The MONACOR SWR-2 is a combined SWR (Standing Wave Ratio) and Field Strength Meter designed to help users tune their CB or amateur radio systems for optimal performance. It is a crucial tool for ensuring that the antenna system's impedance closely matches the transmitter's output impedance, thereby maximizing transmitted power and minimizing signal loss.
Function Description:
The device serves two primary functions:
- SWR Measurement: This function measures the amount of transmit power reflected from the antenna back into the antenna cable. High SWR indicates wasted power, which generates heat and reduces the efficiency of the radio system. By measuring SWR, users can adjust their antenna or antenna cable length to achieve the lowest possible reflection and maximize power output.
- Field Strength Measurement: This function measures the low levels of radio frequency (RF) generated by a radio transmitter. It allows users to map the transmitting direction and coverage pattern of their antenna. This is particularly useful for comparing the radio and antenna's efficiency before and after adjustments, helping to optimize antenna placement and configuration for the best coverage.
Important Technical Specifications:
While specific numerical technical specifications like frequency range or power handling are not explicitly detailed in the provided manual pages, the manual implies the following:
- Impedance: The meter is designed for use with 50-ohm coaxial cable systems, such as RG-58U.
- Connectors: It uses PL-259 connectors for connecting to the radio and antenna.
- Measurement Scales:
- SWR Scale: Ranges from 1 to 3, with an ideal reading of 1.0. It also includes a "% REF POWER" scale, indicating the percentage of power lost due to reflection (e.g., 1.5 SWR corresponds to 4% reflected power).
- Field Strength Scale: Ranges from 1 to 5, used for relative field strength measurements.
- Modes of Operation:
- For SWR measurements, it is recommended to use AM mode for CB radios and CW (Continuous Wave) or tuning mode for amateur radios. Sideband modes (SSB) should not be used for SWR measurements.
- For Field Strength measurements, AM mode is recommended for CB radios and CW or tuning mode for amateur radios.
Usage Features:
- Ease of Connection: The meter connects in-line between the radio's antenna jack and the antenna. A separate 50-ohm coaxial cable with PL-259 connectors on both ends is required for this connection.
- Simple Calibration and Measurement (SWR):
- Set the front switch to "FWD."
- Transmit on the radio (without speaking).
- Adjust the "LEVEL ADJUST" sliding control until the needle points to "SET."
- Release the transmit key, then set the switch to "REF."
- Transmit again and read the SWR on the upper scale.
- Interpreting SWR Readings: The manual provides a clear table for interpreting SWR readings:
- 1 to 1.5: Excellent (Antenna cable and length match transmitter's output almost perfectly).
- 1.5 to 2.0: Very good (Antenna, cable, and transmitter operate efficiently).
- 2.0 to 3.0: Acceptable (Some loss; adjustment recommended).
- Above 3.0: Inefficient (Likely to cause damage to transmitter; adjustment strongly recommended).
- Improving SWR: The manual offers practical advice for improving SWR, including:
- Using the correct type of coaxial cable (50-ohm).
- Ensuring proper antenna mounting according to the manufacturer's instructions.
- Adjusting the antenna length (even small changes like 1/16 inch can make a difference).
- Consulting radio and antenna owner's manuals.
- Field Strength Measurement (Two-Person Operation):
- The meter does not need to be connected to the radio or antenna for field strength measurements.
- It requires two people: one to transmit and one to walk around the antenna with the meter.
- Site Preparation: Involves marking a circular path around the antenna (e.g., 25 feet radius) with 36 evenly spaced marks. A compass is used to establish due north. A formula is provided to calculate the spacing between marks (diameter / 11.46).
- Calibration and Measurement (Field Strength):
- Ensure the wire antenna is inserted into "FS ANT."
- Set the FWD/REF switch to "FWD."
- While the helper transmits, walk around the marked circle and adjust the "LEVEL ADJUST" control until the needle points to 5 on the FIELD STRENGTH scale.
- Move to each marked spot, and while the helper transmits, note the reading on the FIELD STRENGTH scale and mark it on a template.
- Tuning with Field Strength Readings: Field strength measurements help monitor the effectiveness of changes like installing new antennas/cables, adjusting antenna length/mount, or adjusting the transmitter. Higher field strength readings indicate improved power output and efficiency.
Maintenance Features:
The manual does not explicitly detail maintenance features for the device itself. However, it implicitly guides users on maintaining their radio system's performance through its measurement capabilities:
- Preventative Damage: By identifying high SWR readings (above 3.0), the meter helps users prevent potential damage to their transmitter, which can occur due to excessive reflected power.
- System Optimization: The SWR and field strength measurements enable users to continuously optimize their antenna and radio setup, ensuring long-term efficient operation and potentially extending the lifespan of their equipment by operating it within optimal parameters.
- Safety Warning: The manual includes a warning about high voltages when making measurements, emphasizing the importance of observing all safety precautions provided with the equipment being tested. This highlights a crucial aspect of "maintenance" in terms of safe operation and preventing harm to the user or equipment.
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