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Re: QMX+ RF PWR Question
Bill,
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in the QMX+ all the bands (except 160m and 6m) share LPF in pairs (80/60, 40/30) or triples (20/17/15 and 12/11/10). This means that tweaking an LPF to get half a Watt more on a middle band will disturb the output PWR on the other bands that share the same LPF.
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I personally playeth the "squeeze-me-and-stretch-me" game for about 10 minutes, saw that it was not worth the effort, and started calling CQ straight away HI. Got an immediate 599 and 20min rag-chew on 20m, which is the band I had tried to squeeze and stretch the longest,? and which is still the one with the lowest PWR of all (2.7-2.8W).
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Most operators fall off their chair when you tell them you are running 3W (I don't even bother saying 2.8W on air...), and if condx are good they rush off to confirm "UR RST IS 599 REAL 599 REAL" in the following QTC? :)
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Enjoy using your QMX+. It's a fantastic little rig ;)
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72/73 de Enzo M0KTZ |
Re: 50w PA 80m version overheats transformers?
Hi Jonas, ? “T1 becomes hot” makes me wonder whether you could be experiencing oscillation caused by RF feedback through bias or QSK circuitry. Does your power meter move in accordance with your keying? ? I recommend you change supply voltage between, say, 12V and 20V at small increment, and see whether the problem exists to some extent (not very hot, but still warm) at lower voltages, or appears suddenly above a certain voltage (such as 18V). If the latter, I would suspect oscillation is likely. The culpit would be degradation of RFCs L9 and/or L10. ? 73, Aki, JO4MTH |
Re: Tools
On Sun, Oct 6, 2024, at 19:36, Donald S Brant Jr wrote:
You may have just saved what I jokingly call my sanity! One of the things I was not looking forward to when I take up my second attempt at building the QMX+ was the enamel stripping shenanigans! Michael WD0OM |
Re: Tools
On Sun, Oct 6, 2024 at 11:32 AM, Greg McCain wrote:
* Quite a process!
Hans recommends thermal stripping as well, BUT frequently if not daily on this forum there is a tale of woe by one kit builder or another, which after more or less struggle, turns out to be caused by inadequate enamel removal.?
Maybe more experience would give better results, but the fact is that there are a lot of problems with getting it right.
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I use and recommend to use this Knipex tool and avoid the hassle: ?
They sell additional sizes of blades but I have had great success with the default one.??
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I sure miss the old, hazardous Strip-X chemical enamel (and flesh!) stripper.? ?Nasty phenol-smelling stuff but the enamel came off clean and the wire was shiny and un-nicked, ready for tinning.? ?
73, Don N2VGU |
Re: 50w PA 80m version overheats transformers?
There is little power going through T1.? Any heating its from the heatsink.
Or something is radically wrong.
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I've not seen any great heating of the transformers.
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I'd suspect the bias is set above the suggested value.
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--
Allison ------------------ Post online only,? direct email will go to a bit bucket. |
#QMX PTT for SSB with built-in mic?
#qmx
I'm excited with Han's update for SSB, imagining me using my handheld QMX like an HF walkie-talkie.
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From the operating manual, I see the paddle port wiring for the external microphone and the PTT switch, but no explanation about the built-in mic.
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So how will we use the built-in mic for SSB? Would we still need a PTT switch connected to the paddle port, if not VOX used? Or, can one of the four push buttons be used for PTT in the SSB mode, by some firmware update?
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73,
Yoon KM6KJI |
Why?
#qmx
Why is it that I am 2 for 2 when it comes to having ugly diodes across one of the power supply boards? After the first one, I should have known to treat the boards with a lot of respect (which I think I actually did).?
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OK, I have to admit that debugging the problem was kind of fun.?
If I ever build another one, I may just remove all these SMD diodes and replace them with “ugly” diodes before I even start the assembly process ;) -- Karl Heinz - K5KHK |
That brings tears to my eyes - I really bonded with the prototype that I touched back in ‘19. And then of course the bigger problem: What will I do with the QSX PA that sits here, ready for the rest of the system? ?
;) --
Karl Heinz - K5KHK |
Re: Ultralight vertical offer
The article shows some of the prototypes (Figure 7) I made on the way to the lightest weight version. They work fine but are just taking up shop space so I'll gladly give them away for the cost of postage. (Only the loading coil, no telescoping whip or choke but I might throw in a radial set.)? |
Re: Tools
Phil is right about the Pan Vise.? I used one years ago when working as a bench tech.
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But,? here's one from Amazon that I've used for several years for my hobby level fun that won't break the bank.? Velleman VTHH6-VP Circuit Board Clamping Kit, 11.81" x 6.5" x 4.92" Size On Sunday, October 6, 2024 at 05:45:53 PM EDT, PHILIP GRAITCER via groups.io <pgraitc@...> wrote:
One essential tool for all kit building is a device to hold your the object your are working on. There are lots of “third hands” on Amazon, but I prefer a PanVise. It is fully adjustable and steady as a rock. I use it to hold PC boards and model ship hulls. Phil, K3UT |
Re: Tools
I actually don't have the Hakko.
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I have a 20 year cutter that I got back when there were real electronics shops around.? I just searched on Amazon for "component micro cutters" and picked the Hakko picture to attach. I know that Hakko tools are pretty good. It was listed as a top pick. And its only $5.47.? They are not really for cutting through thick stuff, just clipping component leads or wire up to 1.3mm. The very skinny top allows you to get at least in closely packed circuits.? Greg ads
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Re: 50w PA 80m version overheats transformers?
Jonas
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note all 3 are getting hot, while only the last one experiences full output power. Note they are attached to the heat sink, so they become part of heat sink. If your DC bias current is as described in manual, things should be okay.?
once I discovered the hot regulator in my ubitx, thinking it was faulty. It’s normal. Always good to think.?
Curt wb8yyy?
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