Re: Hints for successfully building the QDX
It also says to cut the three lengths of enamelled wire to 20cm. I did this, then with the screwdriver turned it 60 times, to find it was only long enough to get seven turns, possibly eight with short tails, on the toroid. Luckily I had a?filter kit untouched so raided that to try again, making the lengths 30cm, and this time there was about 5cm sans tails over after the ten turns. It might be wise to put 25cm as the length in the manual as it's always easier to remove than to add ;)
Robbie M1ROK
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Re: Hints for successfully building the QDX
When soldering through hole leaded components i was taught to place tip of iron, pre tinned, to the pad first, wait for 3 seconds, slide iron to junction of pad and lead, apply solder then slide tip of iron up component lead and away.?
I cringe when I see soldering where both iron and solder are both applied at the same time and then both are immediately removed from joint.?
Andy?
--
The universe is made up of Protons, Neutrons, Electrons but contains only one M0RON.
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Re: Hints for successfully building the QDX
As excellent as Hans' build instructions are, I feel there is one page which could do with a bit of clarification.? That is the one dealing with winding the trifilar transformer T2.? It is absolutely critical that the start and end of the windings are identified along with the continuity checks with a multimeter. If you get a start of winding mixed up with an end, you will get no phase reversal going into the QSD inputs and it just won't work!? (Strictly speaking, this only applies to the centre-tapped secondary windings, the primary phasing is immaterial.)
I have roughly modified the pages from version 1.04 of the manual, to hopefully make this clear.? There's a couple of pictures attached...
--??
Peter Lee
G3SPL
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Re: Hints for successfully building the QDX
I reached stage 2.11 yesterday before other matters intervened, so hopefully today will be the day...
These hints may be blatantly obvious but here goes.
1.? My first step was to remove the four SMD inductors for no better reason than I could do it with the board flat on my work surface at that point.? Tweezers were helpful for two but the others came off stuck to the ball of solder on the tip of my iron
2.? If you are concerned about how much wire you need for T1, then wind L14 first and put it aside until needed.? Then you know how much you have left.? The inventory says 50cm is supplied, but the length in my kit was a generous 60cm and I had 18 cm (say 7") left at the end of my 3:3 transformer despite leaving longer tails than Hans suggests.? So you will have plenty.
3. I have several tips of differing sizes for my soldering iron, so I changed to a larger one for T1 and L14 for better heat transfer - there is room to wield a bigger tip if you are careful.? I also increased the iron temperature from my usual 350C to 390C (sorry, if you work in Fahrenheit ask Mr Google).? Seems to have worked as both passed their continuity checks first time.??
4.? If you are in the position of having to buy solder for the build, go for 0.5mm (0.02") or thinner rather than the more standard 0.7mm or thicker.? Although you can build successfully with the thicker solder, it needs more care as it's all too easy to use too much solder and create blobs and bridges.?
5.? I haven't got there yet, but if you do no other pre-switch on checks, at least check that you don't have a dead short on the DC input.? All I will say is that melting insulation has a smell of its own......
And a note for those who are concerned about such things, my QDX (order 50300) left Hans on Thursday 28th, reached his local TNT depot in Izmir around midday on Tuesday 2nd and was handed over to me in southern England midday on Wednesday 3rd.? So no complaints there.??
Good luck and enjoy the build.
Chris? G4CWS
??
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Pleased to report that my QDX is now also transmitting on 20/30 m.? Nothing beats old fashioned tracing of the circuit with an ohm meter to isolate and identify errors in eye - brain communication.? :)?? Here are readings using a Bird wattmeter with attached 50 ohm dummy load [neither calibrated by a certified lab].? Input signal is the tune function from WSJT-X Band? ? ? ? ? ? ? ? Power out [Watts]80m? ? ? ? ? ? ? ? ? ? 2.8 40m? ? ? ? ? ? ? ? ? ? 3.0 30 m? ? ? ? ? ? ? ? ? ?4.7 20m? ? ? ? ? ? ? ? ? ? 3.3 Perhaps the variation in power levels indicates a minor issue with the LPF - I have a nano-VNA and sets of good SMD caps, but I doubt if it's worth the time to investigate further.? [I checked all inductances with my L/C meter before installing the toroids.] I still find an interesting phenomena with FT-8 from WSJT-X in that I can receive/work DX stations on 20m but not local hams.? Weird.? They decode me without any difficulty... Looking into this more. Time to work on? 30m and 80 m antennas.? 73
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Hi Wes ? Syd, adding turns to a inductor used in a LPF will NEVER result in increased output. Take a look at the response curve for a LPF, there is a knee in the curve, below which there is full output, and above which the output reduces. All that happens when you add turns is the knee frequency decreases, when you remove turns the frequency increases.?
