COMPLEX amplifying circuits for the magnification of radio ~ndtone frequency currents require an amplifying Vacuum Tube ofrigid operating characteristics. There is an increasing demand

among radio ex,perimenters for a vacuum tube amplifier which willmagnify the telephone currents in a radio receiving set and which can be

shifted from one socket to another in a cascade outfit without loss of signal audibility.Moreover, the amplifier must be free from the tube "noises" accompanying the use of im-properly designpd vacuum tubes.

RADIOTRON U. V. 201, the second of the new series of Vacuum Tubes designedby the engineers of the Research Laboratory of the General Electric Company for theRadio Corporation, possesses the qualifications outlined above and it should be a part ofevery experimental radio receiving station. U. V. 201 may be used as a detector, or as atone frequency or radio frequency amplifier.

In cascade radio frequency amplifying circuits, U. V. 201 can be adjusted to mag.nify without distortion. The use of such ,circuits is on the increase in amateur stations,

I ~ :V:JI, - .- particillirlJb.~~.lQJI&.Jij§tayse ('~ommunica!ionjs" desired. on short wave lengths ..(~meters or less),

As a detector the best results are secured from Radiotron U. V. 2(J1with a grid con-denser of approximately .0001 mfd. capacity 'and with a shunt GRID LEAK of lh to 2megohms, according to the type of circuit employed.

The norm~l plate voltage of Radiotron U. V. 201 is 40 volts, although increasingamplifications can he obtained at plate voltages up to 100. At 40 volts on the plate, theamplification constant varies from 6.5 to 8; at 100 volts on the plate, from 8 to 10. Theoutput impedance varies from 15,000ohms to 25,000ohms at 40 volts on the plate, and from10,000 to 15,000with 100 volts on the plate.

The nor~al fila~ent curr~nt for RADIOTRON U. V. 201 is approximately 1 am.pere. The filament is designed for connection to the terminals of a 6-volt storage batterywith a standard filaPlent rheostat in series.

To obtain maximum amplification with U~ V. 201 means should be suppliedfor placing negative potentials on the grid, although' good amplification may be securedwithout any spe~ial provision for such potentials. The requisite negative grid potentialfor the use of U. V. 201 in amplification circuits can be secured by connecting a standard"C" battery of two or three volts in the grid circuit, shunted by a 200 to 400 ohm poten-tiometer, or by placing a 2 ohm resistance in series with the negative terminal of thefilament and connecting the "low" potential" terminal of the tuner secondary to includethis resistance in the grid circuit. The latter method usually provides the requisite gridpotential results, but the proper value for maximum amplification is generally best foundby trial and experiment, with a variable source of e.m.f. supplied locally.

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RADIO CORPORATION of AMERICARADIOTRON U. V. 201

A NEW AMPLIFIER, OF THE PLIOTRON TYPEFOR

AMATEUR AND EXPERIMENTAL WIRELESS STATIONS

IMPORTANT FACTS CONCERNING RADIOTRON U. V. 201The Radio Corporation's gas content detector and amplifier tube, RADIOTRON U.

V. 200, is in itself an excellent tone frequency amplifier, hut it does not give the "power"amplifications obtainable from the Corporation's SPECIAL AMPLIFIER TUBE RADIO·TRON U. V. 201. 'Thus, for devices requirinl! a considerable amount of energy for their

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Figure 3 indicates a complex detection and amplification circuit in whichU. V. 201will be found desirable. This circuit is made up first of three stages of radio frequencyamplification, followed by one detector tube and two stages of tone frequency amplification.

In the radio frequency group, P·I, C·I constitute the tuned primaries of rad io fre·quency transformcrs, and P-2, C-2, the tuned secondaries, through which amplified radiofrequency currents are impressed upon the grids of successive tubes. Negative grid poten.tials for distortionless amplification are obtained by the use of a "C" battery of 1 to 10

----II-r--AJ_-O.}.t-s,---sh-1Hl-t~d_h_y__a-su i-t~'1-h-lG--potcl'l.-t-iolll.etel'. Th e ra d j o-.ll:eq.uen.cy CDrrents~t h e_ g!:i fI 1_'_circuit are by-passed around the potentiometer by a shunt condenser. Y;

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The grjd condenser C-3 in series with the grid of the fourth tuhe (assisted by theGRID LEAK R-2) rectifies ,the amplified incoming radio frequency currents, and the out.put CUlTents of the fourth or detector tube are further amplified by two stages of tonefrequency amplification.

RADIo,TRo,N U. V. 201 should be used throughout the circuit of Figure 3.

If RADIo,TRON U. V. 201 is used throughout the circuit of Figure 2, the platecircuits of all three tubes may be energized at voltages from 40 to 100 volts. If RADIo,-TRo,N U. V. 200 is used as the detector, the tap 1'·2 should be set at approximately 13volts. The "A" battery potentiometer R-3 may he dispensed with when RADIOTRo,N U.V. 201 is used as a detector as well as an amplifier, as mentioned above.

