ELECRAFT
W2 WATTMETER
OWNER’S MANUAL
Revision D3, December 7, 2016
E740144
Copyright © 2016, Elecraft, Inc.
All Rights Reserved
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Contents
Introduction ............................................................................................................................................... 3
Customer Service and Support ................................................................................................................. 3
Technical Assistance ....................................................................................................................................... 3
Repair / Alignment Service ............................................................................................................................. 3
Specifications ............................................................................................................................................ 4
Display Unit ........................................................................................................................................................ 4
Directional Couplers (Sensors) ........................................................................................................................... 4
Operation .................................................................................................................................................. 5
Front Panel .......................................................................................................................................................... 5
Rear Panel ........................................................................................................................................................... 6
Directional Coupler (Sensor) .............................................................................................................................. 7
Computer Interface .............................................................................................................................................. 7
Firmware Updates ........................................................................................................................................... 7
SWR Alarm Function ...................................................................................................................................... 8
Kit Assembly ............................................................................................................................................ 8
Preventing Electrostatic Discharge Damage ....................................................................................................... 8
Tools Required .................................................................................................................................................... 9
Assembly Procedure ............................................................................................................................................ 9
Display Unit Assembly ................................................................................................................................... 9
Directional Coupler ....................................................................................................................................... 16
Appendix A Parts List ............................................................................................................................ 17
W2 Circuit Boards............................................................................................................................................. 17
Enclosure ........................................................................................................................................................... 17
W2 Hardware (E850356) .................................................................................................................................. 18
Cables ................................................................................................................................................................ 19
Sensors .............................................................................................................................................................. 19
Appendix B – Schematic Diagrams ........................................................................................................ 20
Appendix C – Power On Modification ................................................................................................... 26
Important Operating Notes for Modified Units ................................................................................................. 26
Installing the Jumper ......................................................................................................................................... 26
Elecraft manuals with color images may be downloaded from
www.elecraft.com.
Introduction
The Elecraft W2 is a versatile, auto-ranging RF power and SWR meter that utilizes remote sensing. Up to two
remote sensors can be attached, with various power and frequency ranges available (see Sensors, page 19).
Sensors use standard CAT5 shielded or unshielded cables.
The W2 includes adjustable, high-brightness LED bargraphs for both forward power and SWR. These allow you
to keep track of transmitter or amplifier performance at a glance, even in low lighting or across a large room.
The power bargraph's full scale ranges are 2, 20, 200, and 2000 watts, with either manual or automatic range
selection or peak- hold capability.
A PC-compatible serial interface is included, allowing easy firmware upgrading via the internet, as well as
configuration of the W2's advanced features. Your W2 includes an interface cable for connection to our
computer’s USB port or RS232 port, depending upon which cable was ordered with the W2 (see pg 19).
Software applications can use the serial interface to accurately read forward power, reverse power, and SWR
from both sensors. This is ideal for remote control as well as customized meter displays.
Also provided is a general purpose alarm output (open-drain) and amplifier keying input/output jacks. The latter
can be used to interrupt amplifier keying on power or SWR alarm conditions.
Subsequent sections provide full specifications, operating information, and assembly instructions for building
the no-soldering kit version of the W2.
Customer Service and Support
Technical Assistance
You can send e-mail to support@elecraft.com and we will respond quickly - typically the same day Monday
through Friday. Telephone assistance is available from 9 A.M. to 5 P.M. Pacific time (weekdays only) at
831-763-4211. Please use e-mail rather than calling when possible since this gives us a written record of the
details of your problem and allows us to handle a larger number of requests each day.
Repair / Alignment Service (We want to make sure everyone succeeds!)
If necessary, you may return your Elecraft product to us for repair or alignment. (Note: We offer unlimited email
and phone support to get your kit running, so please try that route first as we can usually help you find the
problem quickly.)
IMPORTANT: You must contact Elecraft before mailing your product to obtain authorization for the
return, what address to ship it to and current information on repair fees and turnaround times. (Frequently we
can determine the cause of your problem and save you the trouble of shipping it back to us.) Our repair location
is different from our factory location. We will give you the address to ship your kit to at the time of repair
authorization. Packages shipped to Elecraft without authorization will incur an additional shipping charge for
reshipment to our repair depot.
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Specifications
Elecraft's 1-Year Limited Warranty
This warranty is effective as of the date of first consumer purchase (or if shipped from factory, date product is shipped
to customer). It covers both our kits and fully assembled products. For kits, before requesting warranty service, you
should fully complete the assembly, carefully following all instructions in the manual.
