• UNITED TRANSFORMER CORP

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- E. R. Roeschle in K9QYI 5 117 N. Hartman Drive Ind ianapolis 26, Ind. Precision Audio Attenuator It is very desirable to use an attenuator for all types of audio work, whether in the hi-fi field, in checking a modulator. or in investigating a new clipper or limiter. This professional quality attenuator was designed for these purposes and was further designed to use the standard 5% tolerance carbon resistors. Since the resistors were used in pairs in parallel, the 5% is reduced a little so that perhaps 3% tolerances arc reached in the overall result. Ilr-§~~~~--o-G~~~GT SI GNA L TTENUATOR AMPLIFIER NERATORf SET TO I VOLT SWITCH IN- ATTENU ATION UNT IL OUTPUT 15 ALSO I VOLT f lG. 1 Since the attenuator has a total of 100 decibels total attenuation, it is necessary to keep the input and output far apart and use an enclosed metal box to prevent fecd-thru. A long metal box with the input on one end and the output on the other and all the switches in a straight line between them is recommended for construction. Also, the at- a pi-section or a short bypass. The switches will carry very little current and can be of lightweight construction and should be easily operated to keep from moving the entire box, since the whole unit is not very heavy. The meter and the input resistor will aid in the establishment of an initial level, and db can then be set in as dh below, say, 1 volt. The meter can be one of the small VU meters currently available, or the adjustable resistor and meter can be eliminated if a metered output is available from your signal generator. The attenuator must aways be terminated in 600 ohms, but since a proper termination is usually not available, a 600 ohm load is available at the output and can be switched in as desired. The normal high input impedance of amplifiers will not shunt the output enough to disturb the calibration. When feeding the output into a carbon mike input, the input impedance should be adjusted to 600 ohms with aid of a resistor in parallel with the input, or a resistor in series with the ca rbon mike input. Measure with an ohmmeter to be sure, and then connect the attenuator output. 20 20 20 10 10 10 4 3 2 IN f ----UmU - --U ---U -nU---U---~- - --U---Um/ou T IK 47 K 4.1 K 47K 1.5K L5K 1.5K 390 360 180 91 82K . 2K . 2 K 2K 2K 2 K 110 0 510 620 (M 9 c ~ '" / FIG.2 tenuation sections have been designed in the form of pi-sections so that the resistors can be supported by the switch terminals and a straight length of No. 12 copper wire which passes thru as the ground from the input to the output ends. Protect the resistors from excessive heat with long nose pliers while soldering. The switches are of the double pole double throw (d pd t) type and alternately switch in To measure amplifier gain, for example, the signal generator is applied, and the output adjusted to 1 volt at the desired frequency, Then the output of the amplifi er is monitored, and when the output is also 1 volt, the attenuation of the attenuator is the gain of the amplifier. (See Fig. 1) This is the most straightforward way of using the attenuator in making amplifier gain measurements. . . . K9QYI 22 73 MACAZIN E
, • c one ose / u.t· -band HAS EVER BEEN , • BE FOOLED BY IMITATION! BE MISLED BY ADVERTISING CLAIMS! The original all metal encased trap was first produced in 1957 by Mosley for use with the World Famous TA·33. The Mosley trap design has been imitated by many manufacturers of amateur antennas. This is both a compliment and proof of the outstanding engineering built into every Mosley Multi· Band Antenna. antennas... r-1o n tJeO::-t l%e .------ '.-. JI&,.IB¥ MUL TI· BAND ANTENNAS have been rove best , Used by HAMS all aver ;he world! f) Specified by the U. S. Government . every test! I • Produced for Military Insta llations ! tChosen by "Vanguord" and "NASA" ! When your communications need a dependable antenna ••• Get The Finest ••• Get A Mosley ! 4610 NORTH LlNOBERGH BLVD. BRIDGETON. M ISSOURI. 63044 "'- &"'!'
Page 2 and 3: • AUDIO & POWER TRANSFO R M E R S
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Page 11 and 12: SOLID STATE "SCOOP" FROM GONSETJ FI
Page 13 and 14: "BEAMED-POWER" ANTENNAS and ANTENNA
Page 15 and 16: jammers usua lly off their mark bec
Page 17 and 18: NUVERTER @ 2 and 6 Meter Converter
Page 19 and 20: 1--- COPPER - CL AD BAKELITE 3'1/ 2
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Page 23: Frank says even filament voltage ca
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Page 29 and 30: watts of audio from the modulation
Page 31 and 32: • U£ - GPR-92C GPR·92 II COMPLE
Page 33 and 34: Eugene Fleming W40 HMK Box 884 Gra
Page 35 and 36: MODEL TA-36 TR.I1J for 10·15·20 m
Page 37 and 38: • MOD.ELTA-33 ... - - -- ~~~f~o r
Page 39 and 40: 5 BANDS , 400 WATTS HOME ,STATION M
Page 41 and 42: Details of tra nsceiver installatio
Page 43 and 44: patch consists of the coil, one or
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Page 47 and 48: Det roit, Michigan: " Does an excel
Page 49 and 50: 1000WATTS..WITH WHEELS The mobile 5
Page 51 and 52: AMATEUR NET Th e new Model 2-LF Low
Page 53 and 54: Assembled & tested, complete with s
Page 55 and 56: c EMITTER CO NNECTIO N TOP VIEW ALL
Page 57 and 58: SERVICE r • TESTED EQUIPMENT from
Page 59 and 60: BRYAN EDWARDS, JR. "T he from Kid T
Page 61 and 62: Coil T ab:e Transmitter L I- 6 turn
Page 63 and 64: Solid conductor hook up wire Strond
Page 65 and 66: truly portable, the other is not po
Page 67 and 68: should be kept as there are individ
Page 69 and 70: voltage and current values into the
Page 71 and 72: some mean s of attaching guy wires
Page 73 and 74: YOU KNOW ABOUT THE • MOBILE POWER
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I'm sure it cou ld be done, outboar
Page 79 and 80:
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5B-33 and MP-l0 Myron Pogue W6VAX S
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for checking your frequency before
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Kenneth L. Mills K8AJD 3013 Cameran
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THE NEW IN STOCK AT • MODEL SW350
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SPECIAL SPECIAL SPECIAL Radio Han d
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Kentucky DXpedition Hammarlund pull
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, Letters Dear Wayne, Last May I wa
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INDEX TO ADVERTISERS To aid you in
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Propagation Chart GMT - EASTERN UNI
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• UNITED TRANSFORMER CORP

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