Elecraft W1 User Manual
ELECRAFT W1 Power Meter
Assembly and Operating Manual
E740100: Revision D, October 12, 2008
Copyright © 2008, Elecraft; All Rights Reserved
Introduction
The Elecraft W1 is a versatile RF power and SWR meter than can be used with any transmitter from QRP levels to 140 watts
output from 1.8 to 30 MHz. The W1 automatically selects the proper power range of up to 1.4, 14 or 140 watts and indicates
the peak forward power and SWR on built in LEDs. The power and SWR is also available through a connector as RS232
serial data for display on a computer or to control other equipment.
The W1 Power meter is designed to be used as a stand-alone unit that may be powered from a self-contained battery or an
external power source. Optionally, it may be built into existing equipment or an enclosure of your choice. See Assembly
Options on page 3 for more information.
The W1 uses no surface-mount technology, so it’s an ideal project for first-time builders.
Specifications
Size: 5-3/8” x 2-11/16” (13.7 cm x 6.8 cm).
Internal Power: 9V battery.
External Power: 7-14 V (8 V min. recommended).
Current Drain: 10 mA idle, 30 mA with 10 LEDs illuminated.
Power Range; Auto-ranging, 1.4, 14 and 140 watts.
Accuracy: 0.5 dB typical.
Frequency Range: 1.8 to 30 MHz.
Tools Required
You will need the following tools to build this kit:
Fine-tip temperature-controlled ESD-safe soldering station with 700 to 800F tip (370-430C). Recommend a spade
tip no greater than 0.05” (1.3 mm) wide.
IC-grade solder (Kester #44 or equivalent). Small diameter solder (e.g. .031”) is easiest to work with on small
printed circuit boards. DO NOT use acid-core solder, water-soluble flux solder, additional flux or solvents.
Needle-nose pliers.
Diagonal cutters.
Small, #2 Phillips screwdriver.
Small wrench or driver for 4-40 nut.
Digital Multimeter (DMM) with voltage, resistance and diode-checking functions is useful for confirming the value
of components. A DMM with capacitance measurement capability is desirable, but not required.
Desoldering tools and supplies are invaluable. Narrow solder wick or a good vacuum desoldering tool such as the
Soldapullt® model DS017LS are recommended.
A conductive wrist strap and anti-static mat is recommended (see ESD-Sensitive Parts below). Wrist straps and mats
are available at very low cost from Jameco, Mouser, and other electronics suppliers.
Refer to www.elecraft.com for tool sources and solder recommendations.
Parts List
We strongly recommend that you do a complete inventory before beginning assembly. The inventory helps you correctly
identify all the parts to avoid mistakes during assembly.
Elecraft • www.elecraft.com • 831-662-8345
ESD-Sensitive Parts
Some of the parts in this kit are sensitive to damage from electro-static discharge (ESD). Problems caused by ESD damage
may be very difficult to troubleshoot because damaged components may still operate somewhat rather than fail completely.
We strongly recommend you take the following anti-static precautions (listed in order of importance) to avoid trouble:
Leave ESD-sensitive parts in their anti-static packaging until you install them. The packaging may be a special
plastic bag or the component’s leads may be inserted in conductive foam. 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. 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. DO NOT attach a ground
directly to yourself as this poses a serious shock hazard.
Make sure your soldering iron is ESD-safe and has a grounded tip
Use a grounded anti-static mat on your work bench.
Identifying Parts
In some cases the component marking is self-evident. For example, a 1N5711 diode may have “1N5711” stamped on its
body. When the markings are not so obvious, the marks you should find to identify individual components are shown in
parenthesis in the parts list and text. These may be numbers such as “(103)” on capacitors or colors on resistors such as “(brnblk-red)”. Look for the color band sequence starting near one end of the component. Some resistors have dark blue bodies
that make identifying the colors difficult. Use your DMM to verify the value if you aren’t sure. Remember that your DMM
usually will indicate a value close to, but not exactly what is shown due to normal tolerances in the components and the
DMM.
There may be more numbers, letters or color bands on a component than those shown in parenthesis. The additional markings
may change from unit to unit and are not important for identifying the part supplied with the kit.
