T EVIS i - AmericanRadioHistory.Com

More documents

Recommendations

Info

Fig. 3. The grid -dip meter. Top portion may serve as a wavemster. it is used as the tank circuit of an oscillator. This provides more than adequate range to cover the less than 2:1 frequency range required by the new 470- 890 mc. u.h.f. band. Inductance of the cavity is varied by rotating a brass fin in the cavity field. This fin acts as a shorted turn and represents a convenient way of trimming the inductance of the tuned circuit. The practicability of this device lay in the ability to manufacture the dielectric sleeve with sufficient accuracy. Should the plunger have lateral motion in the dielectric once its position is set, the unit would be susceptible to micro - phonics and backlash, thus proving quite unsatisfactory for use in a u.h.f. tuning element. Production techniques for realizing almost unheard of accuracies have been developed exclusively for this application, making the device commercially feasible at a reasonable cost. Advantages The question now arises as to why this particular arrangement was finally chosen as the ideal u.h.f. tuning element for the new band of frequencies. Most important is (1) that the construction is simple, and the severe close tolerances required by u.h.f. are easily held. Then, (2) there are no moving electrical contacts. This results in a long, noise -free life, with no contact finger or plunger wiper wear. The fact Fig. 5. Diagram of sweep generator. that there are no moving electrical contacts also results in a considerably higher Q tuning element than would otherwise be possible. Extremely high Q's are attainable using this configuration (3) ; Q's of 1000 or more have been achieved. The use of high Q circuits for the tuner element insures low noise figure and high gain. Also, trimming and padding of the unit is easily achieved (4), thus assuring three -point tracking. Rigid construction (5) assures excellent frequency stability. As a matter of fact, the unit lends itself admirably to virtual self -compensation of thermal drift. The completely shielded construction makes the unit independent of its environment (6) since its field is internal; and outside motion, such as hand capacitance, has practically no effect on resonant frequency. This construction also keeps radiation from the tuning element to a minimum. The reasons given above were all considered important in arriving at the choice of a tuning element. There is, however, another very important reason for its choice which is (7) that the Flq. 4. Capacitance tuning of cavity. whole unit lends itself admirably as a generic element for a line of u.h.f. test equipment. The following u.h.f. equipment is required in a well- equipped laboratory working to develop u.h.f. television receivers and associated products: 1. Signal generator 2. Sweep generator 3. Wavemeter 4. Grid -dip meter 5. Composite picture, sound and sync signal generator These instruments have recently been developed by Granco Products Inc. to fill its own growing need for laboratory and production instruments in the development and production of u.h.f. television products. The top unit in Fig. 3 shows the wavemeter design using the tuning element described. A small plug - in coupling loop is brought out at one end of the "cavity" for use as a probe. The signal is rectified by a 1N72 crystal and the detected current read on a compact meter conveniently mounted in the end of the instrument. Provision is also made to plug in a more sensitive meter when required. Because of the high Q of the cavity, this wavemeter is unusually sensitive, and extremely weak signals can be detected with negligible reaction on the circuit under observation. The instrument as presently constituted has a 13" dial scale with accurate individual calibration from 380 to 1000 mc. This unit is particularly useful in the design of any oscillator both as a wavemeter and relative power output meter. It can be used in the latter function by being placed in a fixed position relative to the circuit under test, making the meter reading a function of the power output of the oscillator. By converting the wavemeter into an oscillator, capable of either external or internal amplitude modulation, the versatile grid -dip meter (shown in Fig. 3) was developed. A switch is provided to turn off the oscillator for operation similar to the wavemeter. The addition of the oscillator has greatly extended the instrument's utility. Because of the accurate frequency dial, high output and stable operation, it may be used as a compact u.h.f. signal source for