Hello! I am working on soldering and setting up my QMX transceiver for the past few days. While working along the manual worked fine for most steps I've done already, I am completely confused by wiring the tapped inductor L401.

Researching the internet I've seen this step has been reworked completely due to 20m sensitivity issues, but I haven't found any unambioguous instructions on how to set L401 up. I've already done the 19 turns, then the tap with the 20th turn and than another 8 turns.

However, I am not sure which wire goes where and how to place the jumper wire as both manual and other web resources are ambiguous with regards to this.

Can someone please explain this to me in a simple and clear way and/or provide some photos of where the end of the wire and the jumper wire go?

Hi Haris,

The correct instructions are in the newest assembly manual?assembly_1_00i.pdf that is available on the QRP-Labs QMX page:


73
Evan
AC9TU

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Look at the pic at the top of page 30. The "X" means not connected.
The numbers indicate where the 19th and 28th turn are connected. The
28th turn is connected to two holes. I usually connect the 28th turn
to the last hole and run a short jumper back to complete the 28 turn
connections.

-mike/w1mt

The above picture from the most recent assembly manual is clear to me.? The first 19 turns go between the Start and the 3rd hole, skipping the second hole used in the original design.? ?The end of the 28 turns goes into the 4th hole with enough wire left over to act as a jumper to the last hole.? Since the holes first and last holes are smaller than the others, the end of the 28 turns best fits into the 4th hole that was sized for two wires.? It means that the wire at the end of the 28 turns is hidden in the picture under the toroid.? The jumper wire can be seen.

Here is the updated schematic that does show the toroid as a tapped inductor:?



Note that the jumper is shown as well.

73
Evan
AC9TU

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Hi folks! Thank you for your responses! I'm sorry, but I still don't feel sure about which turn/wire goes where. Be aware, I am somewhat of an electronics noob, as this is only my second practical electronics project (the first one being the Morserino-32 morse learning device, which was easier to understand and build).

My three crucial problems are:

• Looking at the photo, it looks as if the windings continue to the fifth and last hole, whereas the text says it should end at the fourth hole.
• I also have no clue how the jumper wire is meant to be laid. Just below the board, or with a tap at the fourth hole and then between board and toroid? Is it meant to be placed somehow loose, or does it go straight from fourth to fifth hole?
• Is the 19t tap meant to be cut through as well, or what should I do with it after soldering?

Maybe, a drawing would help as in explanations of how to tie a tie, where every step is signified by arrows. Maybe, a simple explanation could do, but from my perspective, this is too confusing.

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Harris,

Harris,
if you look at the main board pcb wiring on page 12 of the Assembly manual, it will be even more interesting.
Compare the wiring of the pcb with the drawing of Schematic 4:Receiver.
Surprise. This jumper circuit is technically a jumper between pin3 and pin4 of IC402.
You can also do this connection on the legs of the IC if you are skilled.
Since these legs are brought out to solder points, it is easier to make a connection there.
Why Hans solved it like that, let that be His secret.
--
Gyula HA3HZ

Thank you Cliff! Thank you Gyula! So if I got you right, the details don't matter ^{that much at least} and the crucial bits are:

• to have 28 turns with the tap at turn 19, and
• to short holes 4 and 5 or pins 3 and 4 of the IC.

So it's OK if I do the 28 turns up to hole 5 and then somehow short the holes or pins. Is this correct? Because if that's the case, then I'll do that.

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You got it. The idea of shorting the pins of the IC makes me uncomfortable even though it's theoretically valid. Over to you my friend.