A Large-Display RF Power and
SWR Meter That Speaks
This article is for vision-impaired amateur radio operators interested in the WaveNode WN-2 and WN-2d Station Monitors. These digital RF signal monitors have multiple functions—watt meter, SWR meter, a modulation scope, spectrum analyzer, etc. The large display, voice announcements, and audible tones for tuning are of special interest to vision-impaired hams.
WaveNode loaned a WN-2 unit for this review.
Signal Processing Unit
Each model can be used as a stand-alone RF power/SWR meter. The signal processing unit comes with a coaxial sensor for the frequency and power range of your choice. A wide range of sensors cover frequencies from 1.8 MHz to 1.3 GHz. Up to four sensors can be connected to one monitor.
Figure 1 shows the WN-2 signal processing unit. The dimensions (height, width, depth) are 1.9" x 6.3" x 5.5". The LCD screen displays peak and average power, SWR, and the sensor number.
Figure 1. WN-2 Signal Processing Unit (www.wavenode.com)
Figure 2 shows the WN-2d model, introduced in 2011. The dimensions are 3.1" x 5.7" x 3.8". In addition to an LCD screen, there are two high-brightness LED bar graphs that display the peak power and SWR.
Figure 2. WN-2d Signal Processing Unit (www.wavenode.com)
A wide range of sensors is available to cover all bands from 1.8 MHz to 1.3 GHz. For 1.8 - 60 MHz: One sensor covers 0 - 2,000 watts. A QRP sensor measures 0 - 60 watts. Another HF sensor covers 0 - 8,000 watts. A complete list is here.
More features of a WaveNode monitor are available when it is connected to the USB port of a computer running Windows XP, Vista, or Windows7. For example, you can set an SWR threshold to trigger an alarm and trip a relay to shut down an amplifier. It can also function as a modulation scope or a spectrum analyzer. The Help File on the WaveNode website has a complete list of functions and operating instructions.
High Visibility Display
There are several formats for displaying RF power measurements in real time on a computer monitor. Figure 3 shows the main screen with four meters arranged side-by-side, one for each possible sensor. Each meter has two pairs of vertical bar graphs showing (1) the peak and average forward power and (2) the peak and average reflected power. There are also digital readouts of the SWR, forward power, and reflected power. A pie chart below each graph shows the proportions of forward and reflected power. Screen text is displayed in a large, bold font, and a high contrast color scheme is used.
Figure 3. WaveNode Main Screen (www.wavenode.com)
You can increase the size of any meter by clicking on it with a mouse, which creates a separate window. Then click twice on the meter to enlarge the image as shown in Figure 4. On a typical 22" screen at 120 DPI the meter is 8.2" high, and the heights of the digital readouts for power and SWR are 0.4' and 0.5" respectively.
Figure 4. Meter #1 shown reduced in size. (www.wavenode.com)
An auxiliary screen makes it possible to monitor power supply voltage, current, and the accumulated Amp-Hours of DC current.
Two types of audio output are available using the software—voice announcements and tones. At any time you can call up a voice announcement of the power, SWR, or SWR protection events (when SWR protection has been tripped or reset). Also, you can tune for maximum power or minimum SWR guided by the pitch of an audible tone. The controls are all single-stroke key presses.
Software for digital communication can be used on the same computer with the WaveNode interface. However, the WaveNode audio output can not be used if another application, such as a digital mode program, uses the PC sound card.
Other Digital Functions
• Both models provide oscilloscope and spectrum analysis of the RF modulation to check for IM and "splatter" outside the intended frequency range. The controls for these powerful features are remarkably easy to use.
• There is a screen for graphing SWR vs. frequency.
• Two sensors can be compared in real time to measure the gain and linearity of an amplifier.
• Both units can control Yaesu Series rotators.
• Both models can also be used to monitor a ham station that is remotely operated via the Internet.
WaveNode Station Monitors are sophisticated monitoring systems. For vision-impaired hams, these features stand out:
• large display RF power and SWR meters designed for readability
• high-brightness LED bar graphs on the WN-2d unit
• voice announcements of RF power, SWR, and SWR protection
• audible tone output to assist tuning for power and SWR
• an alarm and a relay tripped by high SWR
The graphical controls and displays are very well designed for ease of use.
Thanks to Alan Burroughs, AD6MT, of WaveNode for information and for loaning the monitor.
Peter DeNeef, AE7PD, is an Extra Class amateur radio operator in the U.S. This web site has no ads or conflicts of interest.
Email: hamradioandvision "at" gmail "dot" com.
Related Article: Audio SWR Meter in MFJ Automatic Tuners