How do Ham Radio Receivers Work

Like the transmitters described in Chapter 9, radio receivers also all have the same basic architecture.  Signals from the antenna are amplified and then converted to lower frequencies with a version of a mixer that down-converts a frequency instead of up-converting it as in the transmitter.  After filtering the output signal is that to which we listen. 

Tuning a transmitter is a fairly simply affair.  This is not true for a receiver because most receivers have multiple controls to be able to pull signals from the noise.  These include variable bandwidth filters, noise blankers, noise rejection filters, and specialty filters.  After learning how these work, you will be more able to adjust your own receiver.

A key feature of the receiver design is the "Automatic Gain Control", or AGC.  Many modern receivers allow you to have control over how the AGC operates.  If you do not understand how the AGC works and can be adjusted, you may end up with a receiver that sounds terrible while your friend's down the road sounds great. 
Fred Cady,
Nov 19, 2018, 7:19 PM