Elecraft KX1 Manual - Manual (Page 51)

50
E
LECRAFT
Wind toroidal inductor L3 on one of the FT37-43 cores
as follows:
_ Cut a 14” (36 cm) length of red enameled wire.
_ “Sew” the long end of the wire through the hole in the core
for a total of 18 turns. Match the winding direction shown in
Figure 18. Count one “turn” each time the wire passes
through the center of the core. There are no “half” or
“quarter” turns when winding a toroid.
_ Spread the turns around the core so the finished result looks
like Figure 18.
_ Strip the insulation and tin the leads like you did earlier for
L1 and L2 (See page 41).
Wind toroidal transformer T1 on the remaining FT37-43 core
as follows:
_ Cut an 8” (20 cm) length of red enameled wire.
_ “Sew” the long end of the wire through the hole in the core
for a total of 8 turns. Match the winding direction shown in
Figure 15. Count one “turn” each time the wire passes
through the center of the core. There are no “half” or
“quarter” turns when winding a toroid.
_ Spread the turns around the core so the finished result looks
like Figure 16.
_ Cut a 6” (15 cm) length of green enameled wire.
_ Wind two turns in between the other winding exactly as
shown in Figure 19.
_ Strip the insulation and tin all four leads like you did for the
other inductors.
4
3
1
2
TIN ALL FOUR LEADS UP TO THE CORE.
Figure 19. Winding Transformer T1.
Install toroidal transformer T1 first as follows. It will be easier to
thread all four leads through the proper holes in the board if you install
it before L3.
_ Thread the leads through the holes in the board. Double
check to ensure you have the right leads in the right holes
(see Figure 19). The inductor stands up vertically over the
printed outline. You will notice that lead 4 cannot be pulled
tight without dislodging the turns. This is normal. Leave
enough slack in that lead to avoid disturbing the position of
the winding.
_ Solder all four leads.
_ Use your DMM to check for continuity between pins 1 and 2,
then between 3 and 4. The resistance must be less than 1 ohm
in both cases. If it is higher, you probably have a poorly
tinned toroid lead. It must be fixed before continuing.