Ramsey Electronics QAMP20, Assembly And Instruction Manual

Page: 9 / 20

QAMP20 • 9
These last four parts (R8,9 and C11,12) form parasitic suppression networks
across each transistor to suppress any tendency for high frequency oscillation
in the power amplifier.
ˆ 32. Install C3, another .1 µf disc capacitor (marked .1 or 104). Both of
these capacitors bypass the center tap of the ferrite transformers to
ground. Bypass means to provide a low impedance path to ground.
ˆ 33. Install C1, 100 to 220 µf electrolytic capacitor. Be sure to observe
correct polarity.
ˆ 34. Install C4, 180
ρ
f disc capacitor (marked 180 or 181).
ˆ 35. Install C5, 330
ρ
f disc capacitor (marked 330 or 331).
ˆ 36. Install C6, another 330
ρ
f disc capacitor (marked 330 or 331).
ˆ 37. Install C7, another 180
ρ
f disc capacitor (marked 180 or 181).
ˆ 38. Install wire jumper, JMP1. Use a scrap piece of component lead wire.
ˆ
39. Locate the MOSFET power
transistors and prepare the leads for
insertion into the PC board. Bend
down the two outside leads about
1/8" from the transistor body and the
center lead about 3/16" from the
body.
ˆ 40. Mount the transistors and heatsinks to the PC board using the 4-40
screws and nuts. Solder all transistor leads. Note that the heatsinks
may look slightly different from the ones shown.
We're almost finished. All we need to do now is install a few remaining parts
that have to be handmade - for that "old-world craftsmanship" touch! We'll
prepare all those parts now for further assembly. We supplied plenty of
enameled wire for your kit but if you mess up, you can get a whole 50' spool of
it from Radio Shack (278-1341).
Transistor bend pix