Re: Solder iron tip recommendations
Steve,
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I am building a QMX+ and doing well with a 1 mm chisel tip on my Hakko. I think that I read something from Hans saying that the board design matches well with a 1 or 2 mm tip. I’ve completed all of the discrete components and most of the wound toroids and it has gone smoothly compared with a QDX-M that I built with the “wrong“ solder and tip.?
You may want to scroll through /g/QRPLabs/message/128792 and my post there regarding other factors besides tip size and shape.? 73 de Joe KA1ZNA
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Re: QMX Rev 4 mid-band schematic / L405a and L405b connected to GND
I'm building this version soon as well, I've been thoroughly going over the manuals and videos. Do you mean L405a and L405b? I've noticed the R4 manual refers these toroids as L401a and L401b in the beginning (maybe because it was a single L401) but then later calls them L405a and L405b.?
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QMX Rev 4 mid-band schematic / L405a and L405b connected to GND
Hi all, I am building a mid-band Rev 4 QMX. After installing the L502 toroid, I checked some connections using a continuity tester and noticed that all leads connected to L405a and L405b are connected to GND. This seems suspicious to me, as the assembly manual shows on page 37 that the toroids are connected to RF IN, so I wanted to check the Rev 4 schematic. However, I could only find the Rev 3 schematic on the QRP Labs website, without a mid-band version.
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Any pointers regarding this?
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Thanks, 73
Donat HA5MZX
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Re: SWR Protection QMX mini
Depending upon the core size and type, yeah, heating at 5w is a thing. Especially w/ EFHW antennas.
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Al, K2ZN
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Re: QMX+ V2 - I've killed it
It does sound like maybe some mechanical flexing in the PCB could of shorted something out to the chassis.
I would suggest pulling the board out of the case and looking at it from the side to see if you have component leads that are too long and the board flex put them in contact with the chassis, creating a temporary short that killed something.
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Since we install our own inductors, transformers and transistors the lengths of the leads are left up to us to cut flush enough to not get near the chassis. It is also possible that the flexing broke free a component, solder joint or trace.
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A make-or-break electrical transient seems unlikely and if that did happen it might harm some of the start-up circuitry, switching supply or regulators.
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I have an Acer laptop that has that very problem with their poorly designed power connector on the back, I now need to heat gun off the surface mount connector and put a new one on the laptop (PITA).
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Tisha, AA4HA
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Re: SWR Protection QMX mini
Then we're back to: is there any way the transformer could be overheating. It seems unlikely, but so far, it's the only thing I've personally seen in the wild that leads to the specific symptoms you describe.?
For example, using the Chameleon Hybrid Micro, if I forget that it's only rated for 20W continuous digital mode use, with a 100W radio where I forgot to dial back the drive. It'll work for a while, and then I can watch the SWR slide upward in the course of a 15 second FT8 cycle.
Again, it seems unlikely when we're only dealing with 5W max, but...
On Fri, Sep 20, 2024, at 10:28, Jack Kibelbek via groups.io wrote:
That was a typo. It is a proper 49:1 UnUn.?
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Re: SWR Protection QMX mini
That was a typo. It is a proper 49:1 UnUn.?
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Now I remember, I was hoping to use this to provide 20 volts for the qrp labs 50 watt amp from a 12 volt battery. Do you guys think it will work ? Paul K2DB?
I cannot remember when I purchased these or why I purchased these and I don't remember what purpose I purchased these.Can anybody help me out?I have two of them. PAUL K2DB
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Hi Paul
Google image search
73 DE muhsin TA1MHS
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Re: BS170 Heat flow experiment with results (Updated)
I ran tests with fiber washer/nylon screw and also with metal washer/metal screw. I also ran the TN0110.
Some experimental noise is evident I think but it is too big of a pain to redo everything. Hopefully some useful insight can be gained from this.
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| Temperature rise at center of identical heatsinks in degrees C |
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| attached to the respective location |
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Case |
Drain |
Source |
Gate |
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total |
| BS170 max heatsink |
4.5 |
3.7 |
2.4 |
1.9 |
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12.5 |
| BS170 Fiber Washer |
3.8 |
2.4 |
2.1 |
1.4 |
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9.7 |
| BS170 Metal Washer |
3.1 |
2.5 |
1.8 |
1.3 |
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8.7 |
| TN0110 max heatsink |
4.1 |
3.2 |
1.6 |
1.4 |
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10.3 |
| TN0110 Fiber washer |
3.3 |
3.3 |
1.6 |
1.4 |
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9.6 |
| TN0110 Metal Washer |
4 |
3.6 |
1.8 |
1.5 |
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10.9 |
| TN0110 Reverse metal washer* |
3 |
3.8 |
1.6 |
1.6 |
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10 |
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| *Flat side against washer, round side against heatsink |
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Tony
AD0VC
toggle quoted message
Show quoted text
Very nice experiment, Paul
Nice to see some real experimental data.?
