SU1298848A1 - Transistor power amplifier - Google Patents

Abstract

The invention relates to radio technicians. The purpose of the invention is to increase K1SC, output power and reliability. The amplifier contains a transistor 1 with an emitter 7, a base 8 and a collector 9, a circuit 2 for matching and bias, a thermopile 3, a flexible heat pipe-diode 4, a housing 5f thermal insulating material (TIM) 6, a nut 10 and a contact washer 11. During the transition in silence mode, when the input signal is absent and the current through the transistor 1 and the thermopile 3 stops, the thermopile 3 loses its cooling effect and the reverse heat exchange between the hot case 5 and the cooler transistor 1 begins. However, the thermal resistance 4 in the opposite direction and an order of magnitude greater than the thermal resistance in the forward direction from the transistor 1 to the thermopile 3. This prevents the spread of heat from the casing 5 to the transistor 1 due to heat conduction and creates conditions for normal heating mode amplifier. To eliminate convective heat exchange, the inner side of the housing 5 is covered with TIM 6, Uejjb is achieved by introducing 4, the length and diameter of which are selected from a predetermined ratio, and performing the radiatf in the form of a housing 5 covered with the inner side of TIM 6. 6. Il. (L N5 x 00 00 00

Description

25

The invention relates to radio engineering and can be used in transmitting devices.

The purpose of the invention is to increase efficiency, output power and reliability.

The drawing shows the construction of a transistor power amplifier.

The transistor power amplifier contains a transistor 1, a matching and bias circuit 2, a thermopile 3, fO a flexible heat pipe-diode 4, a housing 5, a heat insulating material 6, an emitter 7, a base 8 and a collector 9 transistor, a nut 10, a contact washer 11. 15

t

Transistor power amplifier works as follows.

During the time when there is a signal on the amplifier code, the transistor 1 is open and a current flows through it, the constant component of which flows through the thermopile 3 and creates a temperature difference dT up to 30 ° C on it. In this thermopile 3, a cold surface through a flexible heatpipe-diode 4, in which the thermal resistance in the forward direction from transistor 1 to thermopile 3 is at least an order of magnitude smaller than the thermal resistance in the opposite direction, 30 is in thermal contact with transistor 1. When switching to silent mode, when the input signal is absent and the current through the transistor 1 and thermopile 3 stops, the thermobattery 3 loses its cooling effect, the reverse heat exchange between the hot case 5 and more The first transistor 1. However, the thermal resistance of the flexible tube-diode 4 in the opposite direction is large, which prevents the heat from the body 5 to spread to the transistor 1 due to heat conduction and creates conditions for the normal thermal conditions of the amplifier, Dp eliminating convective heat exchange from the inside of the body 5 covered with insulating material 6.

The geometrical dimensions of the flexible heat pipe-diode 4 can be estimated on the basis of expressions that establish the limits of its heat transfer capacity for various limiting factors, which are 45

50 55

steam reduction of the sound speed at the exit from the evaporation zone, excess force of the resistance of the coolant to movement along a closed circuit over capillary forces, interaction of the coolant flows, boiling of the liquid in the evaporator. The first two factors have the most significant effect on heat transfer.

The emission for the sound and hydrodynamic boundaries of the heat transfer capacity of a flexible heat pipe-diode 4 with a plug-in capillary structure is:

(one)

(2)

no steam channel lg

 L,

0.5 (L. + L);

  L

 COP COP

 p..G

the length of the transport, evaporation and condensation zone, y — permeability, cross-sectional area and effective pore diameter of the capillary structure;

P / | lt is a complex parameter characterizing the thermophysical properties of the liquid;

:R,

wed

CV

+ 1 - density

R

heat flux at which the sound limitation occurs; n I {density, surface tension coefficient 0 30 35 40

45

vaporization, dynamic viscosity coefficient of fluid J

9 — wetting angle; q 9.8 m / s;

cf is the angle between the longitudinal axis of the flexible heat pipe-diode and the horizontal plane.

It is advisable to use water as a heat carrier in a flexible 50 heat pipe-diode 4, since for it the values of the parameters N and q x / ri temperature are the best compared to 55 organic liquids. Within the limits of the most probable values of the operating temperature of the cooled output stages of the transmitters (20..2Qfc N (2 ... 5) MO W / m2, q (1 ... 10) 10 W / m2

The value of cos b «1 is relatively easy to achieve in practice.

The heat flux Q through the flexible heat pipe-diode 4 should not exceed the values defined by expressions (1) and (2), i.e. when q, at 1U W / m3 and N 2-10 W / m, we have to fulfill the conditions: Q;

O: O, -. Of which it is easy to get.

  g max

vfakeni setting upper

the limit for the length L of the flexible heatpipe-diode 4 and the lower limit for the diameter of its vapor channel

 , (Lu - LK)

 (3)

due and

D

EF

 cc

  + K sincf

F .. K

The cop

DHK

and

Pc to

f

where cr - K.Q, j., j; c

t / 2.

A transistor power amplifier containing a transistor, a thermopile, connected in series to the emitter circuit of the transistor and mounted 20 with its hot surface on the radiator, matching and bias circuit,

In order to increase efficiency, output power and reliability, a flexible 25 heat pipe-diode was introduced, which is rigidly connected at one end to the cold surface of the thermopile, and at the other end is placed a transistor, while the radiator is filled in the form of

The outcome of constructive conforma- It is advisable to choose the value of the radius of the insulating material for the body covered with internal positions, and

the length L and the diameter D of the flexible heat pipe-diode are chosen from the ratios

k 1,128 -10- m / W

 Yu W / m .kj 2,738 U) W / m,

Q

Max

(g

 Qr

MO let

D

nk

 (1.5 ... 2) 0pk cr. In addition to Dn, dia35

The meter of the flexible thermal tube-diode 4 is made up of its wall thickness, chosen for reasons of strength, and the thickness of the capillary structure, which is limited from above, determined by the heat transfer crisis at heat fluxes much smaller than QMOIKC - The optimum value of L. is determined experimentally and, for example, for the widely used metal-fiber capillary structure LKC (3 ... 4) .- 10-3 m.

45

D 2 (LC LC) +

m / w

f2

where k, (1.7. ..2,2) -10-

The lower limit of the value of L consists of the dpina of the evaporation zones L, and the condensation L, selected from design considerations and from the condition for obtaining the lowest possible thermal resistance between the transistor and the evaporation zone, the thermopile and the condensation zone, and the dpine transport zone C, determined from the condition for obtaining the thermal escro 88484

wall of the flexible heat pipe-diode 4 is at least an order of magnitude larger than its thermal resistance in the forward direction in this way.

1UR ,, S + L,

+ L

to

(five)

fO

where -l and S is the thermal conductivity of the material of the heat-tube-diode wall and its cross-sectional area.

Claims (1)

Invention Formula A transistor power amplifier containing a transistor, a thermopile, connected in series to the emitter circuit of the transistor and mounted with its hot surface on the radiator, matching and bias circuit, 35 d d 45 (four) permeability coefficient, cross-sectional area, optimal thickness, and effective pore diameter of the capillary structure of a flexible heat pipe; Lp, bc, L - thermal conductivity, respectively, p 512988486 cross-sectional spans, QMOKC maximum thermal load of walls, length of the load on flexible thermal evaporation and length of a con-tube-diode zone; Enable flexible thermal, thermal resistance of the tube-tube-diode / Ki-diode in the forward direction.