L Sgi
a quarter wave it would be exactly a quarter wave if it were not for the loading offered by the capacity of the vacuum-tube elements. The second and more effective type of line is of the concentric type, a small copper pipe or rod being mounted inside a larger pipe and the two connected together at one end. The usual practice is to make the outer conductor slightly longer than a quarter wave and the inner line considerably shorter. A sliding sleeve over the inner conductor is then used to vary...
Thordarson Electric Mfg Co
'Pemand ' ' ftouret bu Tko dallon pHE HALLICRAFTERS organization was founded in the belief that there was room for improvement in the design of amateur radio equipment, and a definite need for an adjustment in price levels. We felt that good management and skillful engineering might make this possible. Ever since the first Sky Rider was introduced several years ago, Hallicrafters receivers have won an increasing acceptance until the organization is now the largest American manufacturer of...
cury vapor the lower the voltage at which
arc-back will take place for this reason mercury-vapor rectifier tubes should always be located so that there is free circulation of air around them for cooling. The tubes are usually rated at a peak inverse voltage which will permit safe operation at normal current in a room of average temperature. The peak current rating is based on an electron flow from the filament which will give a filament life of 1000 hours or more. In the high-vacuum types the tube voltage drop depends upon the current...
Mtc Transmitting Condensers
Compact types. Isolantite insulation. Base or panel mounting. Polished aluminum plates. Stainless steel shaft. Size of 150 mmf. with .070 plate spacing only 41 s behind panel. A model has .040 plate thickness, all others .025. A and B models rounded plates. C types plain plate edges. Self-cleaning wiping contact. MTC-35-A 35 MTC-20-B 20 mmf 2.85 MTC-35-B 35 mmf 3.10 MTC-50-B 50 mmf 3.50 MTC-100-B 100 mmf 4.60 MTC-150-B 150 mmf 5.70 MTC-50-C 50 mmf 2.40 MTC-100-C 105 mmf 2.65 MTC-150-C 150 mmf...
Schematic Symbols Used In Circuit Diagrams
f, f - filament lt 3- Grid P- Plate Pentode Vacuum Tube X-Suppressor Grid connected to filament inside the tube when It is manufactured. f, f - filament lt 3- Grid P- Plate Pentode Vacuum Tube X-Suppressor Grid connected to filament inside the tube when It is manufactured. 1 Potentiometer, Moment rheostat etc. Inductor Fixed Inductance CoHor rf. chokeJ no resistance. Actually, the angle of lag or lead depends on the ratio of reactance to resistance in the circuit. Another kind of phase...
Tcp Splitstator Types
_ Identical to single types, ex- i ijjjji. pt that stator sections are ES ii MOTIS individual. With sections in WM. fctfi - series, breakdown voltage is J doubted. C types us .038 plate spacing X types .080 plate spacing, and A types .192 spacing. CODE CAPACITY LIST TCD-250-C 240 mmf. per sect 8.00 TCD-500-C 500 mmf. per sect 9.00 TCD-100-X 100 mmf. per sect 9.00 TCD-225-X 225 mmf. per sect 11.00 TCD-50-A 50 mmf. per sect 12.00 TCD-100-A 100 mmf. per sect 18.00
Dunco Remote Control Relay
Relay type CXB51 is an ultra sensitive unit designed for direct current in the coil circuit and either direct or alternating current in the contact circuit. It has single pole, double throw contacts, making one circuit when the coil is energized and another circuit when the coil is de-energized. Thecoil hasa resistance of 10,000 ohms and it will safely carry currents up to 18 milliamperes. Adjustments are provided that will cause the relay to operate on any desired current value down to one...
Tuning Capacity
FIG. 821 TYPICAL BEHAVIOR OF D.C. PLATE CURRENT WITH TUNING OF AN AMPLIFIER leaves the grid current unaffected as the plate tank is tuned through resonance is the correct one. If the circuit is slightly out of neutralization the grid meter needle will give a noticeable flicker. With single-ended circuits having split-stator neutralization the behavior of the grid meter will depend upon the type of tube used. If the tube's output capacity is not great enough to upset the balance, the action of...
