Ramsey Electronics HR40 Manual de Instruções descarregar pdf (Página 13)

FHT-1 • 13

microcontroller, causing the crystal oscillator's frequency to change - in

exact step with your CW ID. Voila, FM or Frequency Modulation!

 44. Install C33, .01 uF disc (marked .01 or 103 or 10nF).

 45. Install R8, 270 ohm (red-violet-brown). Make sure you stand this part

up.

 46. Install trimmer capacitor, C43 (black body with orange top). This

trimmer is used for setting the FHT-1 exactly on frequency.

 47. Install C27, 15 pf disc capacitor (marked 15 or 15K).

 48. Install R5, 47K ohm (yellow-violet-orange).

 49. Install C30, 470 pf disc capacitor (marked 470 or 471).

 50. Install C24, 100 pf disc capacitor (marked 100 or 101).

 51. Install C32, .001 disc capacitor (marked .001 or 102).

 52. Identify Q1, a 2N3904 NPN transistor (marked 2N3904). Install Q1,

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.

 53. Install D3, zener diode (gray body with black band). A zener diode

functions as a voltage regulator since it has the property of holding the

voltage across it constant. In this case we wish to hold the voltage to the

crystal oscillator steady to keep us on frequency, even with a poorly

regulated power supply.

 54. Identify Q2, another 2N3904 NPN transistor (marked 2N3904).

Install Q2, observe correct placement of the flat side.

 55. Install C9, .1 uf disc capacitor (marked .1 or 104).

 56. Install C8, .001 uf disc capacitor (marked .001 or 1000 or 102).

 57. Install R7, 470 ohm (yellow-violet-brown).

 58. Install C23, .001 uf disc capacitor (marked .001 or 1000 or 102).

The oscillator and the first buffer stage of the transmitter is finished. Take a

break and look over component placement and soldering. Are all the

components (except the stand up resistors) flat to the board? If not, be sure

to “walk” them to the PC board by heating one solder pad at a time and

pushing that end of the component flat to the board while the solder is still

molten, kind of a strike while the iron is hot technique. If this technique is

used, be especially careful not to lift the printed circuit pads or traces away

from the board material.

 59. Install C44, .001 uF disc cap (marked .001 or 102).

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Ramsey Electronics HR40 Manual de Instruções Página 13