Reference. Designator Description Qty
Misc. W1 Power Meter Printed Circuit Board 1 E100308
B1 Battery Holder 1 E980074
C1, C2 .001µF (102) Capacitor 2 E530074
C3, C10 .047µF (473) Capacitor 2 E530131
C4, C5, C6, C7, C11, C12, C16, C17 .01µF (103) Capacitor 8 E530130
C8, C9 22µF 25V Electrolytic Capacitor 2 E530012
D1, D2, D3 1N5711 (5711) Diode 3 E560004
D4, D5, D29 1N4148 (4148) Diode 3 E560002
D6, D7, D8, D9, D10, D11, D12, D13, D14, D15, D16, D17,
D18, D19, D20, D21, D22, D23, D24, D25
D26 Round LED, Green 1 E570027
D27 Round LED, Yellow 1 E570028
D28 Round LED, Red 1 E570025
J1, J2 BNC Connector, PC Mount 2 E620020
J3 Stereo Jack, Miniature 1 E620027
J4 Jack, 2.1 mm, 12VDC Power 1 E620026
R1, R2 51Ω 3W Resistor 2 E500178
R3, R4, R5 332K, 1% (org-org-red-org) 1/4W Resistor 3 E500254
R6, R7, R9 49.9K 1% (yel-wht-wht-red) 1/4W Resistor 3 E500255
R8 47K (yel-vio-org)1/4W Resistor 1 E500067
R10 240 Ω (red-yel-brn) 1/4W Resistor 1 E500281
R11 2K (red-blk-red) 1/4W Resistor 1 E500280
R12, R13, R20 24.9K 1% (red-yel-wht-red)1/4W Resistor 3 E500120
R14 1K (brn-blk-red) 1/4W Resistor 1 E500013
Rectangular LED, Red 20 E570026
Part
Number
2
Reference. Designator Description Qty
R15, R21 100K (brn-blk-yel) 1/4W Resistor 2 E500006
R16 10k (brn-blk-org) 1/4W Resistor 1 E500015
R17 5k (502) Trimmer Potentiometer 1 E520009
R18, R22 22K (red-red-org) 1/4W Resistor 2 E500090
R19 3K (org-blk-red) 1/4W Resistor 1 E500169
RP1, RP2 2K (202P) Resistor pack 2 E510031
2N7000 Transistor
Q1, Q2, Q3, Q4, Q5, Q6
Q7 2N3904 Transistor 1 E580017
SW1 Switch 1 E640009
T1 Binocular Core 1 E690011
U1, U2
U3
U4
X1 Ceramic Resonator, 4MHz (4.00) 1 E660001
Hardware Screw, Pan Head, Black Machine, 4-40 4 E700008
Hardware Lock Washer, Internal Tooth, #4 4 E700010
Hardware Nut, #4-40 4 E700011
Misc. I.C. Socket, 28 Pin 1 E620011
Misc. #28 Enameled Wire for T1 72” E760003
Misc.
Misc. Rubber Foot 4 E700024
i
ESD Sensitive. Take precautions when
handling (see ESD-Sensitive Parts above.)
LMC6482 Integrated Circuit
i
ESD Sensitive. Take precautions when
handling (see ESD-Sensitive Parts above.)
LM78L05 Integrated Circuit
Microcontroller PIC16F876A, Programmed
i
ESD Sensitive. Take precautions when
handling (see ESD-Sensitive Parts above.)
1
#18 Teflon®
Insulated Wire for T1
6 E580002
2 E600011
1 E600029
1 E610022
6” E760021
Part
Number
Assembly Options
The W1 is designed to operate as a stand-alone unit without an enclosure. Several options are provided in case you want to
build the unit into an enclosure or existing equipment:
1. Your W1 is provided with BNC connectors that mount parallel to the board. Normally these connectors will be
mounted on the top (silk screened) side of the board so that the board rests flat on the supplied rubber feet attached
to the bottom. However if you are building the unit to place in an enclosure of your choice, you may elect to mount
the BNC connectors on the bottom of the board. Also, you may purchase right-angle BNC connectors that also may
be mounted either on the top or the bottom of the board. Suitable connectors are available from Digi-Key
(www.digikey.com
, part number A32246-ND) or Mouser Electronics® (www.mouser.com, part number 571-
2272226).
2. Mounting holes are provided in the board that you may use with your own #4 hardware and spacers as desired
instead of using the rubber feet.
3. If you are going to power your W1 using an external source only, you may choose not to install the battery holder.
4. Transformer T1 may be obtained pre-wound from an Elecraft-approved source. See www.elecraft.com
1
Teflon is a registered trademark of du Pont de Nemours and Company.
3
®
for details.
Assembly Procedure
The finished Power Meter is shown in Figure 1. We recommend you follow the assembly procedure below and refer to this
figure as needed.
Figure 1. Assembled W1 Power Meter.
i
Use adequate ventilation when soldering; avoid inhaling smoke or fumes. Always wash your hands after
handling solder, as lead residue is highly toxic.
When applying solder, use the minimum amount required to surround the component lead and make good contact with its
printed-circuit pad. You don't need a "fillet" (build-up) of solder. This will avoid unwanted solder bridges and any need to
clean the PC boards.