Superheterodyne Receivers
9 As has been mentioned previously, the su-perhet-type receiver differs from the simpler regenerative autodyne types in that the incoming signal frequency is first converted to a fixed intermediate radio frequency usually of from 450 to 500 kc. in high-frequency super-hets and is then amplified at the intermediate frequency prior to audio-frequency detection. Tracing the operation through the circuit, following r.f. amplification the frequency con- FIG. 609 TUNED ANTENNA COUPLING CIRCUITS TO...
Brand 1
The Perfect Lead-in Insulator PYREX No. 67104 The Perfect Lead-in Insulator PYREX No. 67104 ERFORMANCE, which alone has for PYREX Radio Insulators their present day supremacy, is the direct result of the inherent properties of the glass composition from which they are made. The high volume and surface resistance and low power loss of PYREX brand glass result in clearer signals and better distance, particularly under adverse conditions. The perfection of su rface of PYREX Radio Insulators is an...
Info Jme
Plate Current to be adjusted to 0.2 ma. with no signal TABLE I 6.3-VOLT GLASS RECEIVING TUBES Continued TABLE I 6.3-VOLT GLASS RECEIVING TUBES Continued
The Rejection Action Of The Ss Crystal Filter Circuit 1
is shown in Figs. 622 and 623. It is notable that the band-width variation at 10 times down is over a range of more than 12 to 1 with the crystal filter, and that the maximum selectivity is more than 35 times that obtained for the same type receiver with the crystal filter switched out see Fig. 602 . A filter of this type is used in the crystal S.S. superhet described in the next chapter. The crystal is connected in the bridge circuit so that counter voltage of controllable phase can be applied...
Ph Sur 1
sufficient for keying any of the pentode transmitting tubes now available. Another method of suppressor keying is shown in Fig. 1005. In this case no additional bias source is needed, the keying bias for the FIG. 1004 SUPPRESSOR KEYING OF A PENTODE TRANSMITTING TUBE The keying system is arranged to put positive bias on the suppressor grid with the key open, and negative bias with the key closed. FIG. 1005 A SUPPRESSOR KEYING SYSTEM IN WHICH KEYING BIAS IS OBTAINED FROM THE GRID LEAK method of...
Info Hsa
A transmitter utilizing bleeders dissipating wattage in order to obtain correct operating potentials thereby reducing efficiency and impairing load regulation. Before modernizing your present equipment or buying a new plate transformer why not get the dope on our new exclusive triple winding plate transformer and compare it on merit alone with others. This new exclusive triple winding plate transformer provides the utmost in flexibility. Over 30 voltages are available ranging from 400 to 1600...
Z Vru
Electron-coupled control not used on 3.5 mc. Coils A, B, C and D wound on Hammarlund Isolantite forms. Coils for amplifier plate wound on G.R. Forms, 2lfa-inch diameter, 7 grooves per inch. Coil E actually is used, a tap being taken off at 17 turns. 25 watts. A 14-mc. crystal can be used if the cathode clip is set on the proper tap. The output should be higher than when doubling from a 7-mc. crystal. Before the tuning operations are attempted, the section on Tri-tet oscillators in Chapter Eight...
L Pyc
FIG. 1428 THE SIMPLE MODULATOR USED WITH THE MINIATURE TRANSMITTER Ti VTC Type CS103 microphone transformer. 1'2 VTC Type CS34 used back-to-front to give a step-up turn ratio of 1 to 1.2. Ri 500,000-ohm potentiometer. Rs 350-ohm 5-watt resistor. ifs 25,000-ohm 1-watt fixed resistor. Ci 25 tifd. 50-volt electrolytic condenser. Cs .5 ufd. tubular-type condenser. FIG. 1428 THE SIMPLE MODULATOR USED WITH THE MINIATURE TRANSMITTER Ti VTC Type CS103 microphone transformer. 1'2 VTC Type CS34 used...
Circuit Of The Simple Fieldstrength Meter
Ci 30-fiftfd. adjustable mica trimmer condenser. Ci 35-fifjfd. midget air trimmer condenser. Cs 250-nyfd. midget mica fixed condensers. Rl 1000-ohm midget potentiometer. L 50-80 mc. 7 turns No. 14 tinned wire, 2-inch dia. 1-inch long. 25-40 mc. 10 turns No. 14 tinned wire, -inch dia. 1-inch long, 12-20 mc. 20 turns No. 16 enamel wire, close-wound on -mc i diameter bakelite tubing. 6-10 mc. 37 turns No 22 enamel wire, close-wound on -inch tube. 3-5 mc. 75 turns No. 30 d.s.c. wire, close-wound on...
