FIG

1606 SEVERAL SUGGESTIONS FOR COUPLING THE END OF VOLTAGE-FED ANTENNA The pi-section network mentioned previously is used at B and E. The end-fed antenna has some advantages over the center-fed arrangement since it is usually possible to arrange it so that an appreciable portion of the antenna is in clear space and fairly well elevated. However, the portion of the antenna which is brought in to the transmitter is at high r.f. potential, which is undesirable. The chief disadvantages of the...

Sangamo Mica Condensers

Available in capacities from .00004 to .0005. Type C Condensers. Actual size. Available in capacities from .00004 to .003. Type B-10 Condensers. Available in capacities from .00005 to .01. Also available in 2500 v. test, capacities .00005 to .002. Type BE-10 and BE-25 Condensers, supplied with insulated mountings as shown. TYPE E PORCELAIN CASE CONDENSERS Available in capacities from .00005 to 0.1, voltages up to 12,500. ALL RATINGS LISTED IN OUR NEW BULLETIN...

Coil

FIG. 926 ALTERNATIVE OSCILLATOR GRID CIRCUIT CONNECTIONS FOR SELF-CON-TROLLED OPERATION Shifting the cathode coil to an appropriate socket and plugging in either a crystal or grid condenser gives a choice of either crystal or electron-coupled operation. The grid condenser, C8, is a 250-fififd. receiving-type mica condenser. between oscillator and amplifier so that interstage shielding is unnecessary. All sockets are Isolantite wafer type. Three 4-prong sockets are required, for the e.c. cathode...

Not of the ten words per minute variety

But they are slow enough so that there is no mistaking what he says. The good operator does not sit down and send a long call when he wants to work someone. He Ustens in. He covers the dial thoroughly. The fellow that is admired for his good operating is the one who is always calling some particular station instead of using the inquiry signal. Because he listens until he hears someone to work and then goes after him, our good operator gets his man nearly every time. A good operator chooses the...

B C

Type C Midget i-f Transformers Type D Constantly Variable B'tclZZr Type C ALADDIN Polyiron i-f transformers are designed for auto, home, and portable receivers in which space is limited. The Litz-wound coils and low-loss dual mica trimmers are contained in a small copper shield only 1)4. high by 1 J g square. The gain of Type C transformers in circuits employing metal or metal-glass tubes averages better than the leading types of air-core coils, while the selectivity is distinctly better. Metal...

Junior Hro Receiver

For those who require the high performance of the Standard HRO but do not need its extreme versatility, the HRO Junior is offered. The circuit and mechanical details of both receivers are identical in every respect, but the lower priced model has been greatly simplified by omitting the Lamb Single-Signal crystal filter, the S meter, and by designing coils for continuous band spread only. Although these omissions do not greatly restrict its usefulness, they make it possible to price the HRO...

Practical Radio Communication

Principles Systems Equipment Operation Including Short-wave and Ultra-short-wave Radio 754 pages, 6x9, 435 illustrations, flexible, 5.00 By Nilson and Hornung, well-known radio experts, instructors, writers. This book covers the requirements for all classes of radio operator's license examinations, treats long, medium, short, and ultra-short-wave radio, includes all classes of radio stations is in general a complete text on practical radio communication based on a theoretical introduction....

Ask Your Utc Distributor For These Units

HIGHER VOLTAGES, more current at no increase in cost Primary 105, 115, 220, 230 volts A.C. 50 60 cycles. PA-110 515 or 625 each side of center at ZOO MA 400 VDC or 500 VDC. PA-3 - ----------S 6.00 PA-111 750 or 950 each side of center at 350 MA DC voltage 600 or 750. PA-4 - 10.80 PA-112 1250 or 1500 each side of center at 500 MA DC. pa-113 1750 or 2100 each side of center at 500 MA DC. PA-I14 1750, 2350, 3000 or 3500 each side of center at 500 MA DC. voltage 1500, 2000, 2500 or 3000, UTS mtg....

Construction Of Typical Audio Sections And Adjustment For Proper Modulation

The general design principles outlined in the previous chapter serve as the basis for an almost infinite variety of transmitter combinations. Descriptions of every possible arrangement that might be used for amateur 'phone would fill a book even larger than this one. A group of established types, which includes the combinations most generally adapted to amateur use, with r.f. sections for both the high- and ultra-high frequency 'phone bands as described in Chapters Nine and Fourteen, will be...

Hovac

FIG. 1507 REPRESENTATIVE POWER-SUPPLY ARRANGEMENTS FOR DIFFERENT TYPES OF TRANSMITTING TUBES FIG. 1507 REPRESENTATIVE POWER-SUPPLY ARRANGEMENTS FOR DIFFERENT TYPES OF TRANSMITTING TUBES All these diagrams will give adequately-filtered d.c. output for the different classes of service. They are explained more fully in the text. Many other arrangements are possible. Control switches should be inserted in the transformer primaries at the points marked x to permit the filament supplies to be turned...

