Ramsey Electronics COMPUTEMP CT255 Manuel d'instructions télécharger pdf (Page 12)

FR6 • 12

the PC board. In this case, the control lugs are wired to the PC board using

your own insulated hookup wire, kept as short as possible for neat installation.

All "directions" on the PC board (ie: right, left, above, below and so forth)

assume orientation of your board as shown in the parts layout diagram.

Therefore the rear of the board (connectors) is the lower end, and the front

(controls) is the upper end.

1. ANTENNA INPUT AND TUNED RF PREAMPLIFIER

❒ 5. Install C1, 10 pF disc capacitor.

❒ 6. Install C2, 4.7 or 5 pF.

❒ 7. Install C3, 62 pF.

❒ 8. Install L1, .15 uH inductor [looks like a resistor with a green colored

body with brown, green, and silver bands].

❒ 9. Install C4, 62 pF.

❒ 10. Install L2, just like L1 above.

❒ 11. Install C5, 10 pF.

❒ 12. Clearly identify Q1, the 2SC2498 or 2SC2570A transistor. Do not

confuse it with the other transistors supplied.

❒ 13. Position Q1 as shown on the PC board layout, with the flat side facing

to the right, toward the middle of the board. Press the transistor snugly

into the PC board so that only a minimum amount of wire lead is exposed

above the board. In soldering, don't be afraid to use enough heat to make

good clean connections.

❒ 14. Install R4, 47K. [yellow-violet-orange] just to the left of Q1.

❒ 15. Install C6, 100 pF [marked 100, 101, or 101K].

❒ 16. Install R5, 470 ohms [yellow-violet-brown].

2. SA602 OSCILLATOR-MIXER and VARACTOR TUNING

❒ 17. Install R6, 270 ohms [red-violet-brown].

❒ 18. Install C7, a .001 uF bypass capacitor [marked .001, 102, or 1 nF].

In installing the SA602 IC, you may wish to use an 8-pin DIP socket rather

than soldering the IC directly to the board. Reasons for doing this might

include the peace of mind of beginners afraid of damaging the IC, or

experienced builders testing the merits of the SA602's cousin, the SE602.

However, please be aware that we have seen more service problems with

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Ramsey Electronics COMPUTEMP CT255 Manuel d'instructions Page 12