Elektor Fortissimo-100, Руководство по монтажу

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Elektor Fortissimo-100 Power Amplifier Kit
● 12
Figure 9. The SK53-100-SA heatsink in the kit.
2 – Introduction
Notice: It is strongly advised to closely read the entire Construction
Manual before starting the construction of the amplifier.
The design, especially the placement of the power transistors T17–T22
and the PCB, is aimed at easy replication. The mechanical work need-
ed should be possible with simple tools and basic skills like drilling 12
3-mm holes to mount the transistors and fasten the PCB in parallel
with the back of the heatsink. The fin spacing of the selected heatsink
(type SK53-100-SA from Fischer Elektronik) is sufficient for the heads
of the black 3-mm screws while also allowing room for some error.
The PCB is mounted onto the heatsink with six 10-mm long metal
male-female standoffs with 3-mm thread. The 6 transistors of the out-
put stage are electrically insulated with ceramic (Al
2
O
3
) pads, marked
by a lower thermal resistance than comparable types. During the final
stage of construction, apply some thermal grease on the back of the
transistors and on the sides of the pads placed against the heatsink.
Only a very thin layer is required! Take precautions not to get the ther-
mal grease on your fingers as most types are toxic.
The DC protection and relay circuit are placed on a second, smaller
PCB placed in parallel with the amplifier PCB. Six 30-mm long male-fe-
male metal standoffs ensure a solid construction. Standoffs K3 and K4