The AA8V 6x2 Superheterodyne Receiver
by Greg Latta, AA8V

AC Primary Circuit Schematic Diagram and Circuit Description

AC Primary Circuit
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Schematic Diagram and Circuit Descriptions Page

Introduction:
The primary wiring of the 6x2 receiver is straightforward. A grounded 3-wire cord supplies power and keeps the chassis grounded at all times in case of a component failure. A fuse protects against excessive current draw, and a power switch, part of the Mode switch, applies primary power in the AM and CW modes. Two bypass capacitors also shunt each side of the AC line to ground to prevent any RF from entering or leaving via the line cord. (RF leaving via the line cord could include oscillator harmonics that could cause TVI, and RF entering via the line cord could include RF from the transmitter.)

AC Primary Circuit
Click On A Section of the Schematic
Below for Information on That Part of the Circuit:
AC Primary Circuit Transformer Primary RF Bypass Capacitors Mode Switch Fuse 3-Wire Grounded Cord

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AC Primary Circuit
 3-Wire Grounded Cord
 Fuse
 Mode Switch
 Power Transformer Primary
 RF Bypass Capacitors


AC Primary Circuit:
 
3-Wire Grounded Cord:
The 6x2 receiver is powered by a 3-wire grounded cord. The third wire keeps the chassis connected to ground. If any component should short to ground, the chassis remains at ground potential, protecting the operator.
3-Wire Cord


 
Fuse:
A fuse in the hot lead of the AC supply protects against excessive current draw that could damage components or start a fire.
Fuse


 
Mode Switch:
One section of the Mode switch is used as a power switch. Power is applied to the transformer primary in the AM and CW positions of the switch.


Mode Switch


 
Power Transformer Primary:
The power transformer is a Chicago Stancor PC-8405. The transformer cost $10.30 as listed in a 1967 Allied parts catalog.

The transformer ratings are as follows:
Primary: 117V at 60Hz
HV Secondary: 540V CT at 120mA
Filament Secondary #1: 6.3V at 3.5A
Filament Secondary #2: 5V at 3A
Transformer Primary


 
RF Bypass Capacitors:
To prevent any RF from entering or leaving via the line cord, each side of the AC line is connected to ground via a 0.001uf capacitor. The capacitors short to ground any RF, but have very high reactance at 60Hz, so they have no effect at 60Hz.


RF Bypass Capacitors


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