US1294983A - Station for wireless telegraphy and telephony. - Google Patents

Description

G. vow Mice) &'-A. MEISSNER. STATION F08 WIRkLESS TELEGRAPHY AND TELEPHONY. APPLICATION FILED DEC. 27. 9]2. NENEWED JUNE II, 1918.

Patented Feb. 18, 1919.

6 $HEETS-SHEET I.

G. VON ARGO 31 A. MEISSNER.

STATION FOR WIRELESS TEL EGRAPHY AND TELEPHONY. APPLICATION FILED use. 27. 1912. RENEWED mm: 11, may

Patented Feb. 18, 1919.

6 SHEETS-SHEET 2.

G. vow ARGO & A. MElSSNER.

STATION FOR WIRELESS TELEGRAPH! AND TELEPHONY. APPLICATION FILED 050.27, :912. RENEWED JUNE 11. 191B.

lfi l fiw Patented FehlS, 1919..

6 SHEETS-SHEEI 3.

G: VON ARGO & A. MEISSNER'. STATION FOR WIRELESS TELEGRAPHY AND TELEPHONY. APPLICATION FILED DEC. 2?, 1.9!2. RENEWED JUNE I1; 1913- Patented m. 18-, 1 919,

((3 SHEETS-SHEET 4.

G. VON ARGO & A. MEISSNER.

STATION FOR WIRELESS TELEGHAPHY AND TELEPHONY. APPLICATIGN FILED DEC. 27. 1912. RENEWED JUNE 11, I918.

Patented Feb. 18, 1919.

6 SHEETS-SHEET 5- 7 fag, W;

G. VON ARGO & A. MEISSNER. STATION FOR WIRELESSIELEGRAPHY AND TELEPHONY.

APPLICATION FILED DEC. 27, I912- RENEWED JUNE 11. I918. 1 94,5383, Patented Feb. 18, 1919.

6 SHEETS-SHEET 6.

GEORG VON ARGO AND ALEXANDER MEISSNER, 0F BERLIN, GERMANY, ASSIGNORS T0 GESELLSCT Flll'R DRAHTLOSE TELEGRAPHIE M. B. TL, 015 BERLIN, GERMANY, A

CORPORATION OF GERMANY.

STATION FOR WIRELESS TELEGRAPHY AND TELEPHONY.

Specification of Letters Patent.

Patented Feb. 1%, 119..

Application filed December 27, 1912, Serial No. 738,864. Renewed June 11, 1918. Serial No. 239,496.

have invented certain new and useful Im-' provements in Stations for Wireless Telegraphy and'Telephony, of which the following is a specification.

The object of the present invention is a transmitting station for wireless telegraphy and telephony, in which the high frequency current instead of being produced by spark discharges of arcs, is generated by machines. The former attempts to generate high frequency currents in machines have failed, so far as applicants are aware, because it 15 not possible to produce with it appreciable amounts of energy in the high frequency machine. So far as experimenters have recently succeeded in constructing high frequency generators for appreciable. amounts of energy, such machines owing to their peculiar [construction have proven to bet exceedingly expensive. Aside from this such generators have shown a number of technical defects, above all the defect that a change of wave length within wide limits, such as is required for transmittin stations in most instances, can be obtaine only by controlling the revolution number of such generators within very wide limits. Thus it becomes necessary to operate such a generator very uneconomically in order to satisfy the requirement ofa wide range of wave lengths.

The means for producing high frequency oscillations directly as described in the.

present application, overcome all these di sadvantages and it becomes POSSIble to obtam as well a very high technical efi iciency as also a very economical arrangement, and also thevrange of waves at the d1sposal of the operator is rendered sufficiently large without materially varying the speed of the generator.

' The invention is based'on an arrangement for increasing the frequency in which in stationary frequency changers the frequency is doubled by means of an auxiliary mag-' netization and in which also by placing such apparatus in cascade arrangement relatively to each other a repeated doubling of the frequency may be obtained.

Such frequency changers in themselves are known in the art and are illustrated and described for instance in the British Patent #11526 of 1911 to Oliver Tmray.

Experiments have shown that with such frequency changers, when the proper wiring arrangement is used, also an increase to the value of any desired multiple of the funda mental frequency may be obtained in one or only every few sets of frequency changers. If a generator is used the fundamental frequency of which has already the value of from 5000 to 15,000 per second, the efficiency of the entire arrangement becomes very high and such transmitting stations can be built at a considerably smaller cost than a generator which produces the required frequency directly.

