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QMX kit mid band - Missing a few cm of 0.33mm and 0.60mm wire #kit #qmx

 

After cutting all the wires to spec (some even shorter than spec) to build all the toroids, I realised that I¡¯m missing about 2.5cm of 0.60mm wire and about 30cm of 0.33m wire to build T507.
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Am I the only one experiencing this?
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73 de F4JAW
Pedro
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I have not. I¡¯ve always been careful about cutting them to measurements pretty exactly. With all the kits I end up with more than needed on the toroid but not by much, and a little left over after they are all done. Again not much. I¡¯ve always been amazed how close it comes out.?
 

This happened to me on my first QDX kit. As W0WLY noted, I always had more than I needed left on the toroid when I used the exact amount stated in the instructions, and ended up not having enough for the last toroid. Fortunately, I had an old transformer I could scavange some wire from to complete the last toroid.
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On my second QDX, I used something like 4 or 5 cm less wire per toroid than called for and ended up having enough wire for everything. When I posted to the group about this, several others said they had the same problem (several also said they did not have this problem).
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I haven't built my midband QMX, yet, but have always wondered if I needed to do the same with it, i.e. use a few cm less wire per toroid than the instructions call for. Some say they like to have extra wire for the toroid because it makes it easier to wind. I don't have a problem using less wire (and possibly having less risk of running out).
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So I guess my question would be, on the QMX kit, can you cut each toroid wire, say, 4 cm shorter than called for in the instructions and still have it be long enough to wind each toroid completely (thus, ensuring you have enough wire for everything)?
 

As a follow up, here's the QDX wire post I mentioned in my earlier comment above:
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/g/QRPLabs/message/87536
 

You could always use to get another estimate of the length required.

73
Roger
8P6RX

Get
On 16 Oct 2024, at 05:20, DD5ET <dd5et.scott@...> wrote:

This happened to me on my first QDX kit. As W0WLY noted, I always had more than I needed left on the toroid when I used the exact amount stated in the instructions, and ended up not having enough for the last toroid. Fortunately, I had an old transformer I could scavange some wire from to complete the last toroid.
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On my second QDX, I used something like 4 or 5 cm less wire per toroid than called for and ended up having enough wire for everything. When I posted to the group about this, several others said they had the same problem (several also said they did not have this problem).
?
I haven't built my midband QMX, yet, but have always wondered if I needed to do the same with it, i.e. use a few cm less wire per toroid than the instructions call for. Some say they like to have extra wire for the toroid because it makes it easier to wind. I don't have a problem using less wire (and possibly having less risk of running out).
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So I guess my question would be, on the QMX kit, can you cut each toroid wire, say, 4 cm shorter than called for in the instructions and still have it be long enough to wind each toroid completely (thus, ensuring you have enough wire for everything)?

 

On my mid band kit I'd say in theory it might be possible to optimise in a way you have enough wire for everything. In practice when you deviate from the instructions in the manual you're in uncharted territory and it will take only one wire cut too short to make it impossible for the rest to be enough.
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In my case I followed all the lengths from the manual (even when I thought it might be too long) and only managed to optimise a bit on the small toroids. In the end the wire is still not enough.
This is very annoying because now I'll have to find some more online (while there are just a few cm missing) with added costs, shipping costs and delays...
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It's a frustrating kit building experience.
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When I find time to build my QMX+ kit, i'll save for last
the 160m low-pass transmit filter toroids.
Then if I mess up something critical like T501,
I'll have enough wire for a do-over.
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Jerry, KE7ER?
 

On Wed, Oct 16, 2024 at 09:42 AM, Roger Hill wrote:
You could always use??to get another estimate of the length required.
Sure, you could for all 10 or so toroids, I suppose, but I would think that at least one of the hundreds of builders of QMX kits so far would have paid enough attention during the build to be able to say whether or not you could make each wire, say, 4 cm (or 3 cm or whatever) shorter and still be long enough to easily wind each toroid ... and save the rest of us some time and, possibly, heartache.
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It is easy to do, and gives you a cross check.

By the way, I have built at least 5 of Hans's kits, and never run short of wire for toroids.