Operating Position At Wbyp 1
Everything in its proper place with no unnecessary apparatus cluttering up the table. Speech amplifier and transmitter controls are at the left of the receiver. The frequency meter is at the right of the receiver with the telegraph keys. methods some typical examples of which are given later in this chapter. With remote control, the transmitter and its power supply may be located in the attic, in the basement, or in a specially built dog-house in the back yard. The receiver and control switches...
Transmitting Tube Sockets
For many years the accepted best for mounting UX and 50 Watt tubes, now also made for 5 prong tubes such as the RK28 and RCA803. All have a heavy polished nickel plated brass shell a necessity for properly supporting transmitting tubes. Contacts are one piece, of heavy cadmium plated phosphor bronze, and make firm wiping side contact with the tube prongs. Connections may be soldered directly to contact springs. FB types are for vertical panel mounting and are enclosed in black finished cast...
Jacks And Plugs
Large contact area non collapsible. TKe use of these plugs assures good contact without failure. Preferred by radio amateurs the world over. 0 395 GiantJacM s Mounting Hole. Each .25 396 Giant Plug with 10-32 Threaded 397 Giant Plug with 1 4-20 Threaded 398 Giant Plug, 1 4-28 Threaded Shank Each .25 No. 396 399 Giant Jack, 1 2 Mounting Hole .Each .25 400 Plug, 6-32 Threaded Shank, Ys 401 Plug, 6-32 Threaded Hole Each .07 403 Jack, Va Mounting Hole Each .06 No. 395 The superior electric...
matching section in the Q type antenna
just described. The open-wire quarter wave section cannot satisfy the conditions for impedance match between an antenna and feed line when these are connected to its ends, however. It is therefore necessary to obtain FIG. 1621 ANTENNA SYSTEM WITH CORRECTIVE STUB FOR IMPEDANCE MATCHING The formulas for one-half wavelength antennas given earlier in the chapter give the antenna length, A plus A, each half being a quarter wave. The stub length, B, and point of attachment to the non-resonant line,...
Magicore If Transformers
Designed to meet the demand for greater selectivity on the Amateur Bands. Modernize your present Communication Receiver by installing a set of MAGICORE I.F. TRANSFORMERS. Three stages will reduce the I.F. Channel Bandwidth from an approximate 20KC. to from 3 to 5 KC. wide, with gain equal to that of an air core amplifier. The Ultra-Selective Characteristic ofthe MAGICORE I.F. TRANSFORMERS is due to the use of a newly developed iron core composed of a magnesium-ferrous alloy resulting in a coil...
Info Mtd
0 For the convenience of its members, the League maintains a QSL-card forwarding system which operates through volunteer District QSL Managers in each of the nine U. S. and five Canadian districts. In order to secure such foreign cards as may be received for you, send your district manager a standard No. 8 stamped envelope. If you have reason to expect a considerable number of cards, put on an extra stamp so that it has a total of six-cents postage. Your own name and address go in the customary...
Info Qth
2Spaced to make coil length l 4 inches. Ll and Lz all close-wound with No. 36 d.s.c., spaced H-inch from Lz or Li. Forms are National R-39, five-prong. 111L iiu.ii-rntroiiM lt i sitkkhet 2Spaced to make coil length l 4 inches. Ll and Lz all close-wound with No. 36 d.s.c., spaced H-inch from Lz or Li. Forms are National R-39, five-prong. When everything is aligned the c.w. beat oscillator should be set so as to give about a 1000-cycle tone when heterodyning a signal tuned in on the nose. Then...
Shaft Extension Screw Lug
RELAY RACK SHELF This recessed shelf will fit any standard relay rack, and is particularly useful for supporting portable equipment, instruments, test equipment, etc., Type RRS. List Price 4.00 COIL CHART FRAMES Nickel Silver Chart Frames are available in the sizes shown above. The largest frame is the same as that used on the AGS, the medium frame is the same size as that on the FB-7, and the smallest is the same as the HRO frame. Prices include celluloid sheet to protect the chart. Size A....
