The 51J-4 Communications Receiver is available in two styles.  One is a panel and shelf assembly suitable for mounting in a standard rack cabinet.  A dust cover that fits over the top of the chassis is removable from the rear.  The other assembly is in a cabinet, suitable for table-mounting.

This receiver operates in the range of 540 kc to 30.5 mc, with a total setting error and drift of less than 1 kc at any frequency within its range.  It incorporates the new mechanical filter in the intermediate frequency range to operate the desirable rectangular-shaped passband.

The operating range of 540 kc to 30.5 mc is covered by 30 one-megacycle bands that are selected by the band switch knob and indicated by a slide rule dial having graduations of one-tenth megacycle (100 kc) intervals.  The main tuning control covers each of the megacycle ranges with 10 turns of a 100 division dial calibrated at one-kilocycle intervals.

The 51J-4 receiver uses single, double, or triple conversion in tuning the entire frequency spectrum of 540 kc to 30.5 mc.  Nineteen tubes, three of which are dual, are employed in the receiver.  With the exception of the rectifier tube, all are of the miniature type.

Size and weight:

• Rack mount dimensions: 19 " width, 10 1/2" height, 13 1/2" depth
• Cabinet dimensions: 21 1/8" width, 12 3/8 " height, 13 1/8" depth
• Weight: 43 lbs.