Respectfully I disagree... What?really happens in practice is that quite often you find that increasing the inductance does increase the output power. I see this all the time. *IF* an LPF is perfectly designed and perfectly?constructed with perfect components, and with perfect 50-ohm source and load, then yes the frequency response will be a flat line until there's a knee and at that point there will be an increasing attenuation with frequency; the 3dB point is called the cut-off frequency.?
If the inductances are anything off perfect, then you can easily end up with a response which has a peak in it, and a few dB insertion loss at lower frequencies. If that peak of the response is not aligned with the operating frequency then you see low power. If the inductances are too low for the design, then increasing them to the design value can definitely increase the output power.?
What happens in QCX is even more complex because there is normally not a perfect impedance match between the PA and the LPF input. When you tweak inductance values the output power can be increased if the impedance match is improved.?
Practically speaking, when tuning up QCX LPFs I have often found that increasing the inductance of L2 improves everything. I know it is slightly counter-intuitive but this is the reality.?
Generally I think the correct approach is to see what happens to the output power when you squeeze the turns and when you spread the turns. If the power increases as you squeeze the turns, this means that increasing inductance is increasing the output power. If the maximum output power occurs when you bunched together the turns as much as you could, then the tuning range available from turns squeezing is not enough; so in that case try adding on another turn or two, then try again. Conversely if the maximum power occurs when all the turns are spread out evenly around 100% of the toroid core, then this means that the adjustment range is not enough in the other direction - and in that case try removing a turn or two, then try again.?
73 Hans G0UPL
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Re: John Palese, Jr, WB8JPH SK.
You're welcome, Pat, and I'm with you on that hope, though I'm nowhere near as accomplished as he is, and I am only recently finding my opportunities as a servant of the community. John wasn't a very active participant on the forum, and I didn't know if he had other friends who would have been more appropriate conveyors of the sad news, but he was a subscriber and a QCX user, and I had advised him on a new 80m plus and was building it for him, so we were acquaintances at the very least, and I didn't want it to go unannounced.
As we get older, life feels finite and precious, and I want us all in this hobby to wring out every last QSO we can. I'm sad John didn't get to use his QCX Plus; he'd have been impressed with it.
--
Julian, N4JO.
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Re: John Palese, Jr, WB8JPH SK.
Thanks for letting us know, Julian.? Very nice of you.? I hope my obituary is as nicely done as John's.?
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Re: Classic QCX C1 fully meshed
Well yes, if you pulled it down tight - as I do - then that will make it different to thread extra turns, for sure.
Glad you're up and running. Maybe the time energized "dried out" those caps or something. I'm not a chemical engineer, so I don't know how the chemistry works, but I do know that caps are very sensitive and variable things, and that will affect tuned circuits, which depend on them having stable value.
The classic is actually very easy to connect to a QLG1, because the 4-pin header is mapped identically on both devices, by design, and you just need a piece of ribbon terminated at both ends. I think the Bama case has a removable panel for access to the GPS header...
You just have to remember to not connect the GPS when you're not in WSPR or calibrating, as it will key the Tx.
--
Julian, N4JO.
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Re: Hints for successfully building the QDX
Thanks Mike. It's really a reciprocal process: electronics may be my trade, but I'm really new into amateur radio, so I'm learning a lot from you guys who have been it for longer, in some cases, than I've even been alive. I'm just paying it back :-)
I'll finish off my QDX tonight, maybe push out some more notes, and then get back to some other commitments I'm tardy on...
--
Julian, N4JO.
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Re: Classic QCX C1 fully meshed
Adding windings on T1. ?Cheaper? ?Yes. ?Easier? No. ?I pulled the T1 down tight when I installed it never thinking I would have to restring wire under it¡.. Glad I didn¡¯t have to.
Strange though¡.. I readjusted all the cap and pots today (the third time) and this time C1 peaked even higher and the plates of the rotor were 50% meshed, just like the photo. Go figure. ?The number in the upper right went from 07 to 09¡.. I retested it two more times. ?No extra caps this time. ?Two peaks at 50% each time. ?Also the dips of the three pots went down (as they should) as I kept balancing them again and again as the instructions state.
I have a QLG 1 I built two years ago so may try to learn how to connect it and use it for further adjustment of the crystal frequencies. It connected with the satellites through my narrow basement window soon after building. I was surprised but the GPS on my FT3D connects in the same manner¡.. can hardly see the sky.
Dave K8WPE David J. Wilcox¡¯s iPad
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On Nov 3, 2021, at 9:56 AM, Julian N4JO <n4jo@...> wrote:
?Think if it this way: adding turns of wire is cheaper, in the long run, and faster, and it can be done less destructively than replacing a cap. Given that sometimes one has to remove turns, then the skill, once learned, is easy to deploy either way. It isn't even harder, actually, even though it may seem that it is at first. The fact that you have two peaks means that you are able to tune the circuit, and that's all that matters.
Remember to put the battery voltage jumper in, if you're ever going to run it on batteries... then have fun with it, Dave :-)
--
Julian, N4JO.
