1955 - 1959 Chevrolet Radio Service & Shop Manual Supplement

(Contributed by Bill LePage)

To properly align the receiver, it will be necessary to have an output meter and signal generator.

NOTE: If any one of the tuning coils or cores have been replaced, see "Capacity and inductance Alignment Procedure" before proceeding with alignment of the receiver. If only the adjustments have been tampered with or an intermediate frequency transformer has been replaced, proceed with the alignment as follows:
 

1. First hook up an output meter to the radio receiver. Any volt meter
  which will read "A.C." can be used. Set the voltmeter in the 3 volt
  "A.C." range position and ground one lead of meter to radio
  chassis. Place the other lead from the volt meter to the speaker
  terminal of the speaker to which the "green" lead of the audio
  output transformer is connected, (speaker is item 53 and audio
  transformer item 54 on circuit diagram and parts layout).
2. Turn on signal generator and set adjustments to obtain a 262
  kilocycle signal. Connect one lead of signal generator to radio
  chassis for ground. Attach the other lead from the signal generator
  to the tube pin marked "G" on 6BE6 tube.
3. Adjust signal generator volume control so that the volt meter will
  read at about half scale.


NOTE: Radio receiver volume control must be turned to the maximum position, so that the automatic volume control circuit of the radio will not affect the alignment of the receiver.
 

4. Adjust in sequence trimmers "A, B, C and D", as shown on circuit
  diagram and parts layout, for maximum meter reading. Repeat
  adjustments to get maximum meter reading. Keep the signal
  generator volume turned down so that during adjustments the meter
  does not read more than half scale. This will result in a better
  alignment of the receiver.
5. Next change signal generator setting to obtain a radio frequency
  signal and tune signal generator to exactly 1615 kilocycles.
  Connect a .000082 mfd condenser to antenna connector and
  attach signal generator lead. Tune radio receiver to the "stop" on
  the 1600 kilocycle end of the dial. Keep the signal generator
  volume control adjusted so that output meter reads at about half
  scale.
6. Adjust trimmers "E, F and G" on circuit diagram and parts layout
  in sequence for maximum readings on output meter. Repeat for
  maximum meter readings.
 
7. Tune the signal generator and radio receiver to exactly 1000
  kilocycles and repeat adjustments of trimmers "F and G" ONLY
  for maximum readings.
8. After the receiver has been installed in the car, turn on receiver
  and tune in a weak station between 600-1000 kilocycles, with
  radio volume control turned to maximum position and the antenna
  extended to full height. Readjust trimmer ONLY for maximum
  volume.

 

CAPACITY AND INDUCTANCE ALIGNMENT PROCEDURE
FOR 987187 RADIO



This alignment procedure is to be used only when any of the following parts have been replaced in the radio; antenna coil, radio frequency coil, oscillator coil or any of the tuning cores.

The intermediate frequency alignment at 262 kilocycles is the same as outlined in "Alignment Procedure" operations 1 through 4. After completing the intermediate frequency alignment, proceed as follows:
 
1. Connect signal generator lead to a .000082 mfd. condenser and
  connect to antenna terminal of antenna socket. Mechanically
  align iron core "H" on circuit diagram and parts layout, to measure
  1 & 25/32 inches in coil from rear mounting edge of coil.
2. Tune signal generator to exactly 1615 kilocycles and tune radio
  receiver to "Stop" on the 1600 kilocycle end of the dial. Set output
  meter on the 3 volt "A.C." scale and keep signal output below 2
  volts during adjustments.
3. Adjust trimmer "E, F, and G", on circuit diagram and parts layout
  in sequence for maximum readings on output meter.
4. Tune the signal generator and radio receiver to exactly 1000
  kilocycles and adjust iron cores "J and K" for maximum output meter
  reading.
5. Reset signal generator to exactly 1615 kilocycles and tune radio
  receiver to this frequency. Then readjust trimmer "F and G" only
  until no further increase in output meter reading can be obtained.
6. After the radio receiver has been installed in the truck, turn on the
  receiver and tune in a weak station between 600 and 1000
  kilocycles, with volume turned to maximum position and antenna
  extended to full height. Readjust trimmer "G" only, for maximum
  volume.


 

 

 

 

 

 

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