Central Electronics DQ Altro


The «Q" Multiplier is a selectivity device for use with either the Sideband Slicer or any Receiver having an IF frequency range from ¿50 to 500 kca. Model AQ is intended for use with Model A Sideband Slicer end. converts, the Slicer to Model E. Model DQ is a Desk Model for use with any Receiver in the above IF frequency range. The unit consists of a high "Q" coil connected in a vacuum tube (6AB4) circuit so that by means of feedback, the effective "Q" of the coil is Multiplied many times. This results in a very high "Q" and a very high impedance at resonance. It may be used to increase the IF selectivity in the PEAK position, or else to put a "notch" in the IF passband in the NULL position. Basically the unit has two separate signal paths; the "Q" channel consisting of the 6AB4 with the triode section of the 6U8,and the second channel consisting of the pentode section of the 6U8. In the OFF position of the switch, the 6AE4 is disabled and the pentode section of the 6U8 is used as an IF Amplifier. With this stage of amplification, the-AP-1 is no longer required. In the PEAK position the pentode functions as a grounded grid IF Amplifier for the "Q" channel. With the SELECTIVITY control fully counterclockwise, some selectivity is added at the frequency to which the "Q" circuit is tuned. Advancing the SELECTIVITY control increases the selectivity until the circuit goes Into oscillation. At the point Just before oscillation, the bandwidth is only a few cycles. This position is useful for CW, AM, FM and SSB, by using the proper amount of selectivity. Advancing the selectivity control too far on phono reception will result in loss of intelligibility due to the restricted bandwidth. Generally more selectivity can be_used on strong and undistorted signals. If a strong heterodyne cannot be reduced sufficiently in the PEAK position, it will be necessary to switch to NULL. In the NULL position both channels are used. The desired signal and the interfering carrier is applied between grid and cathode of the 6U8 pentode and to the "Q" Multiplier channel. Due to the high order of selectivity obtainable in the "Q” channel, the interfering carrier may be separated from the desired signal by timing the "Q" circuit. This interfering carrier passes through the triode section of the 6U8 operating as a cathode follower and is cathode coupled to the pentode section. At this point the carrier from the "Q" channel is 180° out of phase, cancelling the interfering carrier in the signal channel. la actual practice, when it is desired to null out an interfering carrier, proceed as follows: CAUTION: When attempting to remove an interfering carrier on an AM Phone signal (with the Receiver in Normal reception), be sure to tune the ”Q" circuit to the interfering carrier and not to the carrier of the desired signal. Removing either one of the carriers will eliminate the heterodyne, but eliminating the desired carrier will result in severe distortion. This does not apply when the Slicer or EFO are used to reinsert carrier. The built "Q” Multipliers are shipped -using the 60 mmfd. section only on C1Q4, the TUNING capacitor. With receivers utilizing a mechanical or lattice filter, or other extremely Sharp IF system, the stator lead should be changed over to the 30 mmfd. section (3 plates) to obtain greater TUNING bandspread. When older receivers are used which have an IF passband of 20 to 25 kilocycles, both sections of C1Q4 should be wired in parallel in order to cover this range. Q Multiplier

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Servizio e manuale utente
Tipo di manuale:
Servizio e manuale utente
176.12 Kbytes (180343 Bytes)
ID del manuale:
05 luglio 1955
Documento scansionato, la lettura in parte male, non in parte leggibile.
Data caricamento:
09 luglio 2017

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