PR20 PRE-AMP Assembly Procedure

Soldering nine parts to a PC board is not a big job, but good performance of the PR20 requires attention to keeping all leads as short and neat as possible. The order of parts installation is not critical for this and other small kits, so the purpose of the following suggested order of assembly is just to make it as easy as possible for you to get the parts placed correctly on the first try. For your convenience, the PC board is considerably enlarged. While working with a small PC board such as the PR20, a miniature vise plus a magnifier may prove very helpful.

In all steps below, the word install means to insert the component (oriented correctly) into the right holes, solder all wires, and cut or nip away excess wire flush with the solder connection. IMPORTANT: Keep ALL component leads as short as possible!

1. Install R1, 470 ohm (yellow-violet-brown). Notice from the schematic that R1 determines Q1’s collector voltage and therefore the bias voltage fed by R2.

2. Install R2, 100K ohms (brown-black-yellow).

PR20—6