N5ESE's Version of the K1EL Model K40 CW Keyboard/Keyer
(click on any picture to see larger version)
| NOTE: 'N5FC' is my former call. Portions of this project were constructed while that call was valid, and you may observe references to it. |
I first began using a keyboard (KB) to generate CW about 25 years ago, when (after thousands of hours on the iambic keyer) I finally realized I wasn't ever going to get very good at it. I was always sloppy sending on the paddles for about 15 minutes, after which I would get "pretty" good for about half an hour, then start deteriorating rapidly. Oh, well.
My first keyboard was a homebrew jobbie, designed by the late Harry W5DF (not the current W5DF). It used discrete 4000-series CMOS ICs, operated from a 9V battery, and had a one-character type-ahead buffer. Even with two fingers, I quickly learned I could send nearly flawless CW at 30-35 wpm, and my old cronie brass-pounding buddies all thanked me for it ;-). [By the way, I recently re-acquired the long-lost schematic for that project, thanks to Ted AB8FJ, and may try laying it out in surface mount someday soon].
I gave away my W5DF KB during a 3-year hiatus from ham radio, and went back to the keyer for a few years when I returned. I gradually recollected why I had switched to the keyboard, and began looking for something I could build up myself, and cheaply. I ran across K1EL, and what a find that was! Among other things, K1EL provides keyer and keyboard chips and kits at extremely reasonable prices. I settled on the K20 kit, which included two PIC microcontrollers, a PC board, and supporting components for around $25. Amazing! The K20 has a large type-ahead buffer, and numerous user-configurable memories. Heck, it even has a paddle input, in case you want to use a keyer at the same time (???). It interfaces directly to a standard AT-type PC keyboard (not the PC, just the keyboard). You provide the power (+8 - 18 VDCat less than 250mA), and you're in business with a full-featured CW keyboard, sending sweet CW. Keep in mind that a keyboard, at least in this context, is a sending device... you still copy CW by ear.
I built my K20 board, and installed it inside a brand-new, surplus DELL keyboard, which I picked up at the local Goodwill Industries computerl store for $4. One reason I selected the DELL keyboard was because DELL was making a concerted effort toward "green" PCs, which meant their keyboards would be low-current-draw. In fact, the one I found drew less than 15 mA at 5 V.
The Model K20 PC Board is obsolete now, but the keyboard I built based on that pc board is still in regular use. You can see a picture of the completed KB -here-, and the inside layout -here-.
K1EL replaced the K20 design with the updated Model K40, at a mere $32 per kit. The functionality is enhanced, and the current draw is reduced somewhat, but it's still basically the same machine. I wanted to have another keyboard for portable use, and had recently bought a "mini-keyboard" for $15 [Behavoir Tech BTC Model 9118), with the intentions of building the K40 into it.. The K40 still requires a PS/2 type keyboard, and these type keyboards are gradually going the way of the dinosaur, but if you can find 'em, they're pretty cheap. Anyway, I bought it hoping I could fit the K40 inside it, and sure enough, I could. Here's a picture of the inside of the keyboard with the back cover removed, before any mods.
Construction
You can see the manufacturer's keyboard encoder circuit board at the top left. Also notice the PS/2 cable and a heavy-duty toroidal ferrite core on the cable. We clipped the cable about 6 inches from that core, and trashed it. 6 inches is all we'd need to connect the PS/2 signals to the new K40 board. The area to the right of the manufacturer's board is plenty roomy enough for the K40 pcb, provided that we minmize the height profile by making some component adjustments.
The K40 kit is a breeze to assemble, but you have to use some savvy about kit assembly and parts identification to make sure you get it assembled properly. A good schematic, parts list, and component layout drawing are provided for downloading at the site, in the guise of a user manual. Step-by-step assembly instructions are minimal, so use care and make sure you understand what you're doing before soldering. Because I wanted to minimize the board's height profile, I made a number of parts substititions from my junkbox. For example, I replaced most of the disc capacitors, plus the electrolytic provided with the kit, with surface-mount caps from my junk box. Also, I soldered the two PIC 16F688 microcontrollers directly to the board, instead of using the sockets provided. The piezo speaker was relocated off board, too. Since I intended to wire the K40 directly and internally to the keyboard, I left off the PS/2 style DIN connector. When assembled in this way, the K40 pcb looked like so:
You might notice that there is no regulator (U1) installed on board. In its place, I've installed a 1N5718 schottky protection diode. It was my intention to run the keyboard from a small battery pack consisting of either 3 AA alkaline batteries or 4 AA NiMH batteries. A little research revealed that all of the electronics in both the keyboard and the K40 are capable of operation from 3.5 to 5.5 Volts DC, so the 7805 regulator did little to help in this situation except to boost current consumption by about 200%.
