Ramsey Electronics PA1 Instruction Manual download pdf (Page 11)

PA-1 • 11

INITIAL TESTING

Required for testing:

• 1 to 5 watt 2 Meter transmitter or transceiver.

• 12 volt DC power source, 5 amp minimum.

• RF wattmeter suitable for VHF use.

• Correct cables and connectors.

• 50-ohm 30-50 watt dummy load (use antenna for testing only in accordance

with appropriate frequency selection, transmission ID procedures).

DC voltage may be applied to the PA1 at all times. As a Class C amplifier, it

draws current only with RF drive. For the first test, use just 2 or 3 watts of RF

drive. NEVER exceed 8 watts!

Adjustment is accomplished by turning all 4 trimmers for maximum RF power

output. However, to keep this procedure from becoming like trying to crack a

combination lock, do it in this order:

❒ 1. Turn both compression trimmers (C1,C3) fully clockwise.

❒ 2. While turning C2 (RF input side), watch for a sudden peaking of RF

output. C2 has the most direct and critical control over the driving of Q1.

❒ 3. After some power output is noted from peaking C2, then adjust both C3

and C4 for maximum output. Then readjust C1 and C2 as needed.

That's all there is to it! If you cannot get the proper amount of power output or

gain, there is something wrong with the amplifier or test set-up that needs to be

corrected before further tests are conducted.

TROUBLESHOOTING HINTS:

The amplifier should produce at least 8 to 10 times power gain, for example: 2

watts in for 20 watts out. If the amplifier does not give you this gain, make sure:

C5 and C6 are tight, snug against Q1 with virtually no lead length.

Good RF wiring technique was used in hooking up the coax input and output

leads - short lead length on the coax shields and center conductor wires.

Proper adjustment of all trimmers.

At least 12 volts actually measured at the PC board power connection point.

Maybe an SWR problem? Change input and output coax lengths.

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Ramsey Electronics PA1 Instruction Manual Page 11