The Elecraft W1 Wattmeter
Yes ... yet another Elecraft kit. This one is small -- build it in two evenings -- if you go really slow. It is a really neat little auto-ranging wattmeter/SWR indicator that is highly portable. I wanted one as an accessory for my KX1 and K2 because I bought a BuddiPole antenna, and need some way to tune it for minimum VSWR. Usual caveats apply, I know Wayne and Eric, and I am their customer, and I have no financial interest in Elecraft [although I think I wish I did!], and the Elecraft website does a much better job of describing it than I do here.
The W1 itself is just a circuit board. You get to mount it where and as you wish. W8FGU, a firefighter in the Detroit MI area, has come up with a really cool enclosure for the W1. It is flexible, there are two models allowing the BNC RF connectors to emerge from the sides [as mine do], or from the back. He has an optional adjustable tilt stand for it as well, and his web site does a much better job at describing it than this one does. Caveats -- Dave is a friend, a good one, and I helped him in beta testing his mechanical layouts and assembly. We have some other interests in common. However, I am not financially connected, and he gave me my final enclosure free. Thanks Dave.
The wattmeter has three ranges: 0-1.4W [good for a KX1 running on AA rechargeables], 0 - 14W [great for a stock K2, and 0 - 140W for any 100W or so rig, and it automatically chooses the proper range, indicating which one on one of the three LEDs about half way down the left edge. They are Green [1.4W], Yellow [14W], and Red [140W]. It has an on-board 9V battery, and can also be powered from a 12V source via a coaxial power connector on the left side just below the range LEDs.
As you might suspect, Elecraft provides remote reading and control software for Windows computers that allow you to control the W1 and monitor the display on your computer. The connector for this is just below the external power connector and is a standard stereo mini-plug for Gnd, TX-data, and RX-data.
The kit itself comprises a single circuit board, a bag of parts and hardware, and an 8-page assembly and instruction manual. The manual follows the standard Elecraft format, and for me at least, assembly was uneventful. All of the K2 soldering provisions apply to the W1 of course. I took two afternoons to assemble mine -- around 6 hours total. Keep in mind, I don't work fast on Elecraft kits. There is one of the "dreaded toroids," and it is a binocular core visible just under the SWR indicator LEDs. It has four "windings," however two of them are simply wires straight through the holes, and the other two are only 11 turns. Calibration requires nothing more than a DMM and you set a voltage at a test point with a potentiometer.
The W8FGU Enclosure
The W1 from Elecraft is a self-contained bare circuit board, and can thus be incorporated into a variety of installations. For me, with my K2 and/or KX1 in field situations, I wanted some sort of small enclosure rugged enough to protect the W1 that was lightweight. Enter Dave, W8FGU who I had met via email earlier exchanging addresses of some deployed troops we were sending packages to. Dave has designed exactly what I wanted -- a clear, lightweight box fabricated from clear polycarbonate. It will accommodate the entire W1, provides access to all the connectors, and includes a push-button on-off switch. The polycarbonate material is scratch resistant, you can see the circuit board inside which looks kind of cool, and the whole thing, with 9V battery, weighs 250 grams [~9 oz]. Dave has two models. The one in my picture has the BNC RF connections out the sides, using the BNC connectors supplied by Elecraft. You can also obtain board-mount BNC's that will exit the back of the enclosure, and Dave has a model for that also. I can't imagine how things could have worked out better for me.
The enclosure comes in two pieces, one of which mounts the W1 circuit board on three stand-offs, and the other completes the box. He uses the same little "3D blocks" that the K2 uses to assemble the case. As with the K2, when you assemble the W1 enclosure, leave the pairs of screws on the blocks a little loose, tighten the single screws, and then tighten the pairs. This will align everything perfectly. I discovered after I had it all built that a double-male BNC adapter will couple the output of my KX1 directly into the input connector of the W1 while both rest solidly on the table. This puts the W1 immediately to the right of the KX1 where it is easy to read, and I got rid of a jumper cable!
Dave has a tilt stand for the enclosure, also fabricated from clear polycarbonate, and rather ingeniously attached with velcro, allowing easy adjustment of viewing angle. I've made up two short jumpers from RG-174 lightweight, small-diameter, flexible 50 ohm coax. It is very flexible, and keeps the heavier RG-58 on my BuddiPole from dragging the wattmeter around. I use the second jumper with my K2.
The W1 and Dave's enclosure makes a really neat addition to my field radios. I generally use the KX1 in outdoor locations for casual QSO's when I just want to be outside running QRP. I use the K2 more for QRP contests, such as the Flight of the Bumblebees or the Spartan Sprint.
I apologize for the lack of good photo quality. I am not a photographer [you can tell that!], I am color-blind, and taking pictures of transparent objects is a challenge.
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