Re: W2LI Magnetic Loop Antenna - Anyone Use This?
Hi , update to my update.
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The W2LI does work well for a “compromise” antenna.
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In testing, it sends and receives decently on 40, 30, 20, and 17 meters using 5 watts on WSPR. ?Good SWR on all 4 bands too.
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Less traffic on 30 M, but that might just be who was on what bands when I tested.
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Soon, once my CW is competent, I will provide a report on performance with that mode.
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John - W3JED
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For Hans - QMX+ Capacitor Question
Good afternoon Hans,
Any guidance on my previous question from yesterday about the 33pf C402 capacitor being marked as 33K as opposed to 330 or 33J as noted in the parts listing?
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It metered out on my uncalibrated DMM at 36p.
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Hoping to get started today on assembly.
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Thanks in advance.
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GREG KI4NVX?
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Re: How much heat is "a lot"
If you apply some background heat to the bord, like putting it on a hot plate or using? hair dryer or heat gun, it will make it easier to manage the rework.
Don't worry about reflowing the other components unless you go crazy with a heat gun.
73, Don N2VGU
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QMX+ Rev 2 - Schematic request
Hi Hans
I know the differences to revision 1 of the QMX+ main broad are not much, basically the power boards are now include in the main board, but still for coherence is it possible to get the schematic for the rev 2 of the QMX+ board.
This is not a urgent request, take your time!
73 Azgael
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Re: How much heat is "a lot"
I have two Solomon soldering pencils that I use regularly, one has a very small chisel tip and the other has a much larger maybe 3/16 inch tip. ?The larger tip is what I need for BNC and other bigger connectors. ?You need to transfer much more heat to the larger parts and quicker. I keep both pencils set as hot as they can be set. ?When I solder it’s get in, apply heat, and get out when I see the solder melting and flowing. ?I just can’t see using the small tip that I use for through hole and smd parts for larger parts that suck heat away quickly. I would be applying heat forever and still not be sure the solder had flowed through the board and securely bonded the part. ?You need two different size tips. Be the REASON someone smiles today.
Dave K8WPE
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On Sep 23, 2024, at 11:08?PM, Karl via groups.io <karlshumaker@...> wrote:
? The dc jack is easy compred to the RF/BNC connector. Hans says you don't have ti fill the holes up just make the connection. I set my iron to 840°F stuck the point of the iron in one hole with the pin on the side of the iron point and counted slowly to ten. Then fed in som 63/37 tin/lead solder .6 mm diameter. Then you make sure it is flat on the board and square with the edge before you solder the other lead(s).
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The BNC connector the same but do the center pin first since it is real small. Same deal as before, but make double sure the barrel of the connector is parallel with the board and square. I recommend get that center pin then slide the board in the bottom half of the case and put the rear plate on to check the fir. Adjust as necessary.
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When Hans says "staight and square" he is serious. When he says get that audio sub board flat up to the main board he is serous too. But there do the one, maybe two pins and line it up with the front panel to make sure it is gonna fit.
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73
Karl
KI4ZUQ
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Re: How much heat is "a lot"
General points
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The ideal soldering process is fast heating of all the parts to be soldered and application of sufficient solder to the joint?
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Few electronic components can survive 350C for long so the key is momentarily hot leads but only warm device, Hardware like ?RF sockets can take some more heat/time but will still degrade if cooked enough
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That all means (ideally !) a relatively big bit (most beginners are surprised by what pros use on tiny circuitry) with a lot of metal near the tip on a powerful 90W thermostatic iron.
With more experience you may manage with smaller or less powerful but many beginners fail that way and don’t realise why. ?
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Tin the iron lightly. ?That solder film is critical to heat transfer
Plant the ‘big’ iron bit firmly on the biggest (thermal mass surface) wait a second or so for challenging jobs then roll the bit to also heat the smaller mass (eg PCB) ? When experience says it’s right add solder to the larger thermal mass then check it pools to the smaller , watch how the joint forms ?and let it cool. ?Always ?add the joint solder to the parts not the iron. ?
Don’t pour solder down the hole - it will run out the bottom and create impossible to see shorts. ?Apply the right amount of solder and STOP!?
