ZachTek WSPR TX Mini Build Instruction Download Page 19

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Document version 1.1 Page | 19

One Turn

Two turns

If you get lost in the count then you can recount the number of turns by using the following rule:

look at the

core from above and count the number of wires that cross the top side of the core

, se picture for an example of

a 17-turn toroid

END OF DOCUMENT

Summary of Contents for WSPR TX Mini

Page 7: ...s are fixed and soldered to one side let s go ahead and solder the other pad as well You might want to turn the board around to get the best working angle Be quick when heating and applying solder so you avoid melting the opposite side or else the cap might come lose and move about on the board ...

Page 9: ... if you are unfamiliar how to wind toroidal inductors see the winding guide in the appendix After you have wound inductor L2 it s wires are probably a bit long like in the picture Cut the wires down to length leaving about 12mm half an inch Now we need to get the enamel off the ends so they can be soldered To do that first burn the ends with a flame ...

Page 10: ...e soldering iron and some solder If you have done a good job getting the enamel off it should take solder easily if not scrape some more with the knife and pre tin again It is important to get the enamel off or else the coil might not make god contact when soldered in to the board and as a result you might not get a signal trough your filter ...

Page 11: ... top of the board and solder it on the underside so you have to be able to turn the board up side down without the toroid falling out You can hold the toroid in place in some way or you can bend the leads on the underside use whatever works for you Solder the two leads ...

Page 12: ...ter OK well done so far looking good Now continue winding the other two L1 and L3 they have the same number of turns again look in the low pass filter table to find out how many turns to wind Use the same procedure that you used for L2 to wind trim leads tin leads and finally solder in to the board ...

Page 13: ...Document version 1 1 Page 13 The result will look like this Last step is to verify that everything works using the built in signal generator and an oscilloscope ...

Page 14: ...fying the output Connect the board to a PC and start the configuration program Set it in Signal generator mode and pick the correct frequency in the screenshot below I am testing a 30m filter so I have set the signal generator to 10MHz ...

Page 15: ... on the oscilloscope as the picture below shows Check the oscilloscope you should see a nice sinus curve with about 3 3V Peak to peak value at the frequency you have set There is some small amount of loss in the filter so the peak voltage will probably be slightly less in the picture below it is 3 24V that is a very good result ...

Page 16: ...gher than that the LP filter frequency eg don t set it to 14MHz if you are testing a 10MHz filter If no signal can be seen then double check your solder joints If everything checks out you are done It is time to connect your WSPR transmitter to an antenna and start watching for spots Oh yes nearly forgot You can open that beer now Sweet ...

Page 17: ...Document version 1 1 Page 17 Appendix SMD low pass filter table ...

Page 19: ... you get lost in the count then you can recount the number of turns by using the following rule look at the core from above and count the number of wires that cross the top side of the core se picture for an example of a 17 turn toroid END OF DOCUMENT ...