SE
Billy Wayne Moore
7066 Shady Knoll Ln
Willis, TX 77318-6324
Phone: 936-537-2975???
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Re: QMX Shipped, panic stage
#qmx
Billy,
stay brave...
... take your time and you will get it done...
I am one of those who? - read the manual twice - took my time to build - did it step by step and everything went well!
No surprise with Hans excellent Manual and additional hints from this Forum...
There are to many reports about Problems, but you probably know: "A bad message is told/forwarded 7 time more offen as a good one"
(Hopefully understandable as i am not a native english speaker)
Take your time and enjoy the build...
73 Alex, DK4FT?
Billy,
You can do this!? Just be careful during assembly to 1) remove all the enamel from the toroid wires before soldering, 2) check the continuity between VCC, VDD, and +12 against ground prior to first power up, and 3) use a current limited supply until you're up to full voltage (9 or 12 volts).? Also, be careful when trimming wires on the bottom of the board.? I accidentally nicked C526 when trimming enameled wires from T507, and had to find and replace this capacitor.?
Enjoy this build, and take your time.
73,
Walt - KK4DF?
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Re: QMX Shipped, panic stage
#qmx
Billy,
as well as watching Hans' video, maybe look for the pinned comment that lists all the tips and what time they appear on the video.
I plan to have this list handy when I start my build.
73, Steve.
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Re: QMX Shipped, panic stage
#qmx
On 31 Aug 2023 at 6:48, N5SE wrote: Guess I am looking for a little assurance. -- Well, you had at least two VERY HAPPY builders reporting in the emails today ... don't be so negative !! Follow the instructions carefully and either use a ZM-2 or equivalent manual tuner to tune the antenna before going full power and many, many people have had good results ... remember, a chat group like this draws more calls for HELP than praise for success. Jim w2jc
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Re: Power supply recommendation wanted
On 31 Aug 2023 at 8:56, Shirley Dulcey KE1L wrote: Keysight is now the company that's most like the
original Hewlett-Packard who picks these oddball spinoff company names? imo, HP THREW AWAY their entire fabulous brand name and market confidence when they rebranded to 'Agilent' ...
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Re: QMX Shipped, panic stage
#qmx
Billy,
You can do this!? Just be careful during assembly to 1) remove all the enamel from the toroid wires before soldering, 2) check the continuity between VCC, VDD, and +12 against ground prior to first power up, and 3) use a current limited supply until you're up to full voltage (9 or 12 volts).? Also, be careful when trimming wires on the bottom of the board.? I accidentally nicked C526 when trimming enameled wires from T507, and had to find and replace this capacitor.?
Enjoy this build, and take your time.
73,
Walt - KK4DF?
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Re: #qmx video: 52 tips for building your QMX successfully
#qmx
Just one more comment on the excellent "52 tips for building your QMX successfully" youTube video: With regard to the BNC connector, if you test its output to ground, you will see a short even though there is no actual short on the BNC.? That's because T507, the VSWR Stockton bridge transformer, has a winding that goes directly from the output to ground.? Either just inspect the BNC connections carefully for any shorts or mount the BNC before mounting T507.? Note that the pad from the hot side of the alternate SMA pads is very close to one of the ground pads of the BNC so this is good to carefully inspect.
-Steve K1RF
------ Original Message ------
Date 8/27/2023 10:14:59 AM
Subject Re: [QRPLabs] #qmx video: 52 tips for building your QMX successfully
Hans says it’s best to do it as he shows in the video to keep the boards properly oriented. Looked really easy to do the way he demonstrated. It’s an ongoing process of finding the best solutions and updating the manual.?
Ron So to clarify - The manual at Rev H currently says to burn or drill out the center of the spacer nuts on the power board - That is no longer recommended according to the video?
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Re: QMX Shipped, panic stage
#qmx
Hi Billy, my QMX worked just fine from the first power up.! There are still a few bugs that Hans will smooth out over the next firmware updates.? AGC, eratic volume control...to mention a few..? ?but the rigi is a great piece of engineering,? fully useable. and will only get better. best regards Scotty
On Thursday, 31 August 2023 at 16:05:53 BST, Ken W4KAC <oldjoeclark@...> wrote:
Just take your time Billy.? I spent about an hour a night for nearly a week.? QMX #332 worked right off the bench with no problems. Go slow and double check everything as you go so there is no doubt.? ?I have made many CW contacts with it since late July including every contact for the NAQCC letter challenge, and the NJQRP Skeeter Hunt this past Sunday.? Chased lots of POTA and SOTA and had some ragchews with it in the meantime.? Great radio, and I can't wait to hit the summits with it as the wx cools down.? Good luck with yours.
73 Billy, and many thanks to Hans!!
Ken, W4KAC
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Re: 6 and 8m QDX prototype
This prototype can be used only on 6m! 6
toggle quoted message
Show quoted text
On 31 Aug 2023, at 15:03, Afghan Kabulldust via groups.io <kabulldust@...> wrote:
? Actually I stuffed up again. The 8/6m QDX LPF Is this? 6
On 31 Aug 2023, at 14:30, Afghan Kabulldust via groups.io <kabulldust@...> wrote:
? Schematic that was missed off last email
Next I’ll send the 80m only QDX 6 On 31 Aug 2023, at 14:18, Kabulldust <kabulldust@...> wrote:
<image0.jpeg>
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Bob, Jim, et al,
Further to the 8/6m prototypes I previously posted, I’ll now post the details of an 8m only prototype.
Schematic
Analysis
Implementation
BPF is 11t on an T50-6, squashed up so probably 12 loosely wound may do the trick and a 30pF cap
RF Filter sweep
TinySA measurement
Sent from my iPhone 6
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Pacific Antenna also offers a "Mini SWR Indicator Kit" for $5. Works great.
73 Kees K5BCQ
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Re: QMX Shipped, panic stage
#qmx
Just take your time Billy.? I spent about an hour a night for nearly a week.? QMX #332 worked right off the bench with no problems. Go slow and double check everything as you go so there is no doubt.? ?I have made many CW contacts with it since late July including every contact for the NAQCC letter challenge, and the NJQRP Skeeter Hunt this past Sunday.? Chased lots of POTA and SOTA and had some ragchews with it in the meantime.? Great radio, and I can't wait to hit the summits with it as the wx cools down.? Good luck with yours.
73 Billy, and many thanks to Hans!!
Ken, W4KAC
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Re: QMX Shipped, panic stage
#qmx
Billy, my QMX worked properly from the moment I fired it up. 100% smoke free! Just some minor screen issue that was my fault, and I soon corrected. One of my friends, who ordered a QMX kit two or three weeks ago, got his assembled and running last week, enjoying every step of the process.
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Re: 6 and 8m QDX prototype
Actually I stuffed up again. The 8/6m QDX LPF
toggle quoted message
Show quoted text
On 31 Aug 2023, at 14:30, Afghan Kabulldust via groups.io <kabulldust@...> wrote:
? Schematic that was missed off last email
Next I’ll send the 80m only QDX 6 On 31 Aug 2023, at 14:18, Kabulldust <kabulldust@...> wrote:
<image0.jpeg>
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Reinhard Gr?nz
Michael N6QP
Paul - AI7JR
GM0HUU Steve