I agree with Paul AI7JR, it would perhaps be interesting to measure with only the flat of the transistor face against the copper, since practically in a transceiver the curved part of the body is not touching the copper. I don't
think there's any problem with the?measurements though; all the copper plates are the same size with the same dissipation to the environment so it's a reasonable relative comparison.
73 Hans G0UPL
On Thu, Sep 12, 2024 at 7:47?AM Paul - AI7JR via ?<paul.hanchett= [email protected]> wrote:
I wonder if it tells what we want to know...
"Wrap the BS170 case with copper tape and solder it to another copper plate."
In the QMX, only the flat side is connected to the heat sink... (Assuming the washer and screw aren't very significant!) If that were taken into account, heat extraction via the case and via the drain lead might be more comparable, maybe even swapped?
You're making the assumption that temperature at the measurement point is a proxy for power flow on the path. But the actual temperature is a function of the thermal resistance from the measurement point to the environment...
It seems to me that you'd need to standardize the thermal resistance of what you attach the measurement points to, in order to measure relative power flow.
This is giving me a headache! Am I making it harder than it has to be?
Paul -- AI7JR
On 9/11/24 20:42, Sandy via ?wrote:
Hey Tony - That is an interesting result. There is no substitute for actual measurement. This suggests that case contact with the pad is important. I always install the BS170s first with the screw and washer ensuring they are all flat and only then solder
in place. Thanks for your efforts! Sandy KB3EOF
On 9/11/24 22:18, mux_folder2001 via ?wrote:
I have attached a PDF file that describes an experiment with the goal of determine where the heat flows in a BS170. The PDF contains pictures of the fixture and a graph of the results. The essence of it is that, given equal opportunity, heat will flow as follows:
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Best flow is through the case.
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Second best flow is the drain lead.
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A distant third is the source lead.
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Last is the gate lead.
The graph will give you a sense of how much difference there is between them.?
The transistor is configured in a DC circuit and is dissipating 767mw continuously in the test. I should have put that in the PDF file but I forgot to.
Tony
AD0VC
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Paul -- AI7JR
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Apparently, I'm learning to understand what I see when I just see a board like that. I'd made a bet with myself that it was a boost or buck/boost.
Michael WD0OM
On Fri, Sep 20, 2024, at 09:36, Graham Whaley wrote:
stick 'A1401220' in google, and it will show you they are 250w 10A 8.5-48v DC-DC boost converters ;-)
73,
?Graham, 2E0WRW
On Fri, 20 Sept 2024 at 15:32, K2DB Paul Mackanos via <paul.mackanos= [email protected]> wrote: I cannot remember when I purchased these or why I purchased these and I don't remember what purpose I purchased these.Can anybody help me out?I have two of them.
PAUL K2DB
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stick 'A1401220' in google, and it will show you they are 250w 10A 8.5-48v DC-DC boost converters ;-)
73, ?Graham, 2E0WRW
On Fri, 20 Sept 2024 at 15:32, K2DB Paul Mackanos via <paul.mackanos= [email protected]> wrote: I cannot remember when I purchased these or why I purchased these and I don't remember what purpose I purchased these.Can anybody help me out?I have two of them. PAUL K2DB
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All you need are USB A to C cable and an Iphone camera adapter. Works well with my QMX (not plus). Also have used it with a trusdx, USB audio adapter and iphone camera adapter and also?a QCX/USDX.?VOX is required if all cases.?
On Friday, September 20, 2024, 6:50 AM, Mike Black via groups.io <mdblack98@...> wrote: It's a 1-time $1.99.
And what virtual USB port are you talking about?
The app gives 3 choices
#1 Hold the? phone up to the radio (yuck!) #2 Build a custom cable to hook up audio to your headset jack #3 Use a Digilink Nano or Signalink and a USB adapter for your IPad or IPhone and make sure it can provide enough current to power the Digilink/Signalink
Mike W9MDB
On Friday, September 20, 2024 at 07:50:11 AM CDT, Luis Rogelio Galina <lu4hk@...> wrote:
Has anyone had experience with QMX + iFTX with the virtual USB port?
