Micro Bf treatment on
ICOM IC-U200T

Arnaud Cabaret, F6gnj
12/02/98

Diagram
Traditional: amplification, limitation, filtering. The positive food is ensured by the line " T8 " (8 volts present has the emission). The joined photographs make it possible to locate the connector J510 or one can take the food 8 volts and the mass. Attention, the drawing of Ci is has scale 2.

Assembly
The components are them also traditional and should be able to be in the funds of drawers. (No CMS...) To note cutting in bevel of Ci to let pass the magnet of the HP.

Installation
The photographs speak about them same... Attention nevertheless with the drilling of the chart " hand board ", to make sure that the zones of mass are in glance and that there is enough place to pass the head of the screw of 2,5 Misters a spacer of 4,5 mm positions Ci has the good height so that it avoids quartz and serves of that Ci to avoid moving!!!

Connected
For the food, to refer to the photographs to locate the useful connector J510 and pins. To weld 2 wire under the principal circuit and to connect them have the chart préampli (J4). For the inputs/outputs, Ci was conceived to position just with the top of the useful points!!!. To locate the falling " strap welding " has the balance of J1 of the chart préampli (short circuit the entry / left B.F.). To remove the welding and by same the cable finished by a connector female 3 points (entered BF/masse/sortie B.F.) at the same place but under the circuit
the main thing. To weld two " tails of resistances " onto J1 with dimensions welding and to cut them has 4,5 mm of the circuit, to go up and to screw the chart préampli then using an iron has fine breakdown, to weld wire in glances onto the points of the old strap between the two circuits.
For the awkward ones, to weld flexible wire to join together the two circuits, attention has the length... or quite simply to use the cable armours origin welded under the circuit by removing the connector.

Adjustments

- RA1 1/2 of the supply voltage. To control if required has the oscilloscope the symmetry of a sinusoid injected has the entry.
- RA2 Profit of the preamplifier (micro sensitivity).
- Ra3 Excursion. If the B.F. of attack is too important, the stage préampli saturates and limit by the supply voltage.
(Not always very beautiful, but effective...)

Valeur Leaves
- -
C1 10mF
C2 0.1mF 1mF polarizes so untraceable
C3 4,7mF
C4 1mF
C5 4,7mF
C6 10n
C7 2,2n
C10 10n
C11 1n
C12 100p Not of 25 Khz (150p for the step of 12,5 Khz)
C13 2,2mF
J1 IN/OUT By strap on chart " hand board " or shielded cable of origin
J4 ALIM On J510 of " hand board "
R1 1,2k
R2 470k
R3 6,8k
R4 270k
R5 39k
R6 120k
R7 100k
R8 39k
R9 100
R13 4,7k
RA1 10k adjustable Potentiometer standard T7YA
RA2 220k adjustable Potentiometer standard T7YA
RA3 4,7k adjustable Potentiometer standard T7YA
U3 LM324N