Basic Electronics Paper 2, May/June 2015

Question 6

  1. State two differences between a 625 line monochrome and colour television receivers.
  2. In a 625 line colour television receiver, state the frequency of the following units:
  3. (i) horizontal oscillator; (ii)vertical oscillator; (iii)sub-carrier; (iv) sound frequency.



       The expected answers were:

 (a)         (i)  Monochrome Television Receiver has one electron gun whilst the colour television has three electron guns.

(ii) Monochrome Television Receiver has a single raster whilst colour television has three rasters.

(iii) Monochrome Television Receiver has a single video signal whilst a colour television receiver has two video signals (luminance and chrominance signals)

(b)         (i)         Horizontal Oscillator   -  15625 Hz.
(ii)        Vertical Oscillator       -  50 Hz                                              
(iii)       Sub carrier       -  4.43 MHz                                        
(iv)       Sound frequency          -  5.5/6 MHz 

The question was on Communication Systems. The question was popular with the candidates. The performance was fairly good.