High Visibility RF Wattmeter
and SWR Bridge
This article is for vision-impaired hams interested in the Elecraft W2 HF/VHF/UHF Wattmeter and SWR Bridge. This instrument uses two adjustable, high-brightness LED bargraphs for a high visibility display of forward power and SWR readings. It also includes an interface for viewing the bargraphs on a personal computer screen
Wattmeter and SWR Bridge
The W2 can be used as a standalone meter. It is compact, measuring 1.5 x 6 x 4.5 inches. Judging from photos, the LED power and SWR bargraphs are approximately 3.25 inches and 2.6 inches long, respectively.
The full-scale range of the power bargraph can be set manually or automatically, and there is a peak-hold option.
Three different remote sensors are available. For 1.8 - 54 MHz: 0.1 - 200 Watts and 1 - 2000 Watts. For 144 - 450 MHz: 0.1 - 200 Watts. Up to two sensors can be connected to the W2 and selected via front panel switches.
The W2 also has options to sound an alarm and trip an amplifier keying cutout relay at high SWR.
W2 Interface Program
For a larger readout, free computer interface software is available from Elecraft. It displays digital readouts and bargraphs of the SWR and power on a personal computer screen where they can be magnified (Figure 1). Also, the digital readouts are more precise than the bargraphs on the instrument.
Figure 1. W2 Interface Program window (actual size).
A serial interface built into the W2 allows you to use either an RS-232 connection or a USB port on a computer. The serial connection can also be used to configure the W2 and update the firmware.
Despite its small size, the Elecraft W2 RF Wattmeter and SWR Bridge has three features that may be useful to hams with impaired vision:
• Adjustable, high-brightness LED bargraphs
• Option of using a computer display plus magnification
• Circuits to trigger an alarm and automatically protect
an amplifier if the SWR is high.
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.
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