SU56146A1 - Self-excited tube generator - Google Patents

Description

This invention relates to an ultrashort wave generator driven by self-excitation.

When operating self-excited tube oscillators, which have a conventional scheme, on ultrashort waves, the efficiencies are much lower than when operating on longer waves. The reason for this phenomenon is that due to the inertia of the electrons, a phase shift occurs between the control voltage and the first harmonic of the anode current of the lamp, i.e., the anode current is delayed compared to the control voltage. The phase angle increases in proportion to the shortening of the wavelength. Its value can be approximately determined by the formula

3600 g

YU:

Here is the voltage at the anode in volts, r is the anode radius in centimeters, X is the wavelength in meters.

It is easy to see that already at waves with a length of 5-10 m, this angle reaches a considerable value. For example,

for lamp GUO-500 at L 4000 volts, g 2.5 cm, X 5 m, we have

3600

2.5 5

1800

   QO

, g- 7:

65

K 4000

In fact, in the generator mode, -; that angle is even greater, since the anode current when operating with a small cut-off occurs in that part of the high frequency period when the anode is under reduced voltage, which is necessary to obtain a satisfactory efficiency factor.

The presence of the intra-tube phase shift does not reduce, as the relevant calculations show, the coefficient of efficiency of the generators operating with independent excitation. In self-excited oscillators, this phase shift should be sharply reflected in the coefficient of efficiency. Indeed, the tube oscillator generates the frequency at which the phase balance occurs in the self-excitation circuit. Therefore, in the presence of intra-shear with conventional circuits, the frequency will be generated at which

to have an equal and reverse magnitude phase shift of the anode circuit. In other words, during self-excitation, the anodic circuit will be upset with respect to the generated frequency. When the same anode circuit detuning decreases the coefficient of useful action.

The present invention aims at eliminating said adverse effect of the intra-tube phase shift caused by the inertia of the electrons, as well as in some cases for other reasons (for example, the presence of harmonics in the control voltage).

The essence of the invention is that the self-excitation circuit is composed in such a way that the feedback phase, more precisely, the phase shift between the control voltage and the voltage at the anode of the lamp, is equal to and opposite in sign to the intra-tube phase shift (more precisely, phases between the anode current and control voltage). In this case, obviously, the frequency to which the anode circuit is tuned will be generated.

This can be achieved, for example, by performing an auto-oscillator as shown in the drawing. In this scheme, feedback through the capacitance of the anode-grid of the lamp is eliminated in a different way, for example, using neutrodyn circuits and lamps with a shielded anode. The feedback takes place via a quadrupole / turning the phase to the desired angle. The quadrupole 2 is a high frequency transformer that raises or lowers the voltage to the desired value. Practically, the quadrupole 1 can be implemented either as a line with distributed constants of the desired length, or as a filter of one type or another.

If the intra-tube phase shift is and transformer 2 does not introduce a noticeable phase shift, then, if a line with distributed constants is used, the phase shift in it should be equal to minus P + 2kl, where k is any integer. If, in addition, the transformer 2 and its connection with the line are made so that there is in the line

pure running wave, then phase shift,

9g / given by the line will be equal to -

where / is the length of the line. Equating zero sum of phase shifts, we have

--B oh oh

i from

/: ZpH-- -X.

A- - 1

 jP / 9 °

    Hlpr

360 ° /

27: 9 30 °, then

/ -1h 12

Thus, the line length should be slightly shorter than the wavelength. If the line length is desired to be made smaller, then the ends of the line can be crossed, which will give an additional phase shift of 180 ° and thus allow the length to be shorter by half. With intra-tube phase shift of 30 ° the length of the line

" five

will be - wavelength.

X

Transformer 2 can be performed in many ways, for example, in

oscillation circuit view, in the form

resonant line, in the form of a bridge from

self-inductance and capacitance, etc.

A mixed wave can also occur in line /, In this case, its optimal length will be different.

The subject matter of the invention.

1. A self-excited lamp oscillator, characterized in that as a feedback element between the anode circuit and the grid, a device is used that creates a phase shift between the control voltage of the grid and the anode voltage, which is approximately equal to and opposite to the phase shift that occurs inside lamp between the main component of the anode current and control voltage.

2. The form of the generator according to | phase shift, applied lines with spacing. I with weakened or eliminated feedback through the capacitance of the anodocete of the lamp, characterized in that as a device creating

strange constant or filter associated with its beginning with the anode circuit and its end with the grid circuit.