. QST . est tiré de la ligne de 60 cycles. Le marqueur de fréquence contient sa propre alimentation, composée d'un transformateur de filament 1-Am-pere de 6.3 volts, d'un redresseur demi-ondurien et d'un filtre de résistance-capacitance composé de ci. d, et RI.protection contre les courts-circuits à la masse assurée par le couplage de condensateur de masse, C12,dans le circuit de sortie. L'oscillateur à quartz utilise un circuit d'oscillateur Pierce couplé à des électrons 6AK5 pentode inan, avec l'écran du pentode servant de plaque de triode équivalent alors que la sortie vers le multi-vibrateur est prise de la plaque du

• Contributeur: Reading Room 2020
• ID de l’image: 2CRNAN0
• Taille du fichier: 7,2 MB (232,2 KB Téléchargement compressé)
• Autorisations: Modèle - non | Propriété - non
• Dimensions: 2525 x 990 px | 21,4 x 8,4 cm | 8,4 x 3,3 inches | 300dpi

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. QST . is taken from the60-cycle line. The frequency marker contains itsown power supply, consisting of a 6.3-volt 1-am-pere filament transformer, and a half-waveselenium rectifier and resistance-capacitancesmoothing filter comprised of Ci. d, and Ri.Protection against short circuits to ground isprovided by the ground coupling capacitor, C12, in the output circuit. The crystal oscillator uses a 6AK5 pentode inan electron-coupled Pierce oscillator circuit, withthe screen of the pentode serving as the plate ofan equivalent triode while output to the multi-vibrator is taken from the plate of the pentode.The frequency of oscillation can be adjusted overa small range by means of the variable capacitorsCs and d. Capacitor d is used to raise the fre-quency, whereas C3 lowers the frequency slightly.Both of these capacitors are mounted on a singleceramic base as a double trimmer, and each hasa capacitance range of from 10 to 170 /x^f- Aseries capacitor, C5, was used to reduce the 50-Kc. MULTIVIBRATOR. Fig. I — Circuit of the 50-kc. frequency marker. Resistors are 3^-watt composition unless otherwise specified.Capacitances in nfii. except where specified otherwise. Ci, C2 — Electrolytic. Ce, C7, Cs, C12 — Ceramic or paper. Cs, C4 — Dual ceramic-mounted trimmer. CRi — 75-ma. selenium rectifier. Cs, C9, Cio, Cii, Ci3 — Mica. Si — D.p.s.t. slide. Except for the 115-volt a.c. source of power, it isentirely self-contained in a standard metal case, 3 by 4 by 5 inches in size. It uses a low-frequencycrystal, such as are now readily available on thesurplus market in FT-241 or FT-243 holders fortwo dollars or less. Circuit As the wiring diagram. Fig. 1, shows, themarker comprises a OAKS crystal-controlledoscillator, followed by a ()U8 triode-pentodefrequency-controlled multivil)rator adjusted toprovide marker frequencies at intervals of 50 kc.Output is ample for communication-type receiv-ers up to 30 Mc. * 22 Temple Street, Belmont 78, Mass. maximum capacitance of C4 to a

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