DE1061390B - Transmitter circuit with modulated output stage in grid base circuit - Google Patents

Description

In the case of high-frequency transmitters, it is known to be advantageous to feed the message, ie the modulation, as close as possible to the output stage. At. The efficiency is transmitters broadcasting _r increased by - while thus avoiding the difficulties in television, which otherwise many high-frequency amplifier stages arise in broadband matching.

If the modulation is carried out in a high-frequency stage with high power (e.g. in the output stage), and if this stage is operated in a grid basis circuit, the modulation process has the result that the grid resistance of the output stage is changed in time with the modulation, because the anode and Grid alternating current of the modulation stage operated in the grid basis circuit is transmitted via the controlling High frequency source closes. Since a constant alternating grid voltage is desired during the modulation process is, these fluctuations in the external resistance of the preliminary stage have the disadvantage that the Anode alternating voltage of the preliminary stage and thus the input voltage of the modulation stage fluctuates, and the more so, the greater the internal resistance of the preliminary stage to the fluctuating external resistance is.

The invention relates to a transmitter circuit with an output stage operated as a grid base circuit in which these defects are avoided, d. H. their high-frequency input voltage when performing a Modulation process in the output stage is constant. So far, triodes have been used to solve this problem used as precursors in such transmitter circuits, but especially in the VHF range Have disadvantages. In such a transmitter circuit it is also already known, one as a grid base circuit operated modulated output stage from a driver stage equipped with a triode via a feed line adjustable in length, so that the inherently small internal resistance of the driver stage also appears as a small resistance at the input of the output stage. But this type of construction requires a relatively high tax output.

A significant improvement is achieved according to the invention that the output stage with a Preamp with multi-grid tube is connected in a known manner via a network, which consists of an odd number of Z / 4 members. The invention is based on the intention on which on Input of the modulation stage lying, in the clock of the modulation fluctuating resistance approximately a to achieve constant terminal voltage. Since the multigrid tube in the preliminary stage has a practically constant Supplies current, the constant input voltage at the modulation stage is reversed by

Transmitter circuit with a modulated output stage in a basic grid circuit

Applicant:

Siemens & Halske Aktiengesellschaft,
Berlin and Munich,
Munich 2, Wittelsbacherplatz 2

Dr.-.Ing. Rudolf Hofer, Berlin-Siemensstadt, has been named as the inventor

proportional transformation of the presupposed high internal resistance of the preliminary stage achieves a small value at the input of the modulation stage.

The network used so far is in an amplifier circuit between a screen grid tube or pentode and a tube operated in cathode base circuit became known in the area positive grid voltage is controlled and for which a carrier modulation was not provided.

In an older, unpublished patent application, a transmitter circuit is proposed, in which a grid base output stage, in which no modulation is carried out, via a network is connected to a pre-stage with a multi-grid tube. This is intended to solve a different problem , namely the fluctuations in the reactive component of the input impedance of the output tube, which are im Range of decimeter waves and even shorter waves due to the already very noticeable electron transit times are caused to compensate.

The invention consists in a combination of individual features known per se, which boils down to that a certain network with reciprocal transformation in a transmitter circuit between a Driver stage with multi-grating tube and a modulated grating base output stage is used, with the beyond the technical progress going beyond the individual features is achieved that the transmitter with a small control power while at the same time keeping the high-frequency input amplitude constant the modulated output stage gets by.

An embodiment of the invention is shown in FIGS. 1 and 2, wherein

909 577/299

Claims (1)

1 shows a basic circuit diagram of the transmitter circuit according to the invention and Figure 2 illustrates an embodiment of the reciprocal transform network. A multi-grid tube 1 (Fig. 1) located in the preliminary stage of a transmitter is connected to the input of a grid-based circuit and z. B. anode-side modulated end tube 2 connected via a network 3 . This network is dimensioned in such a way that the input resistance of the output tube 2, which fluctuates in time with the modulation, is transformed inversely proportionally to the anode side of the preamp tube 1. For this purpose, a network 3 shown in FIG. 2 is used, which consists of three so-called X14c members, in which the impedances X _v, X ₂ and X ₃ in the series branch are as large as the impedances in the shunt branches. Claim:
Transmitter circuit with output stage operated as a grid base circuit, the high-frequency input voltage of which is constant when a modulation process is carried out in the output stage, characterized in that the output stage is connected to a pre-stage with multi-grid tube in a known manner via a network which consists of an odd number of X / 4- links. Considered publications:
German Patent Nos. 726 512, 1013 328; British Patent No. 738,409;
French Patent No. 939 045;
U.S. Patent No. 2,571,045;
"FTZ", 1953, no. 8, p. 396/397. 1 sheet of drawings © 909 577/299 7.59