QRP PROJECT Blue Cool Radio, Руководство пользователя

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Rev: November 20 2006
22
Schraube
Mutter
Isolierhut
TO220 Gehäuse
Silikongummi Unterlegscheibe grau
Platine Platine
M3
Use an RF probe to measure the RF at the collector of the driver transistor,
that is the housing of the transistor. The power can be regulated by the
power potentiometer.
If this is ok, you can do the last step, instlling the PA
Group 8 PA
There are only two part in this section to be installed, but this should be
done very carefully.
Start with the PA Transistor. It must seated absolutely flat on the PCB
Ground plane. Because BCR is working in C-Mode with a very high efficiency
it does not produce too much heat, but it is better to keep it as cool as
possible. The metall plate of the PA Transistor must be insulatet from the
groundplane, so we use a modern silicone insulator.
DO NOT USE any type
of grease as it was done in older times. We have found the grease in
combination with RF Power Transistors often cause self oscillating in the
200 MHz range.
Bend the legs of the transistor with the help of a small screwdriver round
downwards as shpwn in the picture. Place it together with the insulator on
the board and adjust the legs until the transistor is lying really flat on the
board. Now screw it to the bord. If this has been done, solder the legs from
the bottom side.
[ ] T15 2 Silicone insulator. F/G-3/4
Last thing to install: the output transformer. Again it is a pignose, only a
little bigger than the other one. This time it is an step up transformer. Both
windings are made from 0.5mm enameled wire.
Because it is not possible to identify primary and secondary by the
thickness of the wire, you should mark the primary side of the pignose. Very
usefull to do this is nail laquer.
The primary gets 2 turns (Solder point 1 and 2) the secondary gets 4 turns
(solderpoints 3 and 4)
Build the transformer, tin the wires and install it at its place.
[ ] Tr2 BN43-202 pignose G/H-3/4
primary 2 turns 0,5mm enameled wire
secondary 4 turns 0,5mm enameled wire
That´s all.
before you start testing the PA, again check your work. Dont put your BCR
in the enclosure now but do the last test without enclosure.
Connect a dummy load to your BCR
connect a power supply which can handle 2 A
If you have worked with a low current fuse inside the BCR, change it against
a 1,25A or 2A fuse.
connect a morse key
Switch the BCR to on.
Choose Keyer off in the menue
Hit the morse key
Measure the power. It must be adjustable with the power potentiometer
between 0 Watt and 5 Watt. On the lower bands you will get some more