The invention therefore resides as well in the particular form of the frequency changers as also in the combination of a number of such apparatus by which the necessary high frequencies are produced by only a few sets of changers and by which also the adjustment of a large number of frequency steps is permitted. In using these above mentioned means all alternating current circuits must be sharply tuned by means of inductance and capacity to the periodicities produced in these circuits, in order that the amplitude of the currents is properly increased, and in order that losses may be avoided.

In the accompanying drawings which illustrate our invention, Figure 1 shows the arrangement of a station in its entirety;

Figs. 2 and 3 show details of the switch levers used in the switches;

Fig. 4: shows the switches arranged in a manner to connect the primary windings of the two frequency changers C, D in parallel to double the machine frequency;

Fig. 5 shows the primary windings of the two frequency changers C, 11) connected in series; A

Fig. 6 shows an arrangement by which the frequency, doubled in one changer set may be redoubled in the same set:

Fig. 7 shows an arrangen'icnt for producing any desired higher uneven frequency in the same set by means of suitably arranged alternating current resistances;

Figs. 8 and 9 show an arrangement for further increasing the uneven frequencies obtained by the means shown in Fig. 7;

Fig. 10 shows an arrangement for obtaining double the frequency in the secondary by auto-transformation at the primary of the same set, both primaries being in parallel to the generator;

Fig. 11 shows an arrangement for the same purpose as that shown in Fig. 10, both primaries in the present case being in series with the generator;

Figs. 12 and 13 show arrangements in which the primary windings of the frequency changer set-also carry the auxiliary magnetizing direct current.

Referring first to Fig. 1, A represents an alternating current generator whose frequency is increased by means of stationary frequency changers C, D and C, D, in such manner that the antenna J receives high frequencies of the periodicity desired. Generator A is a so-called high frequency generator which, however, compared with the antenna frequency still produces currents of only a con'iparatively low frequency. Preferably the generator should have a fundamental frequency of at least 5000 cycles per second. It has been proven in practice that generators of such frequencies can be built at still comparatively low cost. The stationary frequency changers such as for instance C, D consist of one or sevefiil closed iron yokes, on which high frequency windings 2, 3 and 5, 6 respectively and 21, 27 and 24, 25 respectively and also the direct current windings 19, 20 and 12, 13 respectively are disposed. The electrical effect of such yoke is Well known in-the art and explained in aforesaid patent, so that their theory need not be further explained in the present application It may be stated, however, that while the lines of force produced by an alternating current supplied to coil 2, 3, in one direction will find the iron of the yoke already saturated by the lines of force produced by the direct current coil 19, 20, so that the alternating current in coil 2, 3 only has to overcome the inductance of this la tter coil, the iron is demagnetized on the other hand when the alternating current passes through coil 2. 3 in the other direction, so that a very high counter-electromotive force is set up in this coil.

If, now, the coils of two of such yoke-s are properly connected with their alternating current windings. it is possible to receive at r th terminals of the secondary coils an alternating current of double the fundamental frequency if current of such fundamental frequency is supplied to the primary coils. This arrangement is known in itself for the case -where the alternating current coils which receive the primary current are arranged in series with the generator.

In the following a description of the modification shown in Figs. to 13 is giren with reference to the individual figures, though all these modifications are contained in Fig. 1 showing the general arrangement of a station as above mentioned. In this station through the proper setting of the switches B, F, G, H, M, P and others which may be mentioned hereinafter, the several modified arrangements shown in Figs. 4 to 13 may be produced. On account of Fig. 1

' being capable of such a large number of different combinations by arranging the several switches shown therein, the switch arms of these switches for which for instance examples are illustrated in Figs. 2 and 3 have only been dotted into the switches in l 1g. 1, and their position as shown in that figure i.- not meant to indicate a certain particular circuit arrangement, but merely means to show mechanically. their place in the switch. In the remaining "Figs. i to 13, on the other hand, the switch arms are shown in their proper places for the particular arrangement illustrated by the particular figure. To reproduce the arrangement of any of the Figs. -11 to 13 in Fig. 1, the switch arms in the latter figure only need be set as indicated in the special arrangement which it is desired to produce.