Tone frequency amplifying transformers are indicated at pol and P-2. Separatefilament rheostats are shown for each tube, but if U. V. 201 is used for detection and foramplification, many amateurs will operate the filaments of all tuhes through a single fila-ment rheostat of the proper current carrying capacity.

r-ROdliJ rre'luenc!I Amplifier-

UV201 UV201 UV201~p, 1', ~ ,.---; P, P..--..,--

Fig. 3

-----I

CIRCUIT FOR RADIO AND TONE FREQUENCYAMPLIFICATION AND DETECTION

Fig. 4

U5Ji79'!?od/otron' U V 201 throughout the ClrCUI!

RESISTANCE-COUPLED AMPLIFIER CIRCUITFigure 4 illustrates a resistance.coupled amplification circuit in which there are

three stages of radio frequency amplification, the fourth tube being used as a detector. Thetone frequency output of the detector tube is in turn amplified by two additional tubesin cascade.

For radio frequency amplification R-I represents a coupling resistance of lh megohm(The Radio Corporation's standard grid leak resistance may he used for this purpose.)R-2 indicates a GRID LEAK of approximately 2 megohms. P·I and P-2 are suitable inter-valve tone frequency transformers. A is a 6-volt storage battery of suitable current output,and B a plate battery providing from 40 to 100 volts for the plate. If a single filament

r-=-- ~ .... .. 'W!f<

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rheostat such as R-4 is employed to control the filament current of all the tubes, the pre-caution should be taken to secure a rheostat of suitable current carrying capacity, allow-ing approximately 1 ampere for each tube.

There are numerous other circuits in which RADIOTRON U. V. 201 may be usedwith inarked results.

Standard Vacuum Tuhe Socket

Standard Grid 1,e(14;

1nter-vaive Traniformer

NOTE:-The Rndio Corl)Or:ltioll lias in JlUlllllfnctlll'e 11 IlC'"Alnl)Hf,..·ing; 'l':t'unsforlue1.' designed sllecifically to fit the ontl)1ltcircuit of RA.DIOTRON U. V. 201. The trunsf01'JUer incOrl)01'ntes('ertnin ltOl'e-1 ft·:ltures of cons'trnctiou and J;l;'h'es :111ovel'-nll t"fli-('ieu('~T not )·(>ot :llllu'onc)u"tl by uny otller tYlle. It is n. devi{'t" ofsu)el'it)]; u'ol'l{uu,"sltil) ;Iud it is lJot"to lle confounded ""jtb illt("1· ...,'ulve tl'ulllOlfnl'lut"rs dt"sigll{"(l only to l)t~ sold :It a ellenl} llrice. De-liYt"1.·)~ dute "'ill I)e nllllOll11Ced l:tt(~l·.

RADIOTRON U. V. 201, in addition to its usefulnessto the experimental wireless station, is also recommendedfor experimental investigations in the laboratories of HighSchools, Colleges, Universities and for general instructionalpurposes.

ACCESSORIESThe Radio Corporation has in process of manufacture

a number of ACCESSORIES pertaining to the practicaluse of Vacuum Tubes. These include special "A" batterypotentiOineter~, filament rheostats, new forms of vacuumtube sockets, grid condensers of novel design, and manyother devices which for. obvious reasons cannot be an-nounced at this time.

High grade workmanship characterizes the accessories.They are built for those who want the best at moderatecost.

New Amplifying Transformers for tubes are in manu-facture. These incorporate unusual features of design andgive amplifications markedly above those obtained fromexisting types. We~11ave~sofi1esurprises ill store-for-Ex-perimenters. .

LIST PRICESRADIOTRON u. V. 201, Pliotron amplifier .RADIOTRON U. V. 200, gas content dectectorR. C. STANDARD VACUUM TUBE SOCKET .R. C. STANDARD GRID LEAKS, 30 values (from !'2 10 6megohms) each mounted 1.25

R. C. GRID LEAK UNIT only .75R. C. GRID LEAK MOUNTING . . . ., .50TONE.FREQUENCYINTERVALVE TRANSFORMER - 7.50

Watch current Radio magazines and Electrical Mer-chandise papers for future announcements concerning newdevelopments.

$6.505.001.50

SALES DIVISION-COMMERCIAL DEPARTMENT

of AMERICARADIO CORPORATION233 Broadway New York City

PURCHASERS OF THE RADIO CORPORATION'S AMATEUR AND EXPERI-MENTAL DEVICES ARE REQUESTED TO PLACE THEIR ORDERS THROUGHTHEIR LOCAL DEALERS. IN THE EVENT THAT THERE IS NO DEALER IN YOURLOCALITY, WE WILL PUT YOU IN TOUCH WITH THE NEAREST ONE.

If you have not already seen our special bulletin for Radiotron U. V. 200, the gascontent detector, ask your Dealer for it or write us direct.

ON SALE BY~

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