Size of the K40 pc board is roughly 2 x 2 inches, and we managed to keep the height profile to less than 1/4-inch. That allowed us to find a spot inside the keyboard cabinet where the K40 would fit. On one corner, we mounted it on a built-in plastic spacer that happened to have a drilled hole in it that threaded perfectly for a 4-40 screw. On the other three corners, we mounted 4-40 spacers robbed from some SUB-D connectors from some old computer equipment, and epoxied them to the flat surface we had selected on the keyboard assembly.
After drilling a 1/8-inch hole for the sound port, we located the piezo speaker (supplied with the K40) to an area near the three LEDs (which are part of the original keyboard), and super-glued it in place. Here's a detail of that mounting:
After studying the molding on the keyboard case, we drilled holes in the bottom cover along the back and one side, to accommodate the KEY OUT jack, the PADDLE IN jack, and the POWER Jack. Here's a picture from the outside of those three connectors:
My experience has shown me that RF arriving through the key line is sometimes problematic, and to preclude those kinds of problems, we wound the two wires going to the KEY OUT jack several turns through an FT37-43 core, to form a common-mode EMI filter. Here's a detail of that:
The following picture shows the entire assembly, wired, with boards and connectors in place, and gices a pretty good overview of how it all fits together. This is an "inside" view, with the keyboard on the left, and the bottom cover on the right. Notice that the K40 pcb is mounted upside down (component side down).
To spruce things up a bit, and to provide a cheat sheet of key programmable functions, we created labels using Microsoft Word, and printed them onto "sticky-back" paper (commonly called full-size mailing labels). Then we put a sticky-back laminate over the top of the labels to preserve them. You can see the reults in the picture at the top of the page)
When all is said and done, the keyboard makes a pretty smart looking CW KB, and with no PC or bulky cables, takes up only its own footprint at the operating position. It's about 2/3 the size of a full-sized PC keyboard, and will fit easily in my portable kit or suitcase.
Summary
The keyboard manufacturer threw me a little curve, which took me an hour or so to figure out. When I first turned the unit on, some of the function keys (like the Shift-F4 morse practice mode) worked, but most keys were unresponsive. At first, I thought I had a bad keyboard, but then, mainly by accident, I discovered that one of the new "Windows" special function keys is designed to "wake up" the keyboard from "sleep mode". Once I figured that out, all worked jim-dandy. Now, after powering up, I just tap that special key, and all works as advertised.
The K1EL K40 keyboard/keyer is packed with features. Many of them were not implemented in this application. Notable among those is the capability to drive a cheapo LCD display. This would have been a nice feature, especially when you're typing ahead and forget your place or wonder if you've made a typo. But I simply didn't have the clearance to install an LCD display and its attendent wiring. So I'll just have to slow down my hunt-and-peck technique and try to minimize the typing errors. Unfortunately, CW Keyboards don't come with spell checkers HI HI.
The K40 has a first class keyer built in, which can be set to operate in Mode A, mode B, or "Ultimatic". It can also be made to operate as a "Bug", where the dash paddle is strictly manual. One keyer feature not often found, but that I rely on heavily to clean up my sloppy fist, is the "AutoSpace". When turned on, it makes sure the spacing between letters doesn't get rushed, and makes your paddle code sound almost as perfect as the keyboard code. I like to have the paddle hooked up to the keyboard all the time, so I can switch to it on the slightest whim. In fact, you can go back and forth between keyer and keyboard effortlessly, and that's real nice.
The K40 has lotsa memory and a big type-ahead buffer of 200 characters. An LED on the keyboard blinks when you approach the end of the buffer, giving you plenty of time to stop sending. Most of the time you won't use that much buffer, but occasionally I'll QSO someone at 10 wpm, and type ahead and go get another cup of coffee while it's sending. 12 memories (on function keys F1 through F12) can be user-programmed, and those memories are stored in EEPROM, meaning they'll still be there when you power up a week from now.
For contests, the K40 can be programmed to generate serial numbers automatically. Really neat (although I do very little contesting).
One feature I particularly like about the K40 is the beacon-memory mode. I've programmed key F8 to send CQ CQ CQ de N5ESE N5ESE/QRP (twice), then wait 5 seconds before starting again automatically. This way, when the band is dead, I can put the rig on CQ beacon, donn my wireless headphones, and go surf the web until I get a call. Nine times out of ten, I don't have to wait long.
An unexpectedly nice feature about the BTC 9118 mini-keyboard, combined with the K1EL K40, is that it draws only 4 mA (18 mA with sidetone on), making it ideal for a portable keyboard. The manufacturer's packaging had indicated the current draw was 50 mA or less, so it was a very pleasant surpise to see it weigh in at an order of magnitude less.
The K40 keys all my rigs very nicely, including my little hombrew "Altoobs" rig, which uses cathode keying. I can QSO for hours, and everyone thinks I'm a tireless A-1 op. NOT! But let's just keep that little secret between you and me...
73, monty N5ESE
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