A convenient form of connecting a set of frequency changers is shown in Fig. 4. In this figure the primary windings 2, 3 respectively 5, G of the two changers C, D are supplied in parallel from the high frequency generator A. For this purpose the double pole switch B whose contact arms are constructed as shown in Fig. 3 is set so that its pivotal contacts which are connected with the generator are also connected with -ontact points 1 and 4, whereby through the angular extension of one of the arms also a contact is made between points 4 and 8. In this position of the arms the following circuits are closed from the generator: over 1234 through the primary high frequency coil of changer G and simultaneously by way of l256-781 through the corresponding winding of changer B. The auxiliary magnetizing current is supplied by battery E and supplied to windings 19, 20 respectively 12, 13 by the switch F. The latter connects its pivotal contacts 17, 18 which in turn are connected with the two poles of the battery with the contacts 9 and 14. The direction of current in the auxiliary windings may be rema tose versed b means of chan e-over switch G, so that the magnetizing e ect necessary for the operation of these coils in a frequency changer is obtained for the particular wiring arrangement. In the case of Fig. 4, the direction 12, 13 in which the direct current flows through the coil of transformer D, must correspond with the direction 19, 20 in the corresponding coil of changer C. There fore in Fig. 4 the connections of change-over switch G are shown in full lines, whereas the other possible connection of this switch not used in that figure is shown in dotted lines. In the secondary windings 21, 27; 24, 25 of the two changers alternating current potentials are then obtained which by proper connection of the windings, for in stance by connecting the windings against each other, will result in a potential of double the frequency. By means of switch P these secondary windings may be connected in parallel or in series as desired. In Fig. 4 for instance, the series connection is shown so that for the secondary coil double the frequency exists at the contacts 22, 23 of the switch P; the latter has two pairs of contactarms which are pivoted at the common points 29, 30. If these pairs of arms are set as shown in Fig. 4 the secondary terminals of changers U, D are connected over the tuning elements '0, N

with contacts 33, 37 of switch M. This lat -ter switch is likewise provided with two pairs of contact arms through which when adjusted as shown in Fig. 4 the secondary currents are supplied to antenna J.

The arrangement described above renders possible a doubling of the machine frequency by means of the one set C, D. The connecting in arallel of the primary windings of these 0 angers has the advantage over the known series connection that the efficiency is considerably higher in the former. The series connection by the way may be brought about by arranging snitch B as shown in Fig. 5, in which the generator current flows from 4 over 32-5-6 back till over 7, 8.

If it isdesired to obtain in the antenna a higher frequency than double the machine frequency, this may be accomplished by arranging several sets C, D-C, D, etc, each in accordance with Figs. 4 ,or 5, and then by arranging these sets in cascades so that by the first set a doubling, by the second a uadrupling and by the third eight times t e frequency is obtained and so on. If, in such case the frequency of the generator A is for instance 10,000 per second, three sets connected as above described would produce a frequency of 80,000 per second in the antenna. While this increase in frequency as described is perfectly feasible, still fre quencies above 80,000 can now only be obtained according to the arrangement describedbefore, by further doubling the frequency by an additional set to obtain a fre quency of 160,000.

Now, we havefound that by suitably connecting the circuits containing the higher frequencies, it is also possible to obtain the higher frequencies, such for instance 4 times, 8 times, etc., the fundamental frequency by a smaller number of sets, and in fact only by one single set. The means by which this is obtained consists in a connection of the secondary windings with the primary wind ings in such manner that the frequency which is first doubled in this set is redoubled therein, so that 4 times the fundamental frequency results. Such an arrangement is shown in Fig. 6. By setting one pair of the switch arms of switch I? onto contacts 40, 42 and by setting onepair of the switch arms of switch M onto contacts 47, 48, the above mentioned effect can be obtained. In this arrangement it is assumed at the same timethat the primary windings of the two changes C, D are arranged in parallel by means of switch B in the same manner as shown in Fig. 4, and further that by means of switch F, the direct current windings of the changers are likewise connected in parallel, and lastly. that the other switch arms of switch P together with the proper adjustment of changeover switch H are set so that also the secondary windings of the changer are connected in parallel. The secondary currents of double the frequency which are received at the contacts 29, 30 of switch I are conducted back into the primary windings of changers C, D. The circuit connection to this is completed over contact 40 of switch P, point 41 of the line and terminal 2 of the primary of changer C. and on the other hand from pivotal point 29 of switch P contact 42, points 43, 44, tuning means K, L 45, 6. Aside from this a connection is made of this circuit with the contact points 47, 48 of switch ll/lL, In this manner, the frequency is multiplied several times in the same changer set, whereby the parallel ill:

