This document summarizes the key components and functioning of a chroma signal amplifier circuit and a Yagi-Uda antenna used in a color television receiver. It describes the 5 stages of the chroma signal amplifier, including the first stage involving transistors Q1, Q2 and Q3 for color saturation, color killer bias and burst blanking. It also explains the processing of the composite video signal by the color decoder to extract the U and V color difference signals and the Y luminance signal. Additionally, it provides details on the different sections within the chroma signal amplifier circuit - namely the color saturation control, burst pulse blanking and color killer control sections.

1. Chroma signal amplifier circuit and Yagi-uda antennaBy Ashton

2. Pooja

3. PrathikAVE Colour TVCircuit diagram of Chroma signal amplifier

4. 5 different stages

5. Stage 1(Q1) and 2(Q2 and Q3), colour saturation, colour killer bias and burst blanking pulse stage.

6. Yagi – uda antenna and radiation pattern.

7. Pal – D colour receiverVideo detector suppies composite video signal to colour decoder (pal) and y channel decoder.

8. o/p pal d = V and U ( scaled down colour difference signals U=0.493(B-Y) and V=0.877(R-Y)

9. o/p y channel = luminance (brightness)signal (y)

10. Given to matrix ckt for RGB colour signal generation.

11. Why separation of chroma signal and colour burst signal?The chroma signal separation circuit used.

12. Encoding= process of combining the 2 colour difference signals by translating them to a higher freq. domain.

13. Since the 2 carrier freq. are suppressed in the balanced mod. of the encoder, it is necessary to regenerate them at the receiver for demod. of the chroma signal.

14. So,8-10 cycles of colour sub-carrier oss. o/p are transm. with sync pulses in short bursts called colour burst.

17. Stage 1 (Q1)Input to Q1 via C1Gain controlled by XL1Magnitude of ACC voltage fed to base Q1 via R1 R2C2 avoids undesirable feedback between Q1 and ACC.Ie of Q1 = 0.5Vppo/p to stage 2 via C6o/p to burst stage via C5Function of ACC amp. = o/p Voltage used to control gain of 1st stage of chroma amp. for constant chroma signal amplitude.

19. Stage 2 (Q2 and Q3)Consists of transistors Q2 and Q3Q2 acts as emitter followerQ3 acts as phase splitting amplifier i.e. to provide anti-phase chroma signal for chroma delay line circuit that separates U and V signals.

21. Colour saturation control sectionSaturationDetermines the pureness of the colour.Level of saturation indicates amounts of other colours present in received light.Saturation control section - function is as a variable attenuator to change mag. of the chroma signal led to U and V demodulator.Consists of D1,D2 with R7,R9.