numerous applications - for example, as a marker source when sweeping a television receiver, as a probe for detection of parasitics and in determining the self - resonant frequency of circuit components. Provision is also made for earphones or other types of detection facilities. The power cable to the oscillator has been so designed that it will plug directly into the power connector of the Measurements Corporation's popular megacycle meter, thus extending the range of this instrument from 400 mc. through 1000 mc. A small, compact sweep generator covering the u.h.f. television band, and having a sweep width of approximately ±80 me., is shown in block diagram form in Fig. 5. This instrument uses a resonant cavity circuit mounted so that the cavity rides on a smooth rod, the position of which is controlled by the center frequency knob. As the cavity is moved, a plunger moves in to the cavity to change its frequency. This plunger (Continued on page 30) Fig. 6. Block diagram and waveforms for the picture signal generator. 470 MINUS VN. F SIGNAL TO ego MINUS VHF SIGNAL CENTER FREQUENCY VARIABLE FROM 470 -890 MC. 4MC. K ;gg o I (t R A D I O - E L E C T R O N I C E N G I N E E R I N G APRIL 1953
Make your U H F circuits as simple as V H F designs... Use these two New Sylvania Tubes in tuners and converters tk_ VHF UHF AMP. 6AN4 VHF UHF MIXER 6AN4 TO I F VHF UHF L. O. 6 T 4 Equipment Manufacturers! Simplify design of combination VHF -UHF tuners, UHF converters for TV! Two new Sylvania -developed tubes permit adaptation of conventional amplifier- mixer -local oscillator circuit to the new frequency bands- completely eliminate complicated switching arrangements or stage duplication. Leading Tuner Manufacturers have adopted these types for current tuner production. Short Bulb T -51/2 7 -pin miniature construction Requires no special socketry Designed for use at frequencies up to 1000 mc Double plate and grid leads Uniformity at high frequency means lower cost and better availability THE SYLVANIA 614 is designed for use as a local oscillator at frequencies up to 1000 mc. Used as the companion tube to the 6AN4, it makes possible the design of extremely simple combination tuners and UHF converters. THE SYLVANIA 6AN4 can be used both as an rf amplifier and as a mixer. Its performance in the VHF band is equal to or better than previously existing types of tubes, and in UHF tuners it gives comparable performance to VHF tuners. The 6AN4 is designed for both high gm and high mu. Under representative operating conditions as a Class A amplifier, the transconductance is 10,000 micromhos and the amplification factor is 70. When used as a mixer, the 6AN4 offers the advantages of a conversion gain and of relatively low oscillator drive requirements. Complete technical information on operating characteristics, including performance curves, is included in the manual, "Sylvania's UHF Story." A copy is yours for the asking. Write to: Sylvania Electric Products Inc., Dept. 3R -1003, 1740 Broadway, New York 19, N. Y. SYL\T\ IA x Representative block diagram of combination VHF -UHF tuner using the new Sylvania 6AN4 as rf amplifier and mixer, and the 6T4 as local oscillator. z COMPARATIVE PERFORMANCE OF THE 6AN4 AT VHF AND UHF CONDITIONS Single tube in Channel 13 booster Two tubes in cascade in Channel 13 booster Single tube in open holf -wave tuned amplifier at 450 mc. Single rube in open holf -wowe tuned amplifier at 900 mc. 2.0 1.5 1.0 ó i 0.5 V VHF UHF VOLTAGE GAIN 6AN4 5 11.1 112db 10db Eb /.150 VOLTS Rk- 280 OHMS ? OrJ4,0 . VSWR ,4a G? O 0.5 1.0 1.5 2.0 2.5 OSCILLATOR INJECTION VOLTAGE NOISE FIGURE 9.2 db 8 db 13 db 15 db ...........,... 3.0 3.0 2 Ó 2.0 g zo 1.0;n Curve shows representative relationships between conversion gain and input VSWR of the 6AN4 when used in mixer service, plotted against oscillator injection voltage. RADIO TUBES; TELEVISION PICTURE TUBES: ELECTRONIC PRODUCTS; ELECTRONIC TEST EQUIPMENT: FLUORESCENT IMPS, FIXTURES, SIEN TUBING, WIRING DEVICES; LIGHT BULBS; PNOTOUMPS; TELEVISION SETS APRIL, 1953 RADIO - E L E C T R O N C ENGINEERING 17
Page 1 and 2: T EVIS i N APRIL 1953 IN THIS ISSUE
Page 3 and 4: YOU PRACTICE COMMUNICATIONS with Ki
Page 5 and 6: I NOW...from D.T.I.s MILLION DOLLAR
Page 7 and 8: "I Read You Five." Welcome Words! H
Page 9 and 10: THE ONLY COMPLETE CATALOG FOR EVERY
Page 11 and 12: Get yourself on the beam to the BIG
Page 13 and 14: Look! New small size Adashaft Radio
Page 15 and 16: FETTER RECEPTION EVERY Ol oN 1111.
Page 17 and 18: A LOOK INSIDE PROVES WHY PAY A SERV
Page 19 and 20: TELEVISION RADAR ELECTRONICS RESEAR