branches K, L are tuned to double, 4 times i and 8 times the frequency, according to how many times the frequency is to be multiplied. This redoubling of the frequency in one and the same changer set may also be accomplished in case the primary windings are connected in series. ,By this latter connecmental frequenc of the machine may be brought to doub e, 4 times, 8 times its value by comparatively few changers. During the experiments for obtaining increases in frequency by means of frequency changers, connections have been found by means of which higher frequencies of any value, that is to say, twice, three times, four times, five times and so on, the fundamental frequency can be obtained by means of only one set.

We have found that if one or several alternating current resistances are arranged in an oscillating circuit such as described here inbefore, such resistances produce a distortion of the curve of the current which flows in the circuit and we have found that from this circuit higher frequencies can be, so to say, filtered out. In order to do this it is only necessary to connect an oscillation circuit which is tuned to the higher frequency either conductivcly, inductively or by a caacity with the alternating current circuit. S uch an arrangement can be produced in the diagram shown in Fig. l by throwing one switch-arm pair of switch P onto contacts 50, 52, and by throwing one of the switch arm pairs of switch M onto the contacts 47, 49. This particular arrangement is shown clearly in Fig. 7. The primary windings of the changers O, D are connected in series and receive current from the generator A, as described above (not shown in Fig. 7). The auxiliary magnetizing iwindings are likewise arranged as described above. When the switch P is set as just described the secondary windings are open so that they will have no efiect.

On the other hand, by the primary windings the above mentioned distortion of the current curveis produced in the primary circuit formed by these windings and by the generator. The current of the higher frequency is produced by the conductive connection of a circuit containing the tuning means 74, 75 to the primary coils at the points 3 and 6. .By means of this'circuit all the higher frequencies may be' derived from the primary circuit, in particular three times, five times and the further uneven frequencies are easily obtainable. For instance, if the circuit containing the tuning means 74, 75 is tuned to three times the fundamental machine frequency the transmission of energy takes place at a good efficiency. If, at the same time, a second circuit which leads from the tuning means K, L over switch M to the antenna, is for instance tuned to nine times the fundamental frequency, a particularly strong current of nine times the fundamental frequency is obtained thereby.

We have now found that the uneven frequencies obtainable by this arrangement in the circuit which contains an alternating current coil such as the primary coilsof the changer, can be still further increased, if a current generated in the secondary coil and having double the frequency is brought into effect in an auxiliary closed circuit tuned to that frequency. This is shown in detail in Fig. 8. This figure otherwise agrees with Fig. 7 except that the switch arm pair of switch P is thrown onto contacts 31, 32. By such connection the auxiliary circuit which contains tuning ,means 76, 77 is connected with the secondary windings of transformer C, D.

Another wiring arrangement by which likewise all the uneven higher frequencies may be produced by means of a circuit conductively connected to the primary winding at 3 and 6 and tuned to the higher frequency, can be obtained by throwing the arms of switch P onto contacts 50, 51, by which the secondary windings are connected again with the primary windings. This is shown in Fig. 9.

It will be seen that by the last mentioned arrangements illustrated in Figs. 7, 8 and 9, all uneven multiples of the fundamental frequency may be produced by means of one frequency changer consisting broadly speaking of the two elements C, D. If, now in connection with the modifications shown in Figs. 7, 8 and 9, the modifications shown in Figs. 4, 5 and 6 are used, double, four times, eight times and sixteen times the fundamental frequency may be obtained by means. of only one set.

