14 to 15 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.

If your supply voltage is in the 11-12 volt range, you can expect a 200 to 250 ma current flow and about one-half watt of the RF output power. With a solid 14 to 15 volt supply, you can expect about 400 ma current draw and up to 3/4 watt of RF output power.

VERIFYING TRANSMITTER RF OUTPUT:

The most important thing to know is whether your transmitter is delivering some measurable and reassuring level of RF power to the antenna. The sound of the transmitter's keying in a receiver is of some help, but even the simplest crystal oscillator can send a fine signal into your neighbor's receiver, as we have already discussed.

Ideally, you have an small RF wattmeter, already inserted in the antenna line, capable of accurately measuring low output power in watts and even milliwatts! And it cost you less than what you paid for the transmitter kit. Right?

If not, we have a few other ideas for you, OK?

Saying the same thing one more way, we assume you already know that accurate, commercially built RF wattmeters cost much more than what you paid for this Ramsey transmitter kit.

Since this solid-state transmitter does not require tuning or adjustments, a periodic power output check-up should suffice. If you do not own or have access to a low-level RF power meter, use a trick that is decades old, the common flashlight or panel bulb. All you need to know is the basic differences between bright, superbright, dim, unlit and burned out! Using such a bulb to check power output is also a satisfying way to put Ohm's Law to work. Your Radio Shack catalog specifies operating voltage and current in milliamperes for a variety of small replacement lamps. It could be worth your time to make up a simple plug-in "output tester" for your transmitter, a male RCA plug connected to a socket for the bulb of your choice or even soldered directly to the bulb.

Rf voltage levels in this transmitter can vary from 2 to 10 volts RMS depending on various factors. Typically, 1 watt power levels are achieved in 5-7 volts RMS volts range. A good test bulb for this level is the PR-4 flange-style flashlight bulb or the type 243 bulb with screw-in body. Both are rated to give normal brilliance at 2.33 volts, drawing 270 milliamps of current. Using Ohm's Law P=IE, we see that normal brilliance requires 2.33 volts x .270 amperes for .62 watts of DC power consumption. We can conclude that even 1/2 watt or so of RF should light this bulb reasonably well. A type PR-12 bulb is suitable for checking RF outputs in the 1-3 watt range. Try it out!

QRP-20 • 18

Page 17 Page 19
Page 18
Image 18
Ramsey Electronics QRP20 manual Verifying Transmitter RF Output
Page 17 Page 19

QRP20 specifications

The Ramsey Electronics QRP20 is a compact and innovative low-power transceiver designed for amateur radio enthusiasts who appreciate both portability and efficiency in their operations. This QRP (low power) radio is primarily aimed at those who seek to operate on the HF bands, providing an exhilarating experience for operators who thrive on the challenges and satisfaction of making contacts with minimal power output.

One of the standout features of the QRP20 is its compact design. This radio can easily fit into a backpack, making it ideal for field operation, portable use, or emergency communication scenarios. Weighing in at just a few pounds, it’s lightweight enough for extended outings without burdening the operator.

The QRP20 operates on a range of HF bands, specifically covering 20 meters, which is especially popular among amateur radio operators for its relatively consistent propagation and activity level. The transceiver leverages solid-state technology, ensuring reliability and optimizing performance. It can produce an output of up to 5 watts, which is standard for QRP operations, allowing operators to experiment with different antenna configurations and propagation techniques.

Another significant aspect of the QRP20 is its user-friendly interface. The radio features a straightforward layout with well-placed knobs and buttons for efficient tuning and operation. The built-in digital display provides clear visibility of frequency information and operational status, enhancing the overall user experience. In addition, the QRP20 includes a narrow bandwidth filter, which effectively reduces noise and enhances signal clarity, enabling clearer communication even in crowded band conditions.

The QRP20 is equipped with an internal speaker as well as a headphone jack for private listening. It also features a built-in keyer for CW (Continuous Wave) operation, making it versatile for various modes of amateur communication including voice and Morse code.

Powering the QRP20 is effortless, as it can be run off a standard 12V power supply or a rechargeable battery, giving operators flexibility in power sourcing. Whether during portable activations or in a home setup, the QRP20 is adaptable to different operating situations.

In conclusion, the Ramsey Electronics QRP20 is a remarkable choice for amateur radio users who value portability, versatility, and performance. Its efficient design, solid technology, and ease of use make it a compelling addition to any operator's gear, offering a satisfying QRP experience while staying connected with a global community of radio enthusiasts.
Top Page Image Contents