Who is covered: This warranty covers the original owner of the Elecraft product as disclosed to Elecraft at the time of
order. Elecraft products transferred by the purchaser to a third party, either by sale, gift or other method, who is not
disclosed to Elecraft at the time of original order, are not covered by this warranty. If the Elecraft product is being
bought indirectly for a third party, the third party's name and address must be provided to Elecraft at time of order to
insure warranty coverage.
What is covered: During the first year after date of purchase, Elecraft will replace defective or missing parts free of
charge (post-paid). We will also correct any malfunction to kits or assembled units caused by defective parts and
materials. Purchaser pays inbound shipping to Elecraft for warranty repair, Elecraft will pay shipping to return the
repaired equipment to you by UPS ground service or equivalent to the continental USA and Canada. Alaska, Hawaii
and outside U.S. and Canada actual return shipping cost paid by owner.
What is not covered: This warranty does not cover correction of kit assembly errors. It also does not cover
misalignment; repair of damage caused by misuse, negligence, or builder modifications; or any performance
malfunctions involving non-Elecraft accessory equipment. The use of acid-core solder, water-soluble flux solder, or any
corrosive or conductive flux or solvent will void this warranty in its entirety. Also not covered is reimbursement for loss
of use, inconvenience, customer assembly or alignment time, or cost of unauthorized service.
Limitation of incidental or consequential damages: This warranty does not extend to non-Elecraft equipment or
components used in conjunction with our products. Any such repair or replacement is the responsibility of the customer.
Elecraft will not be liable for any special, indirect, incidental or consequential damages, incl uding but not limited to any
loss of business or profits.
Display Unit
Size (H x W x D) 1.8" x 6.1" x 4.5" (4.6 cm x 15.5 cm x 11.4 cm), not including connectors.
5.1” (13 cm) deep including connectors, LEDs, rear panel brightness control.
Weight 11.7 oz. (0.33 kg)
Supply voltage 9-16 VDC maximum (10-15 VDC recommended)
Current drain 50 mA idle, 650 mA max, 300 mA typical
Directional Couplers (Sensors)1
Size (H x W x D) 2.5" x 2.3" x 5.0" (6.4 cm x 5.8 cm x 12.7 cm), not including connectors.
Weight 7.5 oz. (0.21 kg) typical
Power Range: (200W Sensor) 0-2W, 0-20W, 0-200W, Auto
(2 KW sensor) 0-20W, 0-200W, 0-2000W, Auto
Accuracy: +/- 0.5 dB typical
Frequency Range: (HF Sensors) 1.8 - 54 MHz
(VHF Sensors) 144 - 450 MHz
Sensor Cable: 5’6” (168 cm) 8-conductor Ethernet (CAT 5) with RJ45 connectors.
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One Sensor is required. Two may be connected to the display unit at the same time.
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Operation
Typically the W2 is inserted between the transmitter and an antenna tuner, if one is used. The W2 then displays
the SWR presented to the transmitter. If the W2 is inserted between the antenna tuner and antenna, it will show
the antenna's unmatched SWR. The power reading may be less accurate when the unmatched SWR is high.
The purpose and operation of each control and indicator on the front panel is described below. On the next page
the rear panel is shown with descriptions of the cable connections and functions of each connector and control.
Front Panel
IMPORTANT NOTES:
1. An automated power-on test cycles all of the front panel LEDs on and off when the POWER button is
pressed. Also, the PTT RY (see Note 3 on the next page) cycles; you can hear it click in a quiet
environment.
2. If the Alarm function is set, all the front panel LEDs will flash if the SWR exceeds 3:1 until you reset the
W2 by pressing either the SENSOR or the RANGE button. See SWR Alarm Function on page 8.
3. The SENSOR, RANGE and PK HOLD settings you select are automatically reinstated after the power
has been turned off.
4. The power display is not affected by the SWR.
5. If two sensors are connected, the W2 can be made to search for the sensor receiving RF. Hold the
SENSOR switch until the S1 and S2 LEDs alternately flash, indicating the W2 is searching. When RF is
applied the active sensor LED will light steady. When RF is removed, the search operation will resume.
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Rear Panel
REAR PANEL CONNECTOR NOTES:
1. A power cable is provided with your W2 with a mating connector for the W2 at one end
and tinned leads for connecting to a power supply at the other end. An RCA plug is also
supplied that you may connect to use the 12VDC accessory output on the back panel of
the K3. Normally you must push the power ON/OFF button to start the W2 after 12VDC is
applied. If you’d like the W2 to run on automatically when power is applied, a simple mod
is required to add a jumper inside the unit. This modification is described in Appendix C of
this manual.