Page 21 and 22: BETA RADIATION GAUGING METHODS By G
Page 23 and 24: would have in controlling the proce
Page 25 and 26: is done, the meter on the Microvolt
Page 27 and 28: I voltage regulation', '.'. as well
Page 29 and 30: DECAY CONSTANT IN VIBRATING SYSTEMS
Page 31 and 32: I I (5000), and Curie point* occurr
Page 33: COAXIAL CAVITY TUNING ELEMENT Fig.
Page 37 and 38: (// Capacitors shown 21 /7 times ac
Page 39 and 40: RCA N E E DS E NGI N E E RS who won
Page 41 and 42: O N FREQUENCY CONTROL FOR MILITARY
Page 43 and 44: i Gpoßt i. NOW YOU CAN 4 pvRAVE ti
Page 45 and 46: known as the 5894 -A, because the c
Page 47 and 48: Ticnife "FILTER DESIGN DATA FOR COM
Page 49 and 50: Converter Calibration (Continued fr
Page 51 and 52: For opportunities within your reach
Page 53 and 54: Sweeping the Country! Collins Audio
Page 55 and 56: ULTRA FAN series-Complete VHF -UHF
Page 57 and 58: 1 029 Leonard C. Lane, B.S., M.A. ;
Page 59 and 60: A Transistor of point -contact type
Page 61 and 62: PH I LCO TESTERS Now Yours on NEW S
Page 63 and 64: Mriiffffifff(i ( l ((( THE RADIART
Page 65 and 66: TRAIN FASTER- TRAIN BETTER- TRAIN E
Page 67 and 68: A ROBOT ELECTRONIC TURTLE Closeup v
Page 69 and 70: 7. Solder to the ends of the Fa " s
Page 71 and 72: THE semi -automatic or "bug" key is
Page 73 and 74: ' even a small wooden box may be us
Page 75 and 76: Fig. 1. The compact, versatile mobi
Page 77 and 78: access to a surplus TU -10-B tuning
Page 79 and 80: CHANNELS Pertinent frequencies and
Page 81 and 82: quency definition probably wasn't n
Page 83 and 84: conicals are usually stacked two or
Page 85 and 86:
THE U T SPEAKER ENCLOSURE Design de
Page 87 and 88:
a drop of 6 db -per- octave above 5
Page 89 and 90:
Fig. 1. (Left) Front panel view of
Page 91 and 92:
Fig. 3. Bottom view of the 30-watt
Page 93 and 94:
A LOWR[SISTA NCE OHMMETER _ By J. P
Page 95 and 96:
By HAROLD HARRIS Vice -President, E
Page 97 and 98:
erticle, the results are not too fa
Page 99 and 100:
Sete/t SHORT -WAVE Compiled by KENN
Page 101 and 102:
dual triodes with the necessary int
Page 103 and 104:
You, ecutiAtea a &LtAufoP4Lo ctZ& b
Page 105 and 106:
The data that Launched Thousands of
Page 107 and 108:
Te MANUALS SHOW YOU HOW. Here is vi
Page 109 and 110:
NEW WIDE BAND VERTICAL AMPLIFIE Dir
Page 111 and 112:
Indicates frequency of energized ci
Page 113 and 114:
NAL TRACER KIT OCATOR AND WATTMETER
Page 115 and 116:
Mod.loied or nwdc kited RF output.
Page 117 and 118:
SUPERHETERODYNE High gain dual iron
Page 119 and 120:
H. D. Suesholtz, General Manager, T
Page 121 and 122:
It will count events occurring eith
Page 123 and 124:
1 EE101so Mc, MAIL YOUR ORDER TODAY
Page 125 and 126:
Which Yo Want? Guet your FCC Ticket
Page 127 and 128:
Code Practice Oscillator (Continued
Page 129 and 130:
. =Ms or ...eel, u ' tically. topla
Page 131 and 132:
1 II{ Phono Equalizers (Continued f
Page 133 and 134:
1 BA" None None Top Top THE BEST IN
Page 135 and 136:
What's New in Rac io (Continued fro
Page 137 and 138:
59 .n 89 60 .89 54.95 . .69 . 1.59
Page 139 and 140:
a noted 0630 with news, strong leve
Page 141 and 142:
Clearly ' lia) Radio France -Asie,
Page 143 and 144:
le in any variable power supply, no
Page 145 and 146:
. SI9.95 \I e \ With 1 \I I.IB . 1.
Page 147 and 148:
denser (Admiral par number 65B6 -26
Page 149 and 150:
nllent 95 D.e.198 e B d. Adjust the
Page 151 and 152:
Antenna Measurements (Continued fro
Page 153 and 154:
impedance" and is an import ant con
Page 155 and 156:
- 1 Junius Heard with news 0730 on
Page 157 and 158:
allo is French session 0630 on 15.1
Page 159 and 160:
v IlIllIllIlli IllIllIllIll
Page 161 and 162:
NEW TV PRODUCTS On The Market "TELO
Page 163 and 164:
entire u.h.f. band. A sin ;le switc
Page 165 and 166:
layout charts and floor arrangement
Page 167 and 168:
Fringe Antennas (Continued from pag
Page 169 and 170:
a theater TV in the frequency spect
Page 171 and 172:
Receiver Change s (Continued from p
Page 173 and 174:
:nrh BF "BASIC ELECTRONIC TEST INST
Page 175 and 176:
S0.62 f tical and easily- understoo
Page 177 and 178:
B2 IT'S TERRIFIC! Fig. 3. Circuit t
Page 179 and 180:
h' SGP1 7867 Within the Indust.), (
Page 181 and 182:
VARIABLE PULSE LIGHT SOURCE HUNGER
Page 183 and 184:
completely new system of closed con
Page 185 and 186:
p ice businessman sells time, know
Page 187 and 188:
It is apparent from the information
Page 189 and 190:
1 -Improving Ir71 vision Technician
Page 191 and 192:
i 2 Rate 50c per word. Minimum 10 w
Page 193 and 194:
Assembling the components of Raythe
show all

T EVIS i - AmericanRadioHistory.Com

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?