The costs that apply US$ 1.99 are annual or monthly, I can't find this thread on my iPhone
72 Luis
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Jginaz
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I cannot remember when I purchased these or why I purchased these and I don't remember what purpose I purchased these.Can anybody help me out?I have two of them. PAUL K2DB
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Re: QMX (not-plus) power issue
I did actually take the QMX apart after I posted, as much out of curiosity as anything else -- I am building a QMX+, but had not actually looked inside the QMX since I bought it used, already built. It was instructive in general. I didn't see anything obviously bad about the solder joints, but I didn't look too closely at specific components like the 20/30 LPF.?
I did not try different cables or connectors for the simple reason that I don't have any. I have exactly one short jumper right now, about 3', and it's brand new. It's UHF male on both sides, so I'm using an elbow coupler to the radio, of which I also have exactly one (coupler, that is, not radio, qv) at this time. One has not had so much time in this hobby as to have acquired lots of spares, yet.
I do see the same result on the diagnostics connecting the dummy load directly to the coupler, though.
I do have other radios whose performance is known and trustworthy that I can test -- I just didn't have time to fetch them to my makeshift work space last night (I also have neither a shack, nor a proper workshop), but testing the power meter against one of them is on my list. I also do have local people who can help me out if need be.
Michael WD0OM
On Fri, Sep 20, 2024, at 08:17, Greg McCain via groups.io wrote:
Just some quick thoughts on your observations.
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RE: low watts out on 30/20.
They share the LPF pair.
Inspect solder joints, turns on the toroids, capacitors etc.
Fiddle with spreading and squeezing turns on those two as well.
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RE: power output differences
Have you tried different interconnect cables or BNC couplers?
Do you get the same results on the diagnostics with just the dummy load connected to the QMX? Try with both interconnect cables and/or BNC couplers.
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Any chance you have a nearby Ham Buddy that can check the new power meter. Or perhaps you have another radio you know works well?
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Hope it's something simple since the new power meter seems to be showing just about 1/2 of the expected power out?
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Re: QMX (not-plus) power issue
Yeah, I realized that after I'd posted, then felt dumb about it. I did take a moment to zero them out. It did not really change the output result, of course.
On Fri, Sep 20, 2024, at 06:46, Donald S Brant Jr wrote:
On Thu, Sep 19, 2024 at 10:22 PM, Michael - WD0OM wrote:
with what look to be calibration screws under the needle display.
Those are usually mechanical meter zeroing adjustment screws, for zero setting, not calibration.
73, Don N2VGU
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Re: QMX (not-plus) power issue
Roy:
I did in fact post that it was a 12V QMX. I did not build it, however; I bought it from someone else who had.
I have to admit I had forgotten to pay attention to what the power source (an Anker power bank + 12V trigger cable) said my current draw was. That had come up before, so that's an oversight I should correct next time I get a chance. I do suspect it's higher than it should be, though. While I was using the power bank to also run the laptop (long story), that should not have drained this particular power bank to zero in the time I was using them; but it did.
Still, I should check the numbers. Not sure when I'll get a chance to do that experiment next, but I'll report back when I do.
On Fri, Sep 20, 2024, at 04:55, Roy - KI0ER wrote:
Some helpful numbers to post would be the voltage you built your QMX for, and what is the overall input current draw in receive mode of your QMX??
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For a 12v QMX you should see around 90 mA or so of current when it's on and idle (not transmitting).?
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If it's substantially more than 90mA then your power meter is likely correct, and one of the output power transistors is likely blown/defective.... As a first diagnostic guess.?
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73
de Roy - KI0ER
Littleton, Colorado USA
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Re: Thinking about a project, receiver module + VFO / sig gen
Thanks for the reference, Alan!
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Eric
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Re: W2LI Magnetic Loop Antenna - Anyone Use This?
Please see the 开云体育?
"loop Antennas" page...
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Best OM,
NZ8I
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It's a 1-time $1.99.
And what virtual USB port are you talking about?
The app gives 3 choices
#1 Hold the? phone up to the radio (yuck!) #2 Build a custom cable to hook up audio to your headset jack #3 Use a Digilink Nano or Signalink and a USB adapter for your IPad or IPhone and make sure it can provide enough current to power the Digilink/Signalink
Mike W9MDB
On Friday, September 20, 2024 at 07:50:11 AM CDT, Luis Rogelio Galina <lu4hk@...> wrote:
Has anyone had experience with QMX + iFTX with the virtual USB port?
The costs that apply US$ 1.99 are annual or monthly, I can't find this thread on my iPhone
72 Luis
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Joe AI5DD
Al Scanandoah
Tisha Hayes, AA4HA
K2DB Paul Mackanos
Charles Schuler