JPS59126327A - Matching adjustment circuit for tuner - Google Patents

Abstract

PURPOSE:To eliminate the possibility that unnecessary stray capacitance is induced through a lead wire and to make accurately a matching adjustment by composing an adjustment circuit of a capacity circuit including a varactor diode and a variable voltage circuit which includes a variable resistor that varies the capacity of the varactor diode. CONSTITUTION:An antenna tuning circuit (a) consists of an inductance L and a capacity circuit C. The capacity circuit C consists of the parallel circuit of a fixed capacitor 1 and varactor diodes 2a and 2b, and this is coupled inductively with the next stage high-frequency amplifier (b) through a variable inductance 3 which is varied associatively with a push-button device. The variable voltage circuit 4 includes a variable resistor 4' which is connected between an earth terminal and a power source +B while its variable terminal is connected to the connection point P between said two varactor diodes 2a and 2b, and the voltage applied to the varactor diodes 2a and 2b is varied by the varying operation of this variable resistor 4' to adjust the capacity value.

Description

DETAILED DESCRIPTION OF THE INVENTION Motokawa relates to a matching adjustment circuit for a PI adjuster, which makes it easy to adjust the matching legs of an antenna circuit without the influence of stray capacitance.

In general, in a car-mounted 11J antenna, the antenna IE may differ depending on the car-mounted antenna or the position of the car-mounted antenna.
There was a concern that variations in the tuner # of the I-tuning circuit would affect the channel selection function, and we wanted to resolve this concern.

The antenna circuit is equipped with a matching adjustment circuit electrical capacitor.

However, since this trimmer capacitor for adjustment requires external operation τ, it is usually installed in the vicinity of the front panel, so if you release it, you can target two aircraft like a conventional push-button tuner. 6i 157 circuit part in the residential position of the component part
: In the case of a structure consisting of 2 relatively long leads Hk, the trimmer capacitor and the current ff1g+'! -! The omitted part? Therefore, the lead acid picks up the floating capacity and matching FiIl! l
If the trimmer capacitor is installed close to the trimmer circuit, it will be difficult to perform external operation, and it will be difficult to perform external operation. ! The sweeping mechanism of the L-Shinou and Tosutari also had some disadvantages, such as being troublesome.

So does Book 1 Duck have this kind of flaw? It's an improved one.

Its feature is that it is composed of a capacitor circuit including a high-capacity diode and a variable voltage circuit including a variable resistor that varies the capacitance of the '53 transformer diode. Examples are detailed below with reference to the drawings.

Figure HI''i shows a part of a tuner equipped with the adjustment circuit of the present application, and the antenna tuning circuit 1 is composed of an inductance L and a capacitance circuit C. The capacitance circuit C is A parallel circuit with a fixed capacitor (11 and two variable capacitance diodes! 21a, t2i) and
This and the next stage's high frequency 3' 1 width step opening are inductively coupled via the b1 variable inductance (31), which is variable in conjunction with the Shinmei 1 device. (4) is connected to the ground end and the The VC is connected to the voltage ≠, and the variable terminal is connected to the 2
It is a variable voltage circuit including a variable resistor (41') connected to a connection point P with two g capacity 1 diodes t2'a* f2Ib, and the variable capacity diode ( 21a, (21'bK apply'* IE Ka"1 K San Te8 jRt I'l
E is adjusted.

Therefore, according to Honton, since the object to be operated externally is a variable resistor, there is no need to use the lead wire as in the past.
This eliminates the risk of picking up Ij-capacitance, allows accurate matching adjustment, allows the use of a variable resistor that is smaller than a trimmer capacitor, and allows the conversion diode to be integrated into an IC along with other circuit components. Because you can
It has advantages such as being effective in reducing the size of the circuit.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing one embodiment of the present application. L is inductance, C is capacitance circuit, (1) is fixed capacitor (2+a, 12'b is variable capacitance diode,
(41 is a variable voltage circuit, (41' is a variable resistor.

Claims (1)

[Claims] 1. A matching adjustment circuit for a tuner, comprising a capacitance circuit including an angular capacitance diode, and a variable voltage circuit including a variable resistor group for variably adjusting the capacitance of the variable capacitance diode.