13
Place relays at locations K1-K18. The relays can only be installed
one way.
Do not solder the relays yet, and do not clip or bend
the relay leads.
Using a thin hardcover book to hold the relays in place, flip the
PC board and book over together.
Solder just two diagonally opposite corner pins on each relay.
Turn the board back over. If any relay is not flat against the
board, re-heat its corner pins one a time while pressing down on the
relay.
Once all relays are properly seated, solder the remaining pins. Do
not trim relay leads, which can cause mechanical stress, reducing the
life of the relay.
Inductor Winding and Installation
A number of toroidal inductors are used on the RF board.
1
The first
four inductors to be wound use type T80-0 cores.
80
specifies the
outside diameter in hundredths of an inch, in this case 0.80 inches
(20.3 mm). The
-0
suffix refers to the core type, in this case
phenolic
. In addition, four T94-2 cores are used (0.94", 24 mm). The
-2
refers to an
iron powder
core type.
There are also two ferrite toroidal cores used, one of type FT37-43
and one of type FT50-43. In this part number,
FT
identifies the core
as ferrite, and
-43
identifies the type of ferrite. The number in the
middle again specifies the outside diameter.
37
, the smaller size, is
0.37" (9.5mm).
50
, the larger size, is 0.50" (12.7mm). Both ferrite
cores are dark gray in color and can only be differentiated based on
their size.
Three types of enamel wire are supplied with the kit: #20 red, #26 red,
and #26 green. #20 wire is much larger in diameter than #26. Be sure
to use only the type called for in the instructions; do not substitute
other wire types. Cut wires to the specified lengths to avoid running
out of wire.
1
Pre-wound toroids are available from an Elecraft-approved source; see page 3.
Sort the large toroidal cores into two groups: brown (T80-0, .80"
[20 mm]) and red (T94-2, 0.94" [24 mm]).
i
#20 enamel wire is quite stiff. After winding it tightly
onto the core, you may find that there's a small gap between
the wire and the core's flat surfaces. This will not affect
performance. If you try to wind the this wire so that it "hugs"
the core all the away around, you may have to pull the wire too
hard, resulting in hand fatigue.
A T80-0 core (brown phenolic) will be used for L1. Cut 9 inches
(23 cm) of
#20 red
enamel wire. To wind L1, "sew" the long end of
the wire through the core.
Each pass
through the core
counts as one
turn.
Exactly 6 turns are needed, as shown in Figure 6. The enamel
insulation will be removed in a later step.
Figure 6
Place L1 on top of its photo (Figure 6). Adjust the turns until the
spacing is similar to that shown. If the spacing cannot be matched, it
may be because you have one turn too few or too many.
Trim L1's leads to about 3/4" [19 mm] long as shown.