Steatite Antenna Insulators
Because of their exceptional strength, and exceptionally low moisture absorption, Birnbach Steatite Antenna Insulators are highly recommended. Will with- . path is long and the No 470-471 small as consistent with the strength required. A smooth white glazed finish prevents accumulation of dirt and ice. 470 Steatite Antenna Insulator, 7 Long .50 471 Steatite Antenna Insulator, 12 Long 70
R F Plate Chokes
At last The many advantages of single layer winding are available in chokes for the plate circuit of transmitters up to 1000 M.A. plate current. These chokes are wound over ceramic tubes and coated with special moisture resisting enamel. Ample space at ends to prevent flash-over. Four sizes to cover six main amateur bands Tube manufacturers insist that exact value of filament voltage is imperative for longest life consistent with maximum output. OHMITE Rheostats provide close control in the...
Classc Af 1
does the i.f. silencer method. They are ineffectual with shock excitation of a previous high-selectivity circuit. Refer to article by H. A. Robinson, Feb., 1936, QST, for details. Another type of output circuit for taking out background noise of amplitude lower than the signal amplitude is diagrammed in Fig. 633. This arrangement is also helpful in restoring aural intelligibility to code signals after they have passed through circuits of extreme selectivity, which tend to remove the keying...
Modified For Use With Twovolt Tubes
Components have the values given in Fig. 713-A tcith the following additions Au, 50,000-ohm potentiometer R12 5000 ohms, 1-watt rating Ru, 10-ohm rheostat RFCi, same specifications as given in Fig. 707. Ril and Rl2 constitute the gain control circuit in the r.f. amplifier fiia is used to make certain that a small amount of grid bias will be applied to the tube even though Rn is set at its minimum-bias end. Filament supply may be from an Air-Ceil battery or from two dry cells connected in...
Grounded To The Chassis 1
Ci, Cz Ganged condensers9160-pnfd. each National type PW tuning unit . C3, C4 50'fififd. air trimmers National type UM-50 . Ct 25-finfd. midget variable Hammar-lund MC-25-S . Cq - 50-nnfd. midget mica condenser. C7 100-iiufd. midget mica condenser. C9-C20, inc. 0.01-ufd. paper condensers, non-inductive. C21 140-mifd. variable in B.O. unit . C22 250-p.fifd. mica condenser in B.O. unit . C23 B.O. coupling condenser, about 5 finfd. see text . Co4, C25, C26 100-pnfd. mica condensers. C27 C28, C29...
Atr 1
The ACT-40 Transmitter is nominally rated at 40 watts output on either 'phone or c.w. The r-f system employs an RCA-47 as a crystal oscillator, an RCA-802 as a buffer or doubler and two RCA-801's as final amplifiers. Coils are available for the 20, 40, 80 and 160 meter amateur bands. The a-f system employs an RCA-57 and RCA-56 as speech amplifiers, 2 RCA-45's as drivers and 2 RCA-801's as Class B Modulators. Individual units of the ACT-40 may be purchased separately. The price complete for...
Classb Mod A 1
Ci 20-fifd. low-voltage electrolytic. Cl 0.02 fifd. C5 0.I nfd. Co 0.005 fd. ' 7, Cs, c9 Three-section electrolytic. Li, I. . 100-ma. filter chokes. Lz 20 ma. filter choke. Ti Any good audio step-up transformer, about 3-1 turns ratio. 12 Coto C I 402 Triadyne output transformer. Coto C I 403 Class-B output transformer. Ti Power transformer. T 203-A filament transformer. J Plate meter jacks. COMPLETE CIRCUIT OF THE 250-WATT DRIVER-MODULATOR AND PRE-AMPLIFIER UNITS COMPLETE CIRCUIT OF THE...
B Fnq
FIG. 611 CIRCUITS FOR TWO TYPES OF WAVE-TRAP IMAGE REJECTORS Type A is fitted with plug-in coils and is intended for use external to the receiver. The coils, L, are wound on lYz-inch diameter plug-in forms, 30 turns for the 3.5-mc. range9 14 turns for 7-mc.f 7 turns for 14-mc. The tuning condenser C is a 140- or 150-nnfd. midget, SIT' is a single-pole single'throw shorting switch. Type B is more adaptable to mounting within the receiver, coupled inductively to the antenna lead as shown or...
