15
Toroidal inductors L2-L8 are shown in the photos at right (Figure
8). Wind each of these toroids using the indicated cores, either T80-0
(brown, phenolic) or T94-2 (red, iron powder). All are wound using
#20
enamel wire. Use the wire length and number of turns shown.
Place each toroid on its photo and adjust the turns spacing so it is
similar to that shown. Re-check turns counts. (Recall that each pass
through
the core counts as one turn.)
Prepare the leads of these toroids as you did for L1.
i
The T94-2 cores (red) have one side which is painted a darker
color than the rest of the core. To improve the appearance of the
completed RF board, we suggest mounting all four of these cores with
the dark side down.
Install L2-L8, using cable ties as you did for L1. Match each
toroid to its reference designator carefully. Exchanging any of them
will make tune up erratic and may prevent the ATU from finding a
match.
Note:
Once in position, some of the toroids may be very close to each
other, and may even be touching. This will not affect performance.
Solder L2-L8.
On the bottom side of the board, check for continuity between
the pads of L2-L8. If you get a reading of over 1 ohm, remove the
toroid from the board and prepare the leads again.
__ L2: 10 T,
T80-0
__ L3: 16 T,
T80-0
__ L4: 23 T,
T80-0
13" (33 cm) 19" (48 cm) 26" (66 cm)
__ L5, 12 T,
T94-2
__ L6, 17 T,
T94-2
18" (46 cm) 24" (61 cm)
__ L7, 24 T,
T94-2
__ L8, 34 T,
T94-2
34" (86 cm) 46" (117 cm)
Figure 8
