Modern TV channel selectors BELVAR. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Телевидение

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Models of television channel selectors manufactured by JSC "Minsk Instrument-Making Plant" with the trademark "BELVAR" are listed in Table. 1. It also indicates the functionality of selectors, some circuit design differences, analogues. It should be added that all selectors do not have an AFCG voltage supply terminal and all models are equipped with an IEC type antenna socket.

By the beginning of 2000, many once popular models of plant selectors (SKV-101, SKV-103, SKV-151, SKV-201, SKV-210) were discontinued. Nevertheless, the produced selectors quite fully reflect the main directions of their development: cable (cab) or all-wave (all), with voltage synthesis (VST) or frequency synthesis (PLL), with a supply voltage of 12 V or low-voltage (5 V).

The designation of selectors has developed historically. It consists of the letter abbreviation SKB (all-wave channel selector) and (with a hyphen) three digits. The first of them initially served to distinguish one series of developments from another, for example, SKV-101, SKV-201. But recently, in connection with the development of low-voltage selectors, this figure has been used to indicate the supply voltage: 3 - 12, 4 - 5 V. The next figure now characterizes the type of selector: cable models are assigned the number 0, and all-wave - 1. The last figure reflects the method settings used in the selector: for PLL - 0, and VST - 1. Variants of selectors SKV-301 and SKV-310 with an extended antenna input of 32,2 mm are supplemented with the letter L (Long).

The appearance of the selectors and their main dimensions are sketched in the figure, and the pin assignment is shown in Table. 2

 It should be borne in mind that the reading of the conclusions in all selectors is carried out from the side of the antenna socket. Contacts K of the housing are used to connect to a common wire. The following designations are used in the table: UnviT - supply voltage; UH - tuning voltage; Counter. UH - setting voltage control output; UPLL - synthesizer supply voltage 5 V.

(click to enlarge)

Models of the 4,45th series are made according to European standards for unifying the design: pin spacing is 4 mm, symmetrical IF output. The 11th series complies with new world standards: pin spacing is XNUMX mm with a maximum of XNUMX pins.

The breakdown into subbands of the received frequencies of cable models of selectors (SKV-301 .SKV-401) differs from that indicated in [1] so that all cable channels are concentrated in subband B. The subbands include the following frequencies (channels), in MHz:

• A - 48...111 (1-5);
• B - 111 ... 300 (K1-K18, 6-12);
• C - 470...862 (21-69).

Sub-range C for all models of selectors is extended to the 69th channel. Therefore, in the last two sub-ranges B and C there will be an increased "sharpness" of tuning. Therefore, more stringent requirements should be imposed on the stability of the tuning voltage and the smoothness of its change, as well as on the APCG system.

The main electrical parameters of the considered selectors are summarized in Table. 3. In it, the values ​​indicated in brackets refer to sub-band B. It should be noted that the gain of the SKV-301 and SKV-310 models in sub-band B is noticeably lower than in the other sub-bands. As a result, the uneven frequency response over the entire range of received frequencies in these selectors reaches 8 ... 9 dB, although within each sub-range (A, B or C) does not exceed 4 dB.

Comparison of BELVAR models in terms of such parameters as the depth of automatic gain control (AGC) and selectivity for the image channel in sub-band B, which is 50 dB (in sub-bands A and C - 60 dB), with similar or similar models manufactured by SELTEKA JSC "[1, 2] shows that they are somewhat inferior to the latter. However, the SKV-411 selector compares favorably with its economy: its current consumption is 20...25 mA less than that of the similar selector KS-H-131 (JSC "SELTEKA").

The lower voltage limit of the VST selectors is set to 0,5 V (against 0,7 V for analogs), which must be taken into account when installing them in modernized TVs. This is especially true for devices in which the SK-M-24 selector is replaced, which has a lower tuning voltage limit of 1 V or more. Selectors with frequency synthesis (P1_1_) are represented by two models, a characteristic feature of which can be called the absence of the READING mode. The first of them (SKV-310) is the most developed model. It provides for the installation (by software) of the tuning step equal to 62,5 and 31,25 kHz. The tuning speed in the selector is slowed down when approaching the broadcast channel to reduce residual detuning. The selector uses the MC4418 synthesizer from MOTOROLA, which implies the use of its own control processor.

Specified in table. 1, as an analogue of this model, the KS-H-92 selector was modernized by the beginning of 1999, as a result of which its functionality and control system have changed [2]. Therefore, with a strict approach to interchangeability, it would be correct to consider as an analogue the version of the selector that was produced before its modernization.

In table. 4 shows two control bytes in the WRITE mode for the SKV-310 selector.

Changing the hopping speed is provided by bit P14: its state 0 leads to slowdown. The tuning step is set by bits P11 and P10. If they are the same (both in 0 or in 1), the tuning step is 62,5 kHz, if they are different (combinations 01 or 10) - 31,25 kHz. Bits РЗ-Р0 are responsible for switching subbands in accordance with Table 5.

Information about the bytes of the address and program divider, as well as the states of the address selection bits (MA1 and MAO) are available in [2, table. 5 and 6] and can be used for this selector.

Model SKV-410 is one of the latest developments. In it, you can set three values ​​for the restructuring step: 62,5; 50 and 31,25 kHz. The rest of the feature set is the same as the previous model. Since the selector supply voltage is 5 V, it is not necessary to separately supply voltage to the synthesizer (Upll = 5 V), and selector pin 2 is used to control the tuning voltage. The selector uses the TSA5522M synthesizer.

It should be borne in mind that in the original material [3] the UV1316 selector, declared as an analogue, as well as the KS-H-132 model, have wider functionality. Replacing them with the SKV-410 selector is possible, but only with the loss of the READING mode and the absence of a five-level ADC (ADC).

As for the control of the selector SKV-410. then it in the RECORDING mode does not differ from the analogs of PHILIPS and JSC "SELTEKA" considered in [2].

Schemes for switching on selectors (in general form) are presented in [1]. Recommendations on the use of models with a symmetric IF output and their coordination with the blocks of the radio channel SMRK-1-5 (SMRK-1-6, SMRK-2-1) are given in [4].

Literature

1. Burkovsky A. Modern television channel selectors. - Radio, 1999, No. 6, p. 6,7; No. 7, s-8, 9.
2. Burkovsky A. Modern TV channel selectors with frequency synthesis. - Radio, 2000, No. 5, p. 7-9.
3. Advertising and information materials "BELVAR" for 1999 and 2000
4. Burkovsky A. Selector KS-H-930 in TVs of the 3rd-5th generations. - Radio, 2000, No. 12, p. eleven.

Author: A.Burkovsky, St. Petersburg

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