Rz
FIG. 1308 TWO TYPICAL METHODS OF APPLYING QUENCH VOLTAGE TO THE SUPERREGENER-ATTVE DETECTOR Circuit is one of the most successful types using a triode detector while that at B shows what is probably the most satisfactory for use with a screen-grid detector. Typical values for the components marked are Ci .002 to .004 fifd. Cb .002 yfd. C2 .1 to .5 jfd. Rl 100,000 ohms. C3 .1 fifd. 2 50,000 ohms. Ci .001 nfd. R3 50,000 ohms. Circuit B can be understood more readily if it is noted that the screen...
Info Ovm
A flexible time saving alignment tool. When used with a reliable oscillator and output meter, misaligned circuits are immediately indicated, showing whether an increase or decrease in capacity is needed to align the circuit. Inserting the Polyiron end into a coil has the effect of adding capacity while the brass end has the effect of reducing the capacity. Proper alignment is indicated when both ends, upon being separately placed in the field of the coil, decrease the output of the receiver....
Code Practice Oscillator
This small audio oscillator is suitable for either code practice, or as an audio signal source for ICW on the Ultra High Frequency Bands. A type 30 tube is used, and four flashlight cells in the case provide filament and plate current. Type CPO, without batteries or tube. List Price, 6.00 Type IFCO Oscillator air core only List Price, 5.CO NATIONAL COMPANY, INC., MALDEN, MASS.
A General View Of The Watt Transmitter And The Antenna Tuning Unit 1
capacities and its own distributed capacity. The single exception is the 1750-kc. coil, where the physical dimensions of such a coil would be so large as to make the untuned coil impracticable with ordinary coil forms. Therefore for this band only an auxiliary condenser, C12, is used to tune the grid circuit. The plate circuit of the final stage uses a split-stator condenser with grounded rotor. The plate coil is tapped at the center and fed d.c. through an r.f. choke. The amplifier is...
Company
466H West Superior Street Chicago, Illinois Licensee of Johnson Laboratories, Inc. These devices manufactured under one or more of the following U. S. Letters Patents 1887380, 1940228, 1978568, 1978599, 1978600, 1982689, 1982690, 1997453, 2002500 2005203, 2018626, 2028534, 2032580, 2032914, 2035439. Other patents pending. Aladdin Polyiron Technical Bulletin 536 ALADDIN r-f and i-f coupling devices utilize inductors consisting of a winding on a Polyiron core, thereby obtaining an advantage over...
Standoff Insulators
The original Johnson Stand-Off Insulators are characterized by perfection of ceramic design, logical proportions and range of sizes, accuracy, and, most important, a very superior quality of porcelain and hardware. The new Bee-hive and straight side insulators styles B and C have unbreakable cadmium plated drawn steel bases and as usual mount in very little space. Jack types are available in many sizes. Specify white or brown glaze.
Info Tlr
High gain amplifiers will operate much more quietly when composition units are replaced with WIREWATTS, having no heat or voltage characteristics. Same size as composition units will fit most radio circuits. Rated at one watt, furnished in 42 values from 100 to 25,000 ohms. Used to provide an electrical center where filament transformer has no center tap of its own. Furnished in BROWN DEVIL, RED DEVIL or WIREWATT types, as shown below. Range List Type Watts ohms Price Brown Devil 10 10 to 200...
Classc Amp 1
FIG. 1103 CIRCUITS FOR THREE METHODS OF MODULATION A and B are for plate modulation, C for grid-bias modulation. FIG. 1103 CIRCUITS FOR THREE METHODS OF MODULATION A and B are for plate modulation, C for grid-bias modulation. In A of Fig. 1103 is shown the circuit of what is known as the Heising or constant-current system of plate modulation. The plate power for the modulator tube and modulated amplifier is furnished from a common source through the modulation choke, L, which has high impedance...
Transmitter To Fit It For Gridbias Modulation 1
Legends on components are the same as those given in Chapter Nine. and its center-tap is not connected directly to ground. Adjustable bias is taken off a voltage divider across a 400-volt supply so that the modulated-amplifier filament can be biased positive with respect to ground, which is the same thing as biasing the control-grid negative with respect to the filament. In adjusting a grid-bias modulated amplifier, the grid-bias voltage is initially set slightly more negative than a cut-off...
