Construction Notes

Figures Overview

Figure I shows a functional block diagram of the transmitter and receiver as separate circuits, and the simple connection between them to form a transceiver The receiver schematic is divided into two separate drawings, Figures 2 and 3. Points A and B are direct connections be-tw een the tuo receiver schematics.

Figure 4 is ihe transmitter s schematic diagram, When buili as a transceiver, a DPDT switch lakes care of the transmit/receive switching. 1 put this switch on the rear of rig up high where it's easy to reach. One half of the sw itch is used for switching the antenna to the receiver and transmitter. The other half sw itches 12 volts to the receiver^ iiain control line during receive, and supplier \2 volts to the transmitter during transmit.

Receiver

You must remote the internal capacitor from transformer 'IT. Disassemble the trans former and cut the leads carefully with a sharp knife, and pull the capacitor out through the bottom. Take care to not cut the leads of the transformer windings! Capacitor C2 on the circuit board will now determine the tuning range of this transformer.

You must remove a lead from transformers T4 and T5 before installing them on the PC board, because there are no holes provided for them. Transformers T6 and T7 have a mounting tab on their shield cans that also must be removed. Figure 6 illustrates which leads and tabs to remove. Again, careful around the transformer w inding, leads!

Capacitors C34 and C35 are not mounted on the PC board- Thev must be connected between the PC board and switch S5. My first rig had only one capacitor, which was placed between S5 and the volume control R36 Thai arrangement produced a pop in the earphones when the filter was switched in and out.

If you choose to use varactor tuning instead of variable capacitors in the receiver's tunable local oscillator and BFO circuits, then you must make some component connections off of the PC board. This is necessary

[Figure 5 (A), the PC board trace, is continued on page 85,

0 0

Post a comment