Figure 4. A 10/1 Board.

Calibration Procedure For Radio Test Set, Models 2947 And 2947A And Model 2947 Page Navigation
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TB 9-6625-152-24

(3) Attach extension wire to TP3 (fig. 4).

NOTE

On early boards TP3 did not exist. If TP3 is nonexistent attach

extension wire to IC1 pin 7 (fig. 4).

(4) Route wire through hole in RF lid and place RF lid back in position. Secure lid

with two screws.

(5) Connect oscilloscope and multimeter to extension wire. Set multimeter for DC

measurement.

(6) Press TI [RX TEST].

(7) Slowly advance L1 adjuster (fig. 4), observing waveform on oscilloscope.

Frequency should decrease and finally become zero as A10/1 locks to 90 MHz 3rd local

(8) Record multimeter indication (V1).

(9) Continue advancing L1 adjuster (fig. 4) until lock is lost and multimeter

indication increases further.

(10) Slowly unscrew L1 adjuster (fig. 4), observing oscilloscope waveform frequency

decreasing, until lock is regained when frequency becomes zero.

(11) Record multimeter indication (V2).

(12) Adjust L1 (fig. 4) for a multimeter indication of (V1 +V2). Oscillator should

lock to 90 MHz, in the middle of its capture range.

(13) Remove TI RF lid and remove extension wire.

(14) Replace and secure TI RF lid.

(15) Press TI [MEM] key and recall memory 01.