chapter  3
9 Automatic gain control
Pages 2

The basic superhet receiver shown in Figure 3.11

has an intermediate frequency (IF) of usually

either 455 kHz, 1.6 MHz or 10.7 MHz. In order

to achieve an acceptable degree of image channel

rejection (recall that the image channel is spaced

by twice the IF away from the wanted frequency)

a 455 kHz IF will generally be satisfactory for the

reception of frequencies up to about 5 MHz,

whilst an IF of 1.6 MHz (or greater) is often used

at frequencies above this. At VHF, intermediate

frequencies of 10.7 MHz (or higher) are often

used.