Your Power Supply and RF Output Power

3. Connect a dummy load to J1, the amplifier RF output. In a pinch, a light bulb may be used - see the section, "Verifying RF Power Output."

4. Temporarily install a jumper from the collector of Q3 to ground.

5. Apply power to the amplifier but do not turn on the transmitter. Measure the current drawn by the amplifier and slowly rotate the bias pot, R4, clockwise until you reach a reading of ¼ amp. Do not allow the current to rise above ½ amp. If you cannot adjust or reduce the current, disconnect the power supply and consult the troubleshooting hints section. The voltage at TP1 should be about 3.2 to 3.5 volts.

6. Turn off power. Disconnect jumper from Q3 to ground.

7. Connect the QRP transmitter to the input of the amplifier. Key the transmitter. You should hear the T-R relay click and see amplified power output. Measure the DC current draw; it should be in the 1 to 3 amp range depending upon power output. Unkey the transmitter. The relay should drop out and the current should drop back down to ¼ amp

This completes the testing of your QRP power amplifier. The PC board should be mounted into a protective enclosure to guard against accidental contact. The Ramsey CQAMP case set provides an ideal perfectly sized cabinet that matches all other Ramsey kits.

Study the following sections on DC power supply and RF power considerations. Operate your transmitter with good amateur practice.

For optimum performance, one or two volts of extra DC supply power can make quite a difference in any RF power amplifier. For example, two lantern batteries in series, or 8 D cells, will obviously provide about 12 volts with sufficient current capability for casual operating. For maximum RF output power, use a supply of 13 to 14 volts DC. The easiest method is to place two fresh D cells in series with your power source if a full 13.6 - 15 volts DC is not available. Be aware that batteries are not the optimum power source, especially if you are prone to long QSOs! A word of caution concerning wall plug style AC adapter power supplies: They are not suitable for operation of your amplifier due to their poor regulation, AC ripple content, and RFI susceptibility.

With 1 watt of drive and a supply voltage in the 11-12 volt range, you can expect a 1 to 2 amp current draw and about 10 watts of RF output power. With a solid 13 to 14 volt supply, you can expect about 2 to 3 amps current draw and up to 10 or 12 watts of RF output power. With 2 watts of RF drive, expect up to 20 watts RF output!

QAMP-30 • 13

QAMP30 specifications

Ramsey Electronics QAMP30 is a versatile audio amplifier designed for a range of audio applications. This compact yet powerful amplifier is specifically engineered to provide quality sound in a small footprint, making it ideal for home audio systems, portable audio setups, and compact installations.

One of the main features of the QAMP30 is its robust 30-watt per channel output, delivering clear and dynamic sound that can fill a room. Its solid state design ensures reliability and durability, making it suitable for both casual listeners and audiophiles. The amplifier supports continuous operation, allowing users to enjoy music for extended periods without worrying about overheating or performance degradation.

In terms of connectivity, the QAMP30 is equipped with multiple input options. It includes RCA inputs for easy connection to various audio sources, such as televisions, DVD players, and computers. This flexibility allows users to integrate the amplifier seamlessly into their existing audio setups. Additionally, the amplifier features a 3.5mm auxiliary input, further expanding its compatibility with portable devices like smartphones and tablets.

The QAMP30 also incorporates advanced circuit design technologies to enhance audio performance. Its low noise floor and high signal-to-noise ratio ensure that audio playback is clean and free from unwanted distortion. This feature is particularly important for critical listening environments where audio fidelity is paramount.

Moreover, the QAMP30 has an integrated volume control knob, giving users direct access to adjust their listening levels easily. The simple, user-friendly interface and compact design permit versatile placement in various setups, whether on a shelf, desk, or installed within a larger audio system.

Furthermore, the amplifier is equipped with built-in protection features, such as thermal overload and short-circuit protection, safeguarding the device and connected audio equipment from damage. The overall build quality of the QAMP30 reflects Ramsey Electronics' commitment to producing reliable and effective audio products.

In summary, Ramsey Electronics QAMP30 is a compact, powerful audio amplifier featuring 30 watts per channel output, multiple input options, advanced circuit technologies, and built-in protection features. Its user-friendly design and high-performance characteristics make it an excellent choice for anyone looking to enhance their audio experience.