QRP PROJECT Blue Cool Radio, Manual

Page: 12 / 45

Rev: November 20 2006
12
To prepare the Bobin take the Body, give
a drop of superglue between the snap in
part middle of the socket and snap the
body to the holder. Give the glue a
chance to dry before you go on with the
coil. In the mean you may install some
further parts of section 4.
[ ] DR5 100uH SMCC B-5
[ ] C20 47nF (473) B-5
[ ] C22 47nF (473) B-5
[ ] R16 12K upright B-5
[ ] R17 8,2K A/B-4/5
[ ] D10 1N4148 A/B-4
[ ] C92 22pF (22j) A/B-4
[ ] C27 6,8nF (682) B-4
[ ] P5 50K PT6 Trimmpot B-4/5
[ ] T5 BF199 B-5
So, the glue should be dry, let´s start with
the coil.
Look at the Coil from the upper side and
hold it above the left picture. 2 Pins at
the left side, 3 pins at the right side.
At both the upper and lower side of the
socket, you will see a notch. This notch is
the way the wire has to go if it crosses
from the Socket Pins to the Bobin Body.
Lets´s start:
Sling one end of the wire as it is (no
solder) 3 times around PIN 1. This 3
turns around the pins schould be directly
below the socket, about 1-2cm Look at the picture left, it shows the Bobin
socket from the bottom side to make clear, how the wire is fastened to the
pin. The Pins are very rough so the wire will hold in place.
Now up through the notch to the Bobin Body and clockwise 18 turns
around the body. You will end with turn number 18 just behind PIN 2, go
down through the notch and wind 3 turns around PIn 2 the same way you
did it at PIN 1. Cut the wire leaving a little tail of abt 1-2 cm again.
Thats all, the Resonate winding is finshed. L4 needs a coupling winding This
consists of 2 turns. Start at PIN 3 again with 3 turns around the pin very
next to the body, go up throuh the gap and wind clockwise 2 times around
the body. You will end at Pin 4. Go down through the notch, 3 times
around PIN 4 and cut the wire you dont need for this coil 1-2 cm behind
the pin. This coil is ready, except it has to be soldered now. The easiest way
to do is to hold it with the PINs upside in a vice to have both hands free.
Clean the tip of your solder iron carefully. Now touch the 3 turns around a
Pin with the solder tip and at the same time with thin solder. Temperature
of the solder iron should be between 350 and 400 dreges Celsius. Wait 1-3
second until the solder flows and remove the iron. The laquer on the wire
normaly momentary is cracked and she copper is tinned to the Pin. After
soldering the 4 pins cut of the wire tails and check your work with an
ohmmeter. Result must be: about zero ohm betwen 1/2 and 3/4.
If this is ok, you can prepare the rest of the coil. Take the blue plastic
holder and the ferrite cap and screw the cap into the blue plastic holder. Do
the first turns without a tool, use your finger. Try to do it without too
much power. The ferrite and the plastic
must be in one axis. Try two turns
forward, one backwart several times.
Doing it this way, you will get a nice
threat into to plastik making later
adjustment of the coil easier. Now place
the coil on its place with the 5 Pins
through the holes in the PCB. Adjust the
coil to stand exact upright and solder the
Pins, do not use to much solder. Carefully
check that no extra solder is to see at
the upper side at the pins which could
cause a short to the shield.
2
1
3
4
Bobin
Body
3 Turns just below the socket