2. Remote Signaling Connector: Provides an alarm output, dropping from +5V to ground
when the SWR exceeds 3:1 (see note 3 below) on the connector ring. Connector tip is a
logic (0-5V) input provided for possible future use.
3. Remote PTT Control: Relay switched loop-through provided to disable a transmitter or
exciter for high SWR protection if the SWR Alarm is set (see SWR Alarm Function on
page 8.
4. PC Data (Optional): Provides an RS232 data interface that may be used to connect the
W2 to a personal computer. See Computer Interface on page 7 and Appendix B for
details.
5. Sensor 1 and 2: A suitable cable is provided with each Sensor unit to connect it to the
display.
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Directional Coupler (Sensor)
A directional coupler is used to measure RF power and standing wave ratio (SWR). A typical directional coupler
is shown below. At least one sensor must be connected to the W2.
Computer Interface
The computer interface provides access to advanced functions controlled through your personal computer (PC).
A suitable interface cable is included to connect your W2 to your computer through a USB or RS232 port,
depending upon the cable you chose when ordering your W2. The W2 Utility program for your computer may
be downloaded free from www.elecraft.com.
Firmware Updates
From time to time, updated and improved firmware may become available for the W2. The latest firmware may
be downloaded from Elecraft and installed using the optional PC interface and the W2 Utility program. Updated
program files may be obtained in two ways. You can check the box in the W2 Utility that says “Copy new files
from Elecraft into local folder”. This will download the latest production released firmware. Optionally, you can
download the new file from the Elecraft web site manually and place it in a local folder, then browse for it
within the W2 utility. This is the way to access the latest Beta firmware available from Elecraft.
A new firmware load is initiated by turning the W2 off, then holding the SENSOR button depressed while
pressing POWER to turn the W2 on. The green 1 LED on the power bar graph will blink indicating the W2 is
ready for new firmware.
When you start loading new firmware, the green 1 LED on the power bar graph will turn off and the yellow 2W
LED will start flashing as new data is received. If the 2W LED stays on but doesn’t flash, data is not being
received by the W2.
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SWR Alarm Function
If set, the SWR Alarm will cause all the LEDs to flash in unison if the SWR exceeds 3:1 and triggers the relay
that opens the circuit between the center pins of the PTT RY phono connectors.
You may set the trip point for the SWR Alarm from 1.1:1 to 5.0:1. Sending the W2 a “[” lowers the trip point,
and “]” raises the trip point in 0.1 steps. Note the decimal point is implied in the serial response, i.e. “[25;”
means the trip point was lowered to an SWR of 2.5:1 and “]39” means the trip point was raised to 3.9:1.
Send an ASCII character a to the W2 to toggle the alarm on or off. This may be done using the W2 Utility
program Command Tester screen. The W2 will respond with a1; indicating the alarm is set or a0; indicating the
alarm is disabled. If an alarm occurs, reset the W2 by pressing either the SENSOR or RANGE buttons.
Kit Assembly
Preventing Electrostatic Discharge Damage
Sensitive components in your W2 are may be damaged by Electrostatic Discharge (ESD) in any location or
climate unless you take specific steps to prevent such damage. Many components can be damaged by static
discharges of only a few volts: far too little for you to notice.
ESD damage may not be apparent at first. The damaged components may not fail completely. Instead, the
damage may result in below-normal performance for an extended period of time before you experience a total
failure.
We strongly recommend you take the following anti-static precautions (listed in order of importance) to ensure
there is no voltage difference between the components and any object that touches them:
Leave ESD-sensitive parts in their anti-static packaging until you install them. The packaging may be a
special plastic bag that allow static charges to flow harmlessly over their surface, or the component’s
leads may be inserted in conductive foam that keep them at the same potential. Parts which are
especially ESD-sensitive are identified in the parts list and in the assembly procedures.
Wear a conductive wrist strap with a series 1-megohm resistor that will constantly drain off any static
charge that accumulates on your body. If you do not have a wrist strap, touch a ground briefly before
touching any sensitive parts to discharge your body. Do this frequently while you are working. You can
collect a destructive static charge on your body just sitting at the work bench.
WARNING
DO NOT attach a ground directly to yourself without a current-limiting resistor as this poses a
serious shock hazard. A wrist strap must include a 1-megohm resistor to limit the current flow. If
you choose to touch an unpainted, metal ground to discharge yourself, do it only when you are
not touching any live circuits with any part of your body.
Use a grounded anti-static mat on your work bench.
If you choose to use a soldering iron to work on your W2 for any reason, be sure your iron has an ESD-
safe grounded tip tied to the same common ground used by your mat or wrist strap.
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