In order now to produce those frequencies not yet obtained in the combinations previously described, two or at most three of the above mentioned sets may be connected in series, and in each of these sets one of the connections previously described may be made. The series connection of the set C, D with the set C, D shown in Fig. 1, can be obtained by throwing the switch arm pair of switch M which, for the purpose of connection with the antenna stood formerly on the contacts 39, 35, onto contacts 64, 65. With these contacts the points 66, 67 of the switch B of the second set are connected which points correspond with the generator contacts 1, 8 in switch B. The currents derived from this set C, D at 68, 69 are returned to the contacts 70, 71 and are then connected with the antenna J by way of 72, 73 and 39, 35. If for instance in this connection of the two sets the first set C, D is within itself connected according to Fig. 4, double the frequency is produced by it at the terminals 34, 38 of switch M. If, at the same time, the second set is for instance connected within itself according to Fig. 7, this set produces three times the frequency supplied to it by the first set if the tuning means K, L are correspondingly adjusted. The antenna-receives in this case from the second set six times the fundamental generator frequency. Ten times the machine frequency could be obtained for instance by connecting the coils of the first set C, D, according to Fig. 4 and those of the second set C, D, according to Fig. 8 and by regulating in the second set the tuning means K, L so that at the points 3, 6, five times the frequency supplied to this set appears. Since by the first set a doubling of the frequency takes place, ten times the machine frequency is obtained at the terminals of the second set. It is apparent from this example without further discussion that thus every desired frequency may be obtained merely by changing the connection'in the general arrangement shown in Fig. 1, according to the difierent forms represented in the figuresjjust described, without thereby varying the speed of the generator. If it now should be desired to obtain frequencies, whose values are between the steps obtainable by the means described above, a comparatively small variation of the generator speed is sufficient for this purpose. Since in the practical use for radio telegraphy the frequencies mostly used represent a simple multiple of the machine frequency, for instance six or more times this fundamental frequency, it is usually sufiicient, in order to bridge the range of waves between two frequency steps, obtainable by changing the wiring arrangement, to vary the generator speepli only within ten per cent. of its normal s cc Tn most of the modifications described above the arrangement may be further simplified by deriving the secondary potentials of double the frequency from the primary coils by auto-transformation instead of using separate secondary coils. For instance if the primary windings are arranged in parallel to the generator the secondary potential of double the frequency may be obtained from a circuit 349p0int of consumption-4C7- 46-45-43 (see Fig. 1). This arrangement is also illustrated separately in Fig. 10.

If, on the other hand, the generator and the primary windings are arranged in series the circuit carrying current of double the frequency runs from 8 over 49-point of consumption4c7-46-61 to 5; and from 6 over 45-62-6349point of consumption-4746-61 to 5. This latter modification is separately illustrated in Fig. 11. If necessary a special switch may be arranged between the points 46 and 45 in Fig. 1 by which this connection may be interrupted (not shown in the figure).

The entire arrangement may be still further simplified by using the primary or secondary Windings'of the changer coils simultaneously for conducting the auxiliary magnetizing direct current through them. If it is desired to send the direct current through the secondary windings the switch F is thrown onto contacts 53. 54 (Fig. .1), so that the current can flow to the pivotal points 29, 30 of switch P over which it then can flow to the secondary windings of changer set C, D. In case the primary windings are used for also carrying the magnetizing direct current these primary windings must be connected in parallel to the direct current source in case they are connected in series to the alternating current generator. while when they are connected in parallel to the alternating current generator they must be in series with the direct current source, because the direct current magnetization in one changer should oppose the magnetization of the alternating current while dur ing the same half period of the primary current the direct current magnetization should support the alternating current magnetization in the other changer. These last two cases are separately illustrated in Figs. 12, 13 respectively. Thus in Fig. 12 in which the primary coils are arranged in parallel to the alternating current generator the circuit for the direct current is as follows: 55-56-7652-35758. On the other hand, in case the alternating current generator and the primary windings are-in series as shown in Fig. 13, the-circuit for the magnetizing direct current has two branches, to wit: 59-60-5-6-7-56-55 and 5960235758. In this position ofswitch F the two contacts 55-58 are directly connected by means of the lateral extension of the left hand switch arm which is pivoted at 18.

By supplying the secondary potentials, produced by auto-transformation in the prirnary windings, to the point of consumption in accordance with the arrangement shown in Figs. 10 and 11 and by using simultaneously the primary winding to also carry the auxiliary magnetizing direct current according to Figs. 12 or 13, each individual changer element C, D operates only with one winding.

Since stationary frequency changers, as described in the foregoing, have in general the property of preventing the return of the secondary energy into the primary oscillation circuit, it is possible to obtain also a frequency characterized by beats, by using a somewhat de-tuned antenna, so that the natural periodicity of the antenna interferes with the impressed periodicity. This beat frequency may be used for producing musical tones, whereby the pitch of the tone is determined either by the extent of the dctuning of the antenna by its own tuning means, or by varying the fundamental machine frequency.

