W.T. Grant Company 503 Schematic

W.T. Grant Company 503

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Product Information:
Manufacturer:W.T. Grant Company
Description:Series A

Schematics Content

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POWER SUPPLY... 105 to 125 volts, DC or 50 60 cycle AC, 35 watts. FREQUENCY RANGE... 545 to 1700 kc. INTERMEDIATE FREQ... 455 kc.

TUNING... Permeability.


- Built-in plate type. Also provisions for external antenna. No ground required.

SPEAKER 5 - inch; P.M.; voice coil impedance 3.2 ohms.
POWER OUTPUT... 800 milliwatts, undistorted. 1.2 watts maximum.
SENSITIVITY... 35 microvolts average for 50 - milliwatt output.
12SA7, converter
12SK7, I.F. amplifier
12SQ7, 2nd detector, AVC, 1st audio
50LOGT, output amplifier
35Z5GT, rectifier

SETTING THE PUSHBUTTONS - The pushbuttons may be used, after proper adjustment, for the automatic tuning of any four stations on the standard broadcast band. They can be set up in any order.

1. Turn on the radio.

2. Push out the call letters of the four stations from the call-letter sheets supplied with this manual.

3. Insert one call-letter tab in the rectangular opening in the front of each pushbutton, in any order. Press an acetate tab (supplied in small envelope) into each of the pushbuttons.

4. With the screwdriver supplied, check to see that the locking screw in the center of the tuning knob (see front view) is loose. If it is not, turn it several turns to the left (counterclockwise).

5. Press the first pushbutton down all the way. With one hand hold the button down firmly and with the other carefully tune in the desired station. Release the push button.

6. Follow this procedure for each of the three other buttons, setting each one for a different station.

7. Rotate the tuning knob'on the side of the cabinet as far to the right as it will go. Tighten the locking screw in the center of the knob. IT IS IMPORTANT THAT THIS SCREW BE TIGHTENED VERY FIRMLY,

8. The pushbuttons are now properly set for automatic tuning. Any of the four stations may be tuned in simply by pressing the proper button down as far as it will go. If you wish to reset any of the buttons for a new station, loosen the locking screw, set the pushbutton as described above, and re-tighten the locking screw.

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DIAL LIGHT - If the dial lamp burns out the set should not be operated until a new lamp has been installed. Failure to heed this caution may result in a burned-out 35Z5GT tube. To replace the lamp, first remove the buttons which hold the back to the cabinet. The Chassis View illustration shows the location of the dial lamp. Pull the lamp bracket toward the rear of the radio. The lamp can now be removed and replaced. Use a 6- to 8 - volt lamp, type T - 47.

NOTE ON TUBE REPLACEMENT Replace a defective metal 129K7 tube with another metal tube. Replace a glass 128K tube with a metal tube or with an exact duplicate of the tube now in the set.

(Refer to Chassis View for location of trimmers)

Output meter across 3.2 - ohm output load.
Align for maximum output. Reduce input as needed to keep output near 0.4 volts,

Volume control at maximum for all adjustments.
Chassis must be removed from cabinet for proper alignment.

The antenna coil assembly is made so that it is movable. When making the adjustment as given in the alignment procedure move the coil assembly very slowly. It can be moved by band or by pivoting one edge of the blade of a screwdriver in the hole and engaging the blade in the gear teeth of the coil form

After the antenna coil has been tracked at 1400 Kc, it is necessary to check the antenna trimmer (C13 - A) adjustment again at 1700 Kc. If no appreciable change in trimmer adjustment is made the coil is in track, it the trimmer requires considerable change it will be necessary to again adjust the position of the antenna coil at 1400 Kc. These two adjustments should be tried several times until no change of trimmer adjustment is required at 1700 Kc.

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Models 502 and 503 - Series A