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Typical wire component to PCB joints will be complete well within 1 second done right
More challenging tasks (metal cases items to large ground planes etc) ?do take longer but 10 secs is a lot and suggests a better technique as above is needed to ?heat the biggest problem without frying the other parts?
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Hi,
if this is in the situation when the PTT is activated it is possible that the T/R switching is not working correctly.
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73 Bojan S53DZ
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You’re going to have to be clearer about your set up?
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if you’re saying an unpowered or powered 50WPA connected to the QMX+ makes it oscillate (in TX) when an antenna doesn’t the first thing to check (with a VNA) is the amp input impedance
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But then you say nothing on RF in it RF out (do you mean it’s oscillating when PTT active and otherwise disconnected (not entirely surprising - Put a 3dB attenuator on the open input)?
Please set out the exact layout and conditions that trigger your problem -?
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Re: QRP Labs Turkey Workshop?
Great idea but already booked for this year. I'll be in hospital for an op in October LOL!
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Re: QMX Rev 4 mid-band schematic / L405a and L405b connected to GND
Hi all
L405a and L405b on QMX was an error in my documentation, it should be L401a and L401b. I have corrected it in the latest assembly manual I just uploaded now.?
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Hi All,
I just finished the build of the PA, and after adjusting bias tested it connected to dummy load, driven by QMX+. The QMX goes into protection mode.
Looking at the circuit with oscilloscope I can see that there are oscillations in the area (junction D3 - D5 - Q3 - R8)
Unmounted Q3 for now and replaced Q5 & Q6. Still oscillation.
Nothing on RF in - RF out, so ignoring the “RF amp” portion for now.
Inspected solder point etc but everything looks good.
Anyone had similar experiences or ideas for troubleshooting?
Regards
Jonas
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Re: How much heat is "a lot"
The BNC jack I was prepared for -- I've built two antenna kits with BNCs and those jacks just suck down SO MUCH HEAT. The DC jack, I probably should have been prepared for :-D
I never doubted Hans, I assure you. I'm just kind of klutz :-D
On Mon, Sep 23, 2024, at 22:08, Karl via groups.io wrote:
The dc jack is easy compred to the RF/BNC connector. Hans says you don't have ti fill the holes up just make the connection. I set my iron to 840°F stuck the point of the iron in one hole with the pin on the side of the iron point and counted slowly to ten. Then fed in som 63/37 tin/lead solder .6 mm diameter. Then you make sure it is flat on the board and square with the edge before you solder the other lead(s).
?
The BNC connector the same but do the center pin first since it is real small. Same deal as before, but make double sure the barrel of the connector is parallel with the board and square. I recommend get that center pin then slide the board in the bottom half of the case and put the rear plate on to check the fir. Adjust as necessary.
?
When Hans says "staight and square" he is serious. When he says get that audio sub board flat up to the main board he is serous too. But there do the one, maybe two pins and line it up with the front panel to make sure it is gonna fit.
--
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Re: QMX doesn't receive on 20-15
#qmx
On Wed, Sep 18, 2024 at 09:18 PM, Josefski wrote:
I was able to narrow the problem down to IC402. When I bypass it by disconnecting it from the mixer I can receive on 20 meters again. I've ordered a new part and will solder it in when it arrives to see if that fixes the radio.?
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I had the same problem, I replaced IC402 and everything became normal. I think if you use PA50, then IC402 will definitely burn out again. I use PA50 with 15 volts
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Re: How much heat is "a lot"
Thank you. I was afraid that would be the answer, and I'd already started in on desoldering before getting it. An absurd quantity of flux and desoldering wick later, the one really bad one is repositioned and the back plate fits (I checked before even contemplating resoldering). Probably I oversoldered the joints, on top of it all, because man alive did it take a lot to undo it!
On Mon, Sep 23, 2024, at 21:59, Stan Dye wrote:
Desolder all but one terminal completely.?? Then heat the last soldered terminal while pressing the part to the board with your finger.? As the solder melts, you can position the part with your finger pressure.? Then remove the iron.? The one terminal will hold it in place while you solder the others.
OK, change in question: I managed to get the components soldered...but sure enough, the audio jacks are neither of them quite flat to the board. :-(
What's my best strategy for rework? Desolder them completely (if I can) and secure them properly with a rubber band or something next time?
