User Manual

Contents:

Sec Topic Page

1 Introduction and General Description..........................32-1

2 Preamplifier Circuit Board Assembly...........................32-2

3 RF Power Amplifier............................................32-2

List of Figures:

Fig Title Drawing Reference

1 PA & Preamplifier Assembly.....................30C1899 sht 1 rev 1

2 Preamplifier Board Assembly, Low Band..........10A1453 sht 9 rev 3

Preamplifier Schematic, Low Band..............10A1453 sht 11 rev 4

3 PA Input Board Assembly, Low Band..............30C1054 sht 1 rev 5

4 PA Output Board Assembly, Low Band.............30C1055 sht 1 rev 3

5 PA Schematic, Low Band.........................30C1056 sht 1 rev 2

6 Preamplifier Board Assembly, High Band.........10A1453 sht 9 rev 3

Preamplifier Schematic, High Band.............10A1453 sht 10 rev 7

7 PA Input Board Assembly, High Band.............20B1222 sht 1 rev 8

8 PA Output Board Assembly, High Band............20B1226 sht 1 rev 7

9 PA Schematic, High Band........................30C1057 sht 1 rev 4

1. RF Power Amplifier & Heatsink Assembly 30C1899G1 - G2 - G3: Figure

The 30C1899 RF Power Amplifier basically consists of a fan-cooled heatsink and

three circuit boards. These boards are the Preamplifier board, the Amplifier

Input board, and the Amplifier Output board. This subassembly is mounted in the

Transmitter Chassis (as an example, see drawing 40D2008 - Figure 1 of the 10W/50W

Chassis section). Figure 1 shows the basic construction of the RF PA assembly.

A directional coupler (example shown as item 15 on the 10W/50W Chassis Assembly

diagram Figure 07-1, and described in the RF Output section of this manual) is

also mounted in the chassis and provides an AGC and metering DC signal

corresponding to the amplifier output RF.

Figure 32-1 illustrates the arrangement of boards on the amplifier heatsink.

Cooling for the PA heatsink is provided by a 4" axial flow Rotron fan which is

mounted on a bracket situated at the end of the heatsink, so that the fan can

extract air through the finned portion of the heatsink. Air exhaust is normally

to the rear of the chassis. If this is not suitable for the application, then

the fan can be mechanically reversed so that it blows air into the heatsink

instead, and this air would then exhaust through the perforations in the front

Comment:

The footer date stamp

must agree with the revision

date. Fix it if it doesn't.

Rev date and footer date must

be the same.