Trains You To Meet New Code Requirements

For Years the Dominant Source of Code Training and Telegraph Technique This famous SYSTEM is backed by a Quarter Century of Success in training Amateurs and Commercial Operators who could be satisfied only with the best You Can Learn Code RIGHT, from the beginning as you will be using it on the air, or obtain your commercial license and qualify for a good job by taking CANDLER TRAINING in your own home, as McElroy, Jean Hudson and many others have done and are doing. It is surprisingly easy and...

Dynamotors

Dynamotor 32 350 volt, ball bearing, 80 mills. Special 8.00 24-1500 Gen. Elec. 2yi kw. output 95.00 WE Model 1918 Field Telephone Set, Magneto ringing, Battery talk Army dynamotors, Burke, 12 volt to 750 volt, ball bearing. 200 mill Navy Aircraft Dynamotor, Gen. Elec., new 24 1000 volts, 1 amp., extended shaft with pulley, can be driven by motor, or propeller, giving 24 volts output for filament and 1000 volts for plate or driven by its own input of 24 volts. Value 250.00. Our special price. ....

Iov

Where E is the desired full scale voltage and I the full-scale current reading of the instrument in milliamperes. To increase the current range of a milliammeter, the resistance of the shunt, Fig. 1710-B, can be found from the formula where the letters have the same significance as before. FIG. 1712 COMBINATION MULTI-RANGE OHM-METER, MILLIAMMETER AND A.C.-D.C. VOLTMETER R shunt to compensate for resistance of rectifier (integral with meter when self-contained rectifier is employed). Rl 650-ohm...

Principles Of Regenerative And Superheterodyne Types

Complete receiver circuits represent what might appear to be an infinite variety of types, and therefore are likely to be confusing when compared with each other. However, each is made up of combinations of elements which, taken by themselves, break down into a relatively small number of basic units. The purpose of this chapter is to describe the design features of these elemental units which can be combined in different arrangements to make up different types of receivers, and to show how...

Of Four Popular Bandspread Tuning Systems

Ratio can be chosen to give good band-spreading on each band. The series-condenser method is shown at B. As explained in Chapter Three, the total capacity of two condensers in series is less than that of either. C again is the tuning condenser. It should have 10(Wfd. or more maximum capacity. C is the band-setting condenser and is preferably small, perhaps 25 id. The maximum-minimum capacity ratio in the circuit will be determined by the setting of C The minimum capacity changes very little for...

Tubes

From left to right the tubes are oscillator, mixer and r.f. amplifier. The appendage on the rear is the output i.f. transformer from the mixer. In its final form the converter mould be fitted with a good vernier dial. The process is greatly simplified if an i.f. amplifier in the form of a broadcast or high frequency superhet is already available. For the moment we will assume this to be the case. The first step is to set the i.f. amplifier at the frequency chosen and connect to it the output...

L

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

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

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

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...

The Rejection Action Of The Ss Crystal Filter Circuit

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

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

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

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...

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

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

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

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...

6k7 Regenerative Receiver

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

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

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

Superheterodyne Band Spread

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

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

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

Transformer Utc

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...

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...

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.

General View Of The Watt Transmitter And The Antenna Tuning Unit

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.

Classc

Grid Suppressor Modulator

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

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

Superhet Receiver

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...

6l6 Transmitter

6l6 Transmitter

One line between staqi AS THE GROUNDS SHOULD BE MADE FIG. 907 WHEN THE TRANSMITTER IS BUILT ON INSULATING MATERIAL, GROUND LEADS FOR EACH STAGE SHOULD BE BROUGHT TO ONE POINT, WITH GROUND CONNECTIONS BETWEEN STAGES MADE AS SHOWN ize a triode amplifier. It is often also responsible for oscillation in screen-grid amplifiers. Practical Examples of Transmitter Design The following examples of oscillator, amplifier and complete transmitter construction have been selected to illustrate different...

Two Valve Radio

Valve Radio Circuit

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

6l6 Modulator

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

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...

Rms

R-S-T Rack Radiation Angle 50, 320 Radiation Resistance 44, 303 Radio Frequency Chokes 43 Radio Frequency Radio Frequency Resistance 37 Radio Inspection Districts 416 18-Watt General Purpose Unit 230-231 20-Watt Economy Modulator 233-235 50-Watt 6L6 Modulator 231-232 100-Watt All Push-Pull Modulator 235 250-Watt High-Gain Class-B Unit 235-236 500-Watt Class-B Modulator 236 Class A 57, 219 Class B Modulator 58-59, 219 Class B Linear R.F. Amplifier 58, 220 Class C 59, 221-223 Amplitude and Power...

Thicknessthousandths Of An Inch

805 frequency-thickness relationships of X-, y- and at-cut plates is negative frequency decreases with an increase in temperature and lies between minus 15 and minus 25 cycles per million per degree C. For example, if through heating the temperature of an X-cut 7-mc. crystal changes from 70 deg. F. to 120 deg. F., the frequency change may be nearly five kilocycles. Should the crystal be followed by a doubler to 14 mc., the frequency change on the higher-frequency band would be twice as great...