The solder must flow onto both the component lead and its PC board pad. To ensure that both will be heated at the same time,
the tip of the iron should contact both the component lead and the PC board pad before solder is applied.
Solder joints should be clean and shiny. If a joint appears dull or has fine cracks, it is probably cold. Cold solder joints should
be cleaned and re-soldered. First, use solder wick (desoldering braid) to remove the old solder. Then apply fresh solder. If
you have many cold solder joints, it probably indicates that your soldering iron temperature is too low, or that the tip or
solder itself is defective.
leads flush on the bottom. If you position the board so the legends are right side up, you can work clockwise around the board
starting with R10 near the space for R2 at the top (Resistors R1 and R2 will be installed later). Save one of the clipped
resistor leads to use for a ground test point later.
Install the fixed resistors listed below. Position each resistor against the board within the outline, solder and trim the
__ R10, 240Ω (red-yel-brn)
__ R5, 332K 1% (org-org-red-org)
Continued on next page.
__ R11, 2K (red-blk-red)
__ R9, 49.9K 1% (yel-wht-wht-red)
4
__ R20, 24.9K 1% (red-yel-wht-red)
__ R18, 22K (red-red-org)
__ R22, 22K (red-red-org)
__ R21, 100K (brn-blk-yel)
__ R6, 49.9K 1% (yel-wht-wht-red)
__ R12, 24.9K 1% (red-yel-wht-red)
__ R7, 49.9K 1% (yel-wht-wht-red)
__ R4, 332K 1% (org-org-red-org) Be careful not to fill the solder pad for D2.
Install the resistor packs (RP) near the top center of the board. The numbers indicating the value shown below are
normally the last of a long series of letters and digits. Orient each resistor pack so the grey dot near one end is closest to the
square solder pad. Be sure the packs are positioned vertically with respect to the board and that all the pins are soldered.
__ RP1, (202P)
Locate the six small glass diodes. If you haven’t done so already, sort them by type. Use a strong magnifier, if
necessary, to identify the diodes by the lettering on their bodies. There are three type 1N5711 and three type 1N4148.
Frequently the “1N” part of the type number is not shown on the diode and the remaining numbers and letters may be broken
into two lines.
Install the diodes as follows. The black end of the diode body must be aligned with the stripe on the silk screened
outline on the board and closest to the square solder pad.
__ RP2, (202P)
__ R16, 10K (brn-blk-org)
__ R14, 1K (brn-blk-red)
__ R15, 100K (brn-blk-yel)
__ R8, 47K (yel-vio-org)
__ R19, 3K (org-blk-red)
__ R13, 24.9K 1% (red-yel-wht-red)
__ R3, 332K 1% (org-org-red-org)
__ D2, 1N5711 (5711) near R4
__ D3, 1N5711 (5711)
__ D5, 1N4148 (4148)
Install the capacitors listed below, working from left to right across the board:
__ C2, .001µF (102) near D2
__ C3, .047µF (473) next to C2
__ C5, .01µF (103)
__ C6, .01µF (103)
__ C17, .01µF (103)
__ C11, .01µF (103) lower edge below D29
i
Once soldered, the socket for U4 will be difficult to remove from the board without destroying it. Before
soldering, check to be certain it is positioned correctly.
is aligned with the notch in the silk-screened outline on the board at the end closest to R16. While holding the socket
against the board, wet your soldering iron with a small drop of solder and touch it to one pin at each end of the socket to hold
it in place, then inspect the socket carefully to ensure that the shoulders of all the pins are against the top of the board. If
needed, reheat the soldered pins while pressing the down on the socket.
the pins you temporarily soldered in the preceding step.
Align the socket with the outline for U4 just below resistor packs RP1 and RP2. Be sure the notched end of the socket
When you are satisfied that the socket is seated against the top of the board, solder all 28 pins. Be sure to properly solder
__ D1, 1N5711 (5711)
__ D4, 1N4148 (4148) near R22
__ D29, 1N4148 (4148)
__ C1, .001µF (102) below C2 near R4
__ C4, .01µF (103)
__ C7, .01µF (103)
__ C12, .01µF (103)
__ C10, .047µF (473) near RP2
__ C16, .01µF (103)
Install ceramic resonator X1 (4.00) near the socket for U4. It looks like a large molded capacitor but has three pins. It
may be installed oriented either way.
Bend the clipped resistor lead you saved earlier into a “U” that fits into the solder pads at each end of the ground test
point below R21. The solder pads have a line between them and a
with the loop high enough above the board to easily clip a test probe lead onto it.
symbol next to the line. Solder the lead into the pads
5
Loading...