Lowloss Coil Forms
The transmitter coil forms listed below are low-loss ceramic coil forms designed for high efficiency and should not be confused with ordinary porcelain forms. A data sheet, supplied with each coil form, makes it extremely easy to determine the correct wire turns to use on any of the amateur bands. XR-10A, Low-Loss Ceramic, 20 or 40 meter. XR-12A, Low-Loss Ceramic, 160 meter. XR-13, Isolantite 1W did. x 3 2 long . RECEIVER COIL FORM. These well-known R-39 forms are machinable, permitting the...
First Det 1
FIG. 612 SUPERHET CONVERTER CIRCUIT USING AN ELECTRON-COUPLED OSCILLATOR AND CONTROL-GRID INJECTION FIG. 612 SUPERHET CONVERTER CIRCUIT USING AN ELECTRON-COUPLED OSCILLATOR AND CONTROL-GRID INJECTION separated. Such screening is also effective in preventing some noise pick-up at the receiver's input circuit. A tuned antenna circuit or radio-frequency amplifier not only improves the image ratio, but is also effective in improving the signal-to-noise ratio of the receiver. Some compromise is...
Info Ljn
14-Tube Communications Receiver Kit Utilizing the MEISSNER Completely Assembled Tuning Unit Especially designed for the Radio Amateur who wants a receiver to cover all the bands. The five, ten, twenty, forty, eighty, one hundred and sixty, and the broadcast band. Every proven development in circuit design is incorporated. Crystal Filter Beat Frequency Oscillator with cut-o-it switch and pitch control Noise Silencer Circuit Vuria ble Electrical Band Expansion Amplified A.V.C. lt Variable...
Two Valve Radio
Figs. 705 to 710, inclusive, show the construction and circuit of a more sensitive type of simple regenerative receiver in which a pentode type screen-grid tube is used as the detector and a triode as audio amplifier. This set uses a tuning system giving more uniform band-spread than the simple parallel-condenser method of the previous receiver. The tuning system is that of Fig. 603-D in Chapter Six, using a band-set condenser across the whole coil and the band-spread condenser across part of...
Hammarlund Mcd 50 M
S Ideal variables for ultra-short wave and s'10rt wave tuning, laboratories, etc. Iso-. Jvvft lentlte insulation. All contacts riveted or r M soldered. Vibration proof. New improved Pr Hammarlund split type rear bearing, and I 1 noiseless wiping contact. Cadmium plated 1__r . soldered brass plates. Shaft V - MC-325-M 325 MC-250-M 260 mmf 3.00 MC-200-M 200 mmf 2.75 MC-140-M 140 mmf 2.50 MC-140-S 140 mmf 2.50 MC-100-M 100 mmf 2.25 MC-100-S 100 mmf 2.25 MC-75-M 80 mmf 2.00 MC-75-S 80 mmf 2.00...
Esico Does Not Fray
The average iron loses a considerable portion of its heat only a short period after it is put into operation. The element and oxidizing causes this difficulty. ESICO has gone a step forward by using NICHROME Vin the construction of the electric soldering iron element and reducing this factor to a negligible level. Good Esico soldering irons give the full wattage rating during their long life. Electric cords fraying and shorting cause much inconvenience to many amateurs and in some cases result...
This Chapter 1
tion. Plate modulation might be added later to give full 'phone output, employing the grid modulator in a driver unit for the Class-B modulator. High-level plate and suppressor-grid modulation systems are the most tolerant in adjustment and maintenance. Grid-bias modulation is somewhat more complicated, as is also the Class-B linear stage with low-level modulation. The Class-B linear is used by amateurs to only a limited extent. Audio units for simple transmitters can be built up bread-board...
Aerovox Corporation
70 WASHINGTON STREET, BROOKLYN, N. Y. Sales Offices in All Principal Cities AMATEURS Don't be deceived. 38 more copper content does count. For 41 years the name Thordarson on a transformer has meant full quality at the fairest price. The largest exclusi' manufacturer of radio transformers challenges all competition. Thordarson's workmanship, production and perforr ance have always led. When better transformers are needed, Thordarson builds them. Because of its full conte transformer building...