/m
On Mon, Sep 23, 2024, at 20:38, Michael - WD0OM wrote:
I've got to the point where I'm trying to install the rear-panel connectors on my QMX+, and here is where my novice status as a solderer shows the most:
Just how much heat and time is "a lot". Because the DC jack (which is perhaps foolishly where I started, but it is listed first) is laughing at me! :-)
Michael WD0OM
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Re: How much heat is "a lot"
The dc jack is easy compred to the RF/BNC connector. Hans says you don't have ti fill the holes up just make the connection. I set my iron to 840°F stuck the point of the iron in one hole with the pin on the side of the iron point and counted slowly to ten. Then fed in som 63/37 tin/lead solder .6 mm diameter. Then you make sure it is flat on the board and square with the edge before you solder the other lead(s).
?
The BNC connector the same but do the center pin first since it is real small. Same deal as before, but make double sure the barrel of the connector is parallel with the board and square. I recommend get that center pin then slide the board in the bottom half of the case and put the rear plate on to check the fir. Adjust as necessary.
?
When Hans says "staight and square" he is serious. When he says get that audio sub board flat up to the main board he is serous too. But there do the one, maybe two pins and line it up with the front panel to make sure it is gonna fit.
--
73
Karl
KI4ZUQ
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Re: How much heat is "a lot"
Desolder all but one terminal completely.?? Then heat the last soldered terminal while pressing the part to the board with your finger.? As the solder melts, you can position the part with your finger pressure.? Then remove the iron.? The one terminal will hold it in place while you solder the others.
OK, change in question: I managed to get the components soldered...but sure enough, the audio jacks are neither of them quite flat to the board. :-(
What's my best strategy for rework? Desolder them completely (if I can) and secure them properly with a rubber band or something next time?
/m
On Mon, Sep 23, 2024, at 20:38, Michael - WD0OM wrote:
I've got to the point where I'm trying to install the rear-panel connectors on my QMX+, and here is where my novice status as a solderer shows the most:
Just how much heat and time is "a lot". Because the DC jack (which is perhaps foolishly where I started, but it is listed first) is laughing at me! :-)
Michael WD0OM
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Re: How much heat is "a lot"
OK, change in question: I managed to get the components soldered...but sure enough, the audio jacks are neither of them quite flat to the board. :-(
What's my best strategy for rework? Desolder them completely (if I can) and secure them properly with a rubber band or something next time?
/m
On Mon, Sep 23, 2024, at 20:38, Michael - WD0OM wrote:
I've got to the point where I'm trying to install the rear-panel connectors on my QMX+, and here is where my novice status as a solderer shows the most:
Just how much heat and time is "a lot". Because the DC jack (which is perhaps foolishly where I started, but it is listed first) is laughing at me! :-)
Michael WD0OM
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I've got to the point where I'm trying to install the rear-panel connectors on my QMX+, and here is where my novice status as a solderer shows the most:
Just how much heat and time is "a lot". Because the DC jack (which is perhaps foolishly where I started, but it is listed first) is laughing at me! :-)
Michael WD0OM
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QDX HB 20m RF filter sweep is very high
Just built my Rev 4 QDX HB (12V) after it has sat in the box for a couple years or more. Am doing initial testing. My RF filter sweeps look pretty good for all bands except 20m... there is actually a dip in the sweep at 20m, and it peaks at about 17.5 MHz. I see some old posts about this being relatively common but I didn't find any follow up.
Is this normal? Is there a fix that I am missing?
73, Steve AK0M
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Re: Still no output on QMX
Good to know! Thanks!
73, Paul -- AI7JR
On 9/23/24 11:39, Donald S Brant Jr via
groups.io wrote:
On Mon, Sep 23, 2024 at 02:18 PM, Paul - AI7JR wrote:
In general, how do changes in input voltage affect
the efficiency of a typical buck/boost supply?
I am not a power supply expert, but from what I have seen, the
efficiency seems to be more related to load current, with a
broad peak and a shallow falloff, and fairly insensitive to
input/output ratio, but typically above 90%.
73, Don N2VGU
--
Paul -- AI7JR
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John Dusek
Donald S Brant Jr
David Wilcox K8WPE
Bruce Akhurst
F4WCV
Nurlan
Karl
Paul - AI7JR