Monarch Mfg. Co. 10
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|Manufacturer:||Monarch Mfg. Co.|
CALIBRATION. Four sets of coils are used in Standard Model 10s, five sets in Marine Models. The escutcheon on the Wave Changing switch gives the Megacycle coverage of each band and the Main Tuning Dial shows approximate dialings for frequencies within each band. The bands on the tuning dial are labelled the same as the Wave Changing Switch, so as to facilitate locating the proper scale. The 12-4.3 M.C. and 4.4-1.5 M.C. scales are above the center of the dial, the 220-12 M.C. and 1.6-.54 M.C. (Broadcast Band) below. The top edge of the dial has a standard 0-100 degree scale for use on extra bands and for accurate logging. For details of Band Spread dial calibration, see Band Spreader paragraph below.
The Antenna Trimmer is to keep the r.f. stage resonant with the detector. Its position will vary somewhat for different dial settings and a careful operator will always check its adjustment on each signal. The right setting is the point at which maximum signal is heard. Two such points may be found if the Trimmer knob is rotated over the entire scale. They are identical, use either.
When regeneration is too far advanced (to right) the receiver will oscillate at the resonant Trimmer setting. this makes it difficult to determine the proper Trimmer setting, and a much simpler way to set it right is to proceed as follows. Turn Regeneration and Volume all the way on and set Wave Change Switch at some band other than broadcast, say the 4.4-1.5 M.C. Band. Set the tuning condenser at about 70 degrees on the top scale. Then turn the trimmer rapidly over a wide arc. A "click" or "hum" should be heard int he speaker. Now place one hand on Regeneration Control and the other on the Trimmer. Keep turning the Trimmer rapidly back and forth across the "click" point, meanwhile gradually reducing Regeneration by turning this control slowly to the left. A point will be reached where the Trimmer will no longer cause a click but instead will bring in a light background hiss. This indicates sensitivity, and means that both Trimmer and Regeneration are at their proper settings. Now turn Main Tuning Dial until signals are heard, then check Trimmer setting on the signals. If a "Squeal" is heard on the signal, there is too much regeneration. Always keep regeneration enar the "hiss" point.
THE BAND SPREADER. The non-amateur operator will find the Band Spreader useful mainly as a vernier for tuning in short wave stations. For use in this way, set the Band Spread Dial with the needle vertical (at 50). An equal amount of adjustment to right and left will then be obtainable. Short wave stations can be located with Main Tuning Dial, then accurately centered with the Band Spreader.
To the amateur, we offer a receiver having an accurate calibration of the amateur bands. Note that on the dial the letters (A), (B), or (C) appear alongside the meter marking for the band. These letters refer to adjustments which can be made on the Band Spreader cam arm in the rear of the set. Remove the back of the receiver, and note the mechanical action of the Band Spreader. The Band Spread Dial drives a pivot that lifts the tuning condenser extension arm up and down. There are three threaded holes in the cam arm in which the pivot screw with its bakelite washer assembly may be fastened. The one nearest the dial shaft, or center of rotation is "A", the center hole is "B" and the outside one "C". All receiver are shipped with the pivot on "B", which is best for vernier purposes and fits the 40 and 75 meter bands. The operator can easily change it if one of the other adjustments is desired.
HOW TO GET AN ABSOLUTELY ACCURATE SETTING ON THE BAND SPREADER. Suppose your Xtal is ground for 7050 K.C. (7.05 M.C.) With the pivot on adjustment "B", set the Band Spread Dial on the mark between 7.01 and 7.1 M.C. The Wave Change Switch, of course, should be on the 12-4.3 M.C. Band. Then, with the Main Tuning Dial, tune in the vicinity of 7 M.C. until your own transmitter frequency is picked up. This will give the proper "tank" setting to make the Band Spreader read accurately ont his band. The same procedure would of course be followed for any frequency on this band or on the 20 or 75 meter phone bands. If the transmitter frequency does not happen to be an even figure for which there is a dial marking, the position of the Band Spread Dial can be closely estimated.
SPREADING THE WIDE BANDS, - 80 and 160 METERS. On adjustments "C" the Band Spreader covers a little more than half of each wide band. If the Band Spreader is adjusted to "0" on the transmitter each side of the frequency is on the 80 meter band, and 80 K.C., to each side on the 160 meter band. If the station's frequency happens to be at one edge of the band it may be more desirable to set the Band Spreader for the edge also instead of at "0". The wide bands are marked + and - K.C. to indicate the high and low frequency ends of the bands.