Small Wonder Labs
PSK-20 Transceiver Kit 03/09/10
2000
20
Group 9 Assembly:
Group 9 assembly installs the transmitter final
amplifier and lowpass filter.
Snip a 12" (30 cm) length of wire from the
heavy wire bundle supplied with the kit. Nick
the insulation jacket slightly to expose one or
more individual wires- pull these out of the
jacket (discard the jacket).
Save the remaining length for later use.
Using one of the 12" wire lengths , wind 13
turns on one of the 1/2" (1.2 cm) diameter
yellow
toroids. After passing the wire through
the center hole each time, pull it snug against
the toroid as you proceed. Make sure that
each turn lays flat on the core- 'crossed' or
scramble-wound turns must be avoided.
Doublecheck the turns count, adjust the
spacing between turns for a uniform
appearance.
Trim the excess wire length to 3/8" (1cm)
and strip the insulation off the leads using a
wirestripper or hobby knife. Install at L11.
Using a second 12" wire length and yellow
toroid , repeat the above sequence and install
this 13-turn toroid at L13 (nearest to board
corner).
Using a third 12" wire length and the last
yellow toroid, wind 14 turns and install at L12
(
mounts at right angles to the two toroids
already installed
).
Remove the individual wires from the
remaining length of wire bundle.
Select any 2 of the 4 wires and pass both
through the hole in the toroid.
Wrap this wire-pair snugly around the toroid
for one complete turn. It should look like
this:
Proceed to thread the wire pair through the
hole again and draw it snug . Repeat this
threading operation twice more (a total of 4
wire-pair turns through the hole in all).
Caution:
The wires must not cross over each other
as they are laid down on the core (i.e.,
there are no 'twists' built into the wire. If
(color 1) is on the leading edge in the
direction you're winding, it must continue
on the leading edge for all 4 turns.
'Clockwise' and 'counterclockwise' winding
senses are non-critical- either one is fine.
Here's what the result looks like:
Note the way the color-pairs are arranged as
they proceed around the core.
As you look through the toroid hole (as
shown above, confirm that the 2 (first color)
leads protruding are on the left and the 2
(other color) are on the right.
Cut the protruding leads to a length of 1/2",
strip these with the wirestripping tool and
install at
T2
. Doublecheck the insulation
colors before soldering this component
down.-
Install C40 and C43 (150 pF monolithic caps ,
'151J').
Install C41 and C42 (330 pF monolithic caps ,
'331J').
