Ramsey Electronics AM25, Сборка и инструкция по эксплуатации

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AM25
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We’ll now begin to construct the RF oscillator section of the AM25. Be sure
to mount the components as close as possible to the PC board to avoid
“radiating” any unwanted signals due to long lead lengths.
ˆ 4. Install L5, the slug tuned inductor. Solder all 7 tabs.
ˆ 5. Install L7, a 68 uH inductor, it looks like a resistor with color bands on
it, blue-gray-black.
ˆ 6. Install C35, .01 µF [marked .01 or 103 or 10 nF].
ˆ 7. Install H1, the 3 pin header strip. You will later place a jumper block
over a pair of pins depending upon which portion of the AM band you
wish to transmit on.
ˆ 8. Install R18, 4.7K ohm [yellow-violet-red].
ˆ 9. Install R19, 47K ohm [yellow-violet-orange].
ˆ 10. Install R28, 1K ohm [brown-black-red].
ˆ 11. Install D2, MVAM-108 varactor diode. This part looks like a transistor
with only two leads, pay attention to orienting the flat side correctly. A
varactor diode acts like a voltage variable capacitor. In this case we use
D2 to control the frequency of our oscillator and the PLL IC chip will
orchestrate it all to maintain frequency exactly as programmed.
ˆ 12. Install C13, .01 uf disc capacitor [marked .01 or 103 of 10 nf].
ˆ 13. Install C14, another .01 uf disc capacitor.
ˆ 14. Install jumper, JMP2. Simply use a small scrap of component lead
wire bent into a ‘U’ shape. Jumpers act as electronic bridges crossing
over circuit traces below.
ˆ 15. Install Q6, a 2N3904 NPN transistor. When installing Q6, observe
correct placement of the flat side. Press the transistor snugly into the PC
board so that only a minimum amount of wire lead is exposed above the
board. In soldering, do not be afraid of using enough heat to make a
good solid connection.
ˆ 16. Install Q4, another 2N3904 NPN transistor. These two transistors
comprise the carrier oscillator for your transmitter.
ˆ 17. Install R10, 1K ohm [brown-black-red].
ˆ 18. Install R4, 10K ohm [brown-black-orange].
ˆ 19. Install C28, 10 µF electrolytic capacitor. Electrolytic capacitors are
polarized with a (+) and a (-) lead and must be installed in the correct
orientation. Ordinarily, only the negative side is marked on the capacitor
body with a dark band and the (-) sign clearly shown, while PC boards
will usually show the (+) hole location. Use care to ensure proper
polarity.
ˆ 20. Install C18, .47 µF disc capacitor [marked .47 or 474].