Heavy Duty Chokes For Transmitting

For parallel feed in high powered transmitters 20- 40- 80- and 160-meter amateur bands. High equivalent impedance more than 500,000 ohms. Effective from 1,500 to 15,000 kc. with exception of frequencies between 5,300 and 6,400 and between 8,000 and 9,000. Six thin universal pies. Isolantite core. Insulated mounting brackets secured to Isolantite core with short machine screws. Brackets removable and choke mounted with a single machine screw. Ind. 2.5 mh. Dist. cap. less than 1.5 mmf. D.C. res....

Type

Legends have the same significance as in Fig. Vj 17 uiith the addition of DP, diode plates, and SH, shield the shield is the metal envelope of the tube, in all eases connected to pin No. 1. Views are of bottoms of tube bases or sockets. tubes, in which case a new number generally is required to conform to the present numbering system. In still other cases the tube is a new type equipped with an octal base. Tables I-A and IV-A list the G type tubes, giving the equivalents when such exist. There...

Ndbook

F8AA34 Mc to 18 Mc 10.00 FBA 19.5 Mc to 11.4 FBB 11.7 Mc to 7 FBC 7.3 Mc to 4 FBD 4.2 Mc to 2.4 FBE 2.5 Mc to 1.5 FBF 1.5 Mc to 0.9 F8AA34 Mc to 18 Mc 10.00 FBA 19.5 Mc to 11.4 FBB 11.7 Mc to 7 FBC 7.3 Mc to 4 FBD 4.2 Mc to 2.4 FBE 2.5 Mc to 1.5 FBF 1.5 Mc to 0.9 AB-10 10 meter band 12.00 AB-20 20 meter band 10.00 AB-40 40 meter band 10.00 AB-80 80 meter band 10.00 AB-160 160 meter band 10.00 The FB-7 is a seven tube receiver having exceptional sensitivity, selectivity and stability. Ample...

New Varimatch Input Transformers

PA-49 Push pull 45, 59 or 6L6 plates to push pull 845A prime grids. PA-2 _ 4.50 PA-50AX Single 53, 56, 6C5, 6C6 triode. 6A6 to Class B 53, 6A6 or 6E6 grids or single 89 to Class B 89 grids. PA-1 - 3.30 PA-51AX Single 46 or 6L6 to Class B 46 or 59 grids. Single 45, 59. 2A3 or 6L6 to Class B 46 or 59 grids. Single 49 to Class B 49 grids. Single 37. 76. 6C6 or 6C5 triode to Class B 19 or 79 grids. Single 30 to Class B 19 or 79 grids. Single 89 to Class B 19 or 79 grids. Single 2A5, 42, 45 triode...

Planetary Or Vernier Unit

The only dials available in both direct drive and 5 to 1 vernier drive that are identical in appearance. Made of heavy gauge brass, chromium-plated, finished in a circular grain sun-ray satin that will not tarnish even by the seaside. The graduations are die stamped which assures accuracy not to be confused with etched types which are less costly and less accurate . Spring mounted decimal indicators permit readings to one tenth of one division. No. 292 Dia. 4 direct drive dial. List price 2.50...

Utc Varimatch Vm-1

A d CL JoAqsL the NEW UTC VARIMATCH Modulation Transformer will Match ANY Modulator Tubes to ANY RF Load . . . . The Varimatch transformer will not only match PRESENT available modulator tubes, but any tube that may be released at a FUTURE date. All you have to decide is the DC input to your RF stage. Then just pick the VARIMATCH output transformer that will handle the maximum audio power required. These transformers will also match the line impedance output of PA or similar amplifiers direct...

Oneten Receiver

The One-Ten Receiver fulfills the need of the experimenter for an adequate receiver to cover the immense and ever more valuable field between one and ten meters. Designed chiefly for the experimenter, this receiver has been engineered for maximum sensitivity, high signal-to-noise ratio, a wide frequency range, ease of operation and with particular consideration for the characteristics of experimental high frequency transmitters. A four tube circuit is used, composed of one tuned R.F. stage, a...

An Elementary Superregenerative Circuit

Superregenerative Receiver Tube

With grid rectification as shown, the increase in grid current when a carrier signal is applied causes an increase in grid voltage in the negative direction, consequently the average plate current of the grid detector decreases when a signal is applied. Grid detection is generally used in amateur receivers of limited r.f. amplification because grid detectors are capable of greater sensitivity for small signals than plate detectors, using similar tubes. Plate...

Unitycoupled

The result is a broad, rough signal, unpleasant to the ear and illegal under the amateur regulations. To prevent dynamic instability it is essential that the plate supply be the best pure d.c. obtainable and that the grid bias or grid leak be sufficiently high in value. Moreover, too much care cannot be exercised in adjusting the grid excitation. Dynamic instability can be reduced by careful circuit design the use of a High-C plate tank is especially effective. Such a tank circuit is capable of...

Machines For Rent Or Sale

The Instructograph Code Machine is manufactured in two sizes. The Standard, as illustrated above, includes a full set of ten tapes and the Book of Instructions. This machine may be rented at a nominal monthly rate, and the rental paid may be applied on the purchase price, if it is desired to purchase after three months trial, or sooner. The Junior Model, similar in appearance to the standard machine, only smaller and with five tapes and the Book of Instructions, is not rented but may be...