Ramsey Electronics AM25, Assembly And Instruction Manual

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AM25
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Just what are these inductors? The inductors you just wound are called
broadband matching inductors. They act as impedance matching devices,
similar to a transformer. L4, for example has a 4:1 turns ratio and will
transform the low impedance output of Q3 up by 16 times. This is because
the square of the turns ratio is equal to the ratio of impedances.
Now let’s move over to the audio section.
ˆ 73. Install U1, LM358 opamp. Be sure all pins are through the PC board
and that the notched or marked end is positioned as shown.
ˆ 74. Install R26, 10K ohm, [brown-black-orange].
ˆ 75. Install R17, 2.2K ohm [red-red-red].
ˆ
76. Install R11, 100 ohm [brown-black-brown].
ˆ 77. Install C27, .01 µF disc capacitor [marked .01 or 103 or 10nF].
ˆ 78. Install C23, another .01 µF disc capacitor.
ˆ 79. Install C15, .1 µF disc capacitor [marked .1 or 104].
ˆ 80. Install R12, 470 ohm [yellow-violet-brown].
ˆ 81. Install R8, 100K ohm [brown-black-yellow].
ˆ 82. Install R5, 100 ohm [brown-black-brown].
ˆ 83. Install JMP3 using a scrap component lead wire.
ˆ 84. Install Q8, 2N3904 transistor, observe placement of the flat side.
ˆ
85. Install C17, .01 µF disc capacitor [marked .01 or 103 or 10nF].
ˆ 86. Install C22, .1 µF disc capacitor [marked .1 or 104].
ˆ 87. Install C34, the large 470 µF electrolytic capacitor. Be especially
careful to observe correct polarity when installing this part. If installed
with polarity reversed, it can explode.
ˆ 88. Install R21, 10K ohm [brown-black-orange].
ˆ 89. Install R23, one of the small yellow trimmer pots. Be sure it is seated
fully on the board before soldering.
ˆ 90. Install R14, 10K ohm [brown-black-orange].
ˆ 91. Install R27, another 10K ohm resistor [brown-black-orange].
ˆ 92. Install C29, 10 µF electrolytic capacitor, observe correct polarity.
ˆ 93. Install R31, the other yellow trimmer pot.
ˆ 94. Install C21, another 10 µF electrolytic capacitor, watch polarity.
ˆ 95 Install R13, 1K ohm [brown-black-red].
ˆ 96. Install R22, 10K ohm [brown-black-orange].
ˆ 97. Install R29, 1K ohm [brown-black-red].
The following transistors are capable of higher power than the little guys
you’ve been installing. Because of their higher power abilities, they will