Ramsey Electronics QRP20 manual Building the VXO Variable Crystal Oscillator

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‰18. Install R14, 10K ohms [brown-black-orange].

‰19. Install Q4, be sure to orient its flat side correctly as shown.

‰20.Install C15, .01 uf (marked .01 or 103 or 10 nf).

So far, here's what we've accomplished. First, we've got over a third of all the parts soldered onto the board, which should make you happy, and you should be used to locating the correct component holes with increasing ease by seeing them in relation to previously installed components. Secondly, the keying circuit is completed and would be usable, if there was something to key.

From here, we could proceed one of two ways. It would be quite easy to start filling in the holes around the antenna jack, and the project could be done in perhaps another hour. We'd like to suggest a better approach, which is to build up the VXO stage (variable-crystal-oscillator) around Q1 and test it before finishing the rest of the transmitter.

BUILDING THE VXO (VARIABLE CRYSTAL OSCILLATOR):

Your QRP transmitter comes complete with one crystal in the CW range, usually the suggested QRP international calling frequency. S1 permits your choice of any two installed crystals, the one that comes with your kit and another which you may add on your own. If you plan to add a socket for your own crystal, it should be wired to the "A" crystal position.

The PC board used in your kit is common to all the QRP transmitters in the Ramsey Kit line. This means that there are some component locations on the PC board that may not be used on your kit. Please be aware of this and install your parts carefully. The parts layout diagram is quite clear regarding this. (The reason for these holes is that different frequency bands require various styles of inductors and capacitors for correct VXO frequency and shift).

Now, since we have gone to all this explaining, let's install some more parts!

‰21. Install L1, 2.2 uh inductor (green body with two red bands).

‰22. Install C1, .01 uf (marked .01 or 103 or 10 nf).

‰23. Install R2, 1 megohm (brown-black-green).

‰24. Install Varactor diode D3, observe correct placement of the flat side. (Varactor diodes act as a variable capacitor whose capacity is varied by the voltage applied across it).

‰25. Install varactor diode D4, observe flat side placement.

‰26. Install R3, 1 megohm (brown-black-green).

‰27. Install R4, 10K (brown-black-orange).

‰28. Install C2, 68 pf.

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Contents CW Transmitter Ramsey Transmitter Kits QRP20 20 Meter CW Transmitter KIT Introduction Watts vs 1 Watt Understanding the Difference QRP-20 WHO should USE a QRP TRANSMITTER? Circuit DescriptionBlock Diagram Parts Supplied with QRP20 Transmitter KIT CapacitorsQRP-20 QRP20 Parts Layout Diagram LEARN-AS-YOU-BUILD Transmitter Assembly Strategy First Assembly StepsQRP-20 Building the VXO Variable Crystal Oscillator Halftime Suggestion Buffer and RF Amplifier Wiring Crystal Oscillator TestingFurther Assembly Your Power Supply and RF Output Power Initial TestsVerifying Transmitter RF Output Maximizing RF Power Output TRANS-RECEIVE OperationRamsey Electronics CASE, Knob & Hardware Option Other Enclosure RecommendationsTroubleshooting Guide Final ConsiderationsQRP-20 Ramsey Kit Warranty Ramsey Model NO. QRP20 Meter CW Transmitter KIT

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.
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