We claim 1. Transmitting station for radio telegraphy and telephony having an antenna, an alternating current generator for producing a desired fundamental frequency, and a suitable number of frequency changers disposed between the generator and the antenna, suitable circuits connecting said changers to multiply the fundamental frequency of said generator, and tuning means in said circuits for tuning the latter to the frequencies of the currents passing through said circuits, and switches for varying the circuit connec tion between said changers to vary the multiple of the fundamental generator frequency produced by said changers.

2. Transmitting station for radio telegraphy and telephony having means for producing current of a desired fundamental frequency, means for multiplying the fundamental frequency in steps, comprising for each step a frequency changer and suitable circuit connection therewith, each changer having primary and secondary coils, the primary coils of each changer being in parallel circuit connection with the circuits carrying the coils of the resulting frequency of the preceding step.

3. Transmitting station for radio telegraphy and telephony having an antenna, an alternating current generator and a suitable number of frequency changers having primary and secondary coils and being disposed between the generator and the antenna, suitable circuits connecting said chan ers to double the fundamental generator requency, the secondary coils, carrying the current of double the primary coil frequency, being conductively connected with the primary coils to again double the fre quency obtained in the secondary coils, and tuning means in the circuit connections between said primary and secondary coils for tuning said circuits to the frequencies cf the currents carried by said circuits.

4. Transmitting station for radio telegraphy and telephony comprising means for producing currents of a desired fundamental frequency, a suitable number of frequency changers and a primary circuit for connecting same with said producing means, an oscillation circuit adapted to conduct currents of the desired resulting frequency and being operatively connected with said primary circuit, said oscillation circuit having means for tuning it to a frequency higher than that of the primary circuit to permit generation of currents in said oscillation circuit of any desired multiple of the fundamental frequency according to the adjustment of said tuning means.

5. Transmitting station for radio telegraphy and telephony comprising means for producing current of a desired fundamental frequency, a suitable number of frequency changers each having primary and second ary coils and a primary circuit for connecting said primary coils with said producing means, an oscillation circuit operatively connected with said primary circuit, said oscillation circuit having means for tuning it to a frequency higher than that of the primary circuit to permit generation of currents in said oscillation circuit of any desired multiple of the fundamental frequency according to the adjustment of said tuning means, the secondary coils of said frequency changers being arranged in series in a closed circuit, and tuning means for tuning the closed circuit to double the frequency of the primary circuit to increase the amplitude of currents of an uneven multiple of the fundameptal frequency produced in the primary 001 s.

6. Transmitting station for radio telegraphy and telephony comprising means for producing current of a desired fundamental frequency, a suitable number of frequency changers having primary and secondary coils and a primary circuit connecting the primary coils with said producing means, a circuit operatively connecting said secondary coils with said primary coils and an oscillation circuit having means for tuning it to a higher frequency than that of the primary circuit, said oscillation circuit bein conductively connected in parallel to sai primary and secondar coils to produce any desired uneven multiple of the fundamental frequency according to the adjustment of said tunin means.

7. ransmitting station for radio telegraphy and telephony comprising means for" producing current of a predetermined fundamental frequency, a suitable number of frequency changers and a suitable circuit connection for same to receive the currents of fundamental frequency from said producing means, said changers also having circuit connections causing currents to flow in said coils of double the fundamental frequency, whereby said coils are connected as auto-trans formers.

8. Transmitting station for radio telegraphy and telephony comprising means for producing alternating current of predetermined fundamental frequency, a suitable number of frequency changers having primary and secondary coils and circuits suitably connecting said coils to produce in the secondary coils an alternating current of a multiple of the fundamental frequency, means for supplying auxiliary magnetizing current to said changers, said auxiliary current passing through one of said two kinds of changer coils.

9. Transmitting station for radio telegraphy and telephony having an antenna, and means for tuning it, an alternatin current generator for producing a desire funincense damental frequency and a suitable number it by said changers to produce through the of frequency changers being disposed beresulting frequency interference beats of a tween the generator and the antenna, suitpredetermined frequenc able circuits connecting said changers to In testimony whereof we affix our signa- 5 multiply the fundamental frequency of said tures in the presence of two Witnesses. 15

generator, tuning means in said circuits for GEURG VON ARGO. tuning the latter to the frequencies of the ALEXANDER MEISSNER. currents passing therethrough, the natural Witnesses: frequency of said antenna being slightly HENRY HASPER,

different from the frequency impressed upon WOLDEMAR HAUPT.

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