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Re: Hints for successfully building the QDX
Julian,
Great writeup and thanks for everything you do for the members of this fine community of QRP enthusiasts!
This is by far my favorite Groups.io.....
Looking forward to my QDX build.
73
-Mike
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Re: John Palese, Jr, WB8JPH SK.
On Wednesday, November 3, 2021, 05:09:42 PM EDT, GIUSEPPE <iw8rsb@...> wrote:
Rest in peaces OM.
´³¾±³¾¡°²Ï3³§ On Nov 3, 2021, at 4:54 PM, Julian N4JO <n4jo@...> wrote:
? It falls upon me to announce that one of ours - John Palese, WB9JPH - is now Silent Key. He left us on Sunday October 17th.
I was doing some work for John - building an 80m Plus that he planned to use for CW traffic nets for EmCOMM, and "perhaps POTA for fun when I go from semi to fully retired a few years hence" - when he told me on the 6th October that he was hospitalized, and would I please "send via text as the wifi sucks" . The next thing I heard was from his XYL Angie on the 8th, saying that he was in the ICU with COVID. Having heard nothing for a while, I inquired the other day, and found the sad news. Angie gave me the OK to announce it here.
John was one of the best.
--
Julian, N4JO.
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Re: John Palese, Jr, WB8JPH SK.
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Rest in peaces OM.
´³¾±³¾¡°²Ï3³§ On Nov 3, 2021, at 4:54 PM, Julian N4JO <n4jo@...> wrote:
? It falls upon me to announce that one of ours - John Palese, WB9JPH - is now Silent Key. He left us on Sunday October 17th.
I was doing some work for John - building an 80m Plus that he planned to use for CW traffic nets for EmCOMM, and "perhaps POTA for fun when I go from semi to fully retired a few years hence" - when he told me on the 6th October that he was hospitalized, and would I please "send via text as the wifi sucks" . The next thing I heard was from his XYL Angie on the 8th, saying that he was in the ICU with COVID. Having heard nothing for a while, I inquired the other day, and found the sad news. Angie gave me the OK to announce it here.
John was one of the best.
--
Julian, N4JO.
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Re: John Palese, Jr, WB8JPH SK.
toggle quoted message
Show quoted text
On Nov 3, 2021, at 4:54 PM, Julian N4JO <n4jo@...> wrote:
? It falls upon me to announce that one of ours - John Palese, WB9JPH - is now Silent Key. He left us on Sunday October 17th.
I was doing some work for John - building an 80m Plus that he planned to use for CW traffic nets for EmCOMM, and "perhaps POTA for fun when I go from semi to fully retired a few years hence" - when he told me on the 6th October that he was hospitalized, and would I please "send via text as the wifi sucks" . The next thing I heard was from his XYL Angie on the 8th, saying that he was in the ICU with COVID. Having heard nothing for a while, I inquired the other day, and found the sad news. Angie gave me the OK to announce it here.
John was one of the best.
--
Julian, N4JO.
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John Palese, Jr, WB8JPH SK.
It falls upon me to announce that one of ours - John Palese, WB9JPH - is now Silent Key. He left us on Sunday October 17th.
I was doing some work for John - building an 80m Plus that he planned to use for CW traffic nets for EmCOMM, and "perhaps POTA for fun when I go from semi to fully retired a few years hence" - when he told me on the 6th October that he was hospitalized, and would I please "send via text as the wifi sucks" . The next thing I heard was from his XYL Angie on the 8th, saying that he was in the ICU with COVID. Having heard nothing for a while, I inquired the other day, and found the sad news. Angie gave me the OK to announce it here.
John was one of the best.
--
Julian, N4JO.
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Revised comment: When you change the circuit to move the frequency where the knee occurs higher, you also reduce the signal suppression at the harmonic frequencies. Need to be careful there. -- > I finally got it together...now I can't remember where I put it< VY 73, Wes
AE6ZM
Sierra Vista, AZ
?
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Re: Hints for successfully building the QDX
Yes thank you for taking the time to remind us of those things you stated.? I think one of the most important and overlooked suggestions is to read the manual start to finish first?before even heating up the soldering iron.? You'd be surprised the numerous ways that little bit of advice helps! Thanks for all you do for the group Julian!? 73, Steve KY4GX
Glory to God in the highest, and on earth peace, good will toward men. Luke 2:14
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QDX operational, after troubleshooting
I finished my QDX a couple days ago but was disappointed when attempting to power it on for the first time. All that's resolved now and I think it's going to be a very fun rig to use. My problem was a short between the windings of T1.
A brief video demo and further description here if you're interested:
--
John AE5X
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Re: Hints for successfully building the QDX
Jilian
Thank You excellent information especially the " TAKE YOUR TIME!" tip.
It is so much easier to find issues by checking each step once completed rather than try to guess where the problem might be.
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M0RON
Earl
Julian N4JO
David Wilcox K8WPE
Wes WB7BR
N3MNT