73
Roger
8P6RX

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On 16 Oct 2024, at 10:40, DD5ET <dd5et.scott@...> wrote:

On Wed, Oct 16, 2024 at 09:42 AM, Roger Hill wrote:
You could always use to get another estimate of the length required.
Sure, you could for all 10 or so toroids, I suppose, but I would think that at least one of the hundreds of builders of QMX kits so far would have paid enough attention during the build to be able to say whether or not you could make each wire, say, 4 cm (or 3 cm or whatever) shorter and still be long enough to easily wind each toroid.
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As some of my college professors used to say, "it is intuitively obvious to the casual observer" after building my first QDX that the wires could be cut some small amount shorter and still be long enough. On my second QDX build, that turned out to be the case. Perhaps someone who has built a QMX has made the same observation and can say whether or not that's doable ... and save the rest of us some time and, possibly, heartache.

Robert AD6XJ
 

I only left 2-5 cm tails on most of my toroids and I used 30AWG for the 38t coil L506 which left me with 150cm of wire remaining from my QMX+ kit. I wish I could tell you how-- but I was doing it while watching TV and didn't keep notes. But I think I wound ten turns, marked the wire, took it off the toroid and measured the length, that length divided by ten provided the wire length per turn then add 5cm for the two leads. All of the pink, yellow, and blue toroids have similar cross section so all I had to do was rinse-lather-repeat-- eighteen times! for "Twisted Sister" T501 I followed documentation to the letter. For the trifilar T401 I followed the documentation mostly, sort of. Other folks wiser than I have informed me that eight turns per inch is a good twist rate and I used a pair of hand held drill chucks (if you ask, I'll tell you why I have twenty-odd drill chucks around the shop) to hold the ends of the three 20cm (8 inch) strands and twisted 64 times (8tpi times 8 inches)-- a bit tedious, but I was in my recliner watching TV while doing the coil winding. BTW an egg flat makes a good lap sized sorting tray.
 

On Wed, Oct 16, 2024 at 07:50 AM, DD5ET wrote:
I would think that at least one of the hundreds of builders of QMX kits so far would have paid enough attention during the build to be able to say whether or not you could make each wire, say, 4 cm (or 3 cm or whatever) shorter and still be long enough to easily wind each toroid ... and save the rest of us some time and, possibly, heartache.
I can say this.? For my QMX, I noticed after winding the first toroid that the length of the wire tails was more than necessary by a few cm, even allowing an extra 6-8 cm on the far end to make winding easy.? So for the remainder of the toroids I cut the wire a few cm shorter than the instructions called for, and ended up with a long piece of the smaller wire, and just a few cm left over of the larger wire.? Note that in winding each toroid, I only allowed about 2-3cm for the starting tail - enough to hold on to, and ample for installation, but not lots of extra, and then I wound the turns very tightly on the toroid.? ?How much shorter did I cut each wire? I can't say exactly,? but I measured the extra length I had from the first toroid, and left about half of that off on the second, to give me confidence, then chose a length to exclude from the rest.
However, after saying this, I will also say that the amount I had left over at the end gave me to believe that there would have been enough wire to use the instructed lengths.? I'm confident that Hans is providing enough wire in the kits.
 

I have always had more wire than I needed for QRP Labs kits - and I have built 12 of them. However, one thing I do is NOT to cut the wire before I wind each toroid. I don't mind using the entire length when I wind the toroid. That way I never use more than about 12 cm extra wire for each toroid. And I keep every bit of extra wire just in case the next kit is short.?
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73, Dan? NM3A
 

So you¡¯re telling me that you ignore the instructions regarding the wire lengths to cut so you can have enough wire in the end? I was assuming that carefully following the instructions from the manual would guarantee a successful outcome. In my case I ended with rather long legs on each toroid and not enough wire to wound T507. Frustrating kit building experience.
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I¡¯m also thinking that maybe this is due to the special case of the mid band kit having two L401 toroids instead of one and the team not counting on that extra wire. But this doesn¡¯t explain the few cm lacking on the 0.60mm wire¡­

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