Elecraft K1

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Why Build Kits?

It is often said that home construction is dying out. That may be true, but in some areas of the hobby there remains a strong desire to build equipment. One such area is that of QRP (low power). Low power operating tends to lend itself to the construction of simple equipment and many have testified to the satisfaction that comes from making contacts with equipment that has been home made. There is a vast pool of amateurs who have learned all the skills needed to build simple equipment, but many of them lack the confidence to pick up a circuit diagram and construct something from scratch. These amateurs are today's novices. For novices, building well designed kits is surely a good way to gain more confidence before "flying solo" with a circuit diagram. But kits are not just for novices. The pleasure of assembling a high quality kit with all of the components to-hand and all the mechanical work done by someone else is something that all amateurs can enjoy.

There is a vast range of kits available these days. They span from very simple station accessories to fully featured HF transceivers. The quality varies just as widely. People have sometimes said to me that kits are expensive (compared to second-hand equipment), lacking in features (compared to what is available in the ready-built market) and have little or no residual value (no one will buy your old kit equipment). Before embarking on this review it is perhaps worth exploring these ideas.

Kits have been with us for nearly as long as amateur radio has existed, but what purpose do they serve? Recently someone said to me at our local radio club that he could not understand why people would pay 100 or more for a low power, single band, CW kit transceiver when they could pick up an old FT101 for not much more. He has a point of course. In general, if you compare functionality and cost, that old FT101 will almost always come out ahead of a kit. But that's missing some of the picture.

Amateur radio is about "self training" - learning by doing. Kits surely offer a readily accessible way to start constructing your own equipment. A charge   sometimes levelled against kits is that, like painting by numbers, there is no real understanding of the art gained during the construction process. That may be true in some (even many) cases - but surely what is gained is familiarity with components, assembly techniques, working methodically - even tidiness (something that has never rubbed off on me!). These skills certainly don't necessarily lead to a better understanding of circuits and circuit design but they surely do lay a foundation from which that higher-level understanding may come. Kits also lend themselves to modification much more than commercial gear; that's a valuable learning process too.

Continuing the comparison with that old FT101 and a kit, people seem to get great satisfaction from building kits. There is nothing quite like using a radio that you have built yourself. I am sure that this accounts for the almost magical results that people get with home-built gear. I think that it 's not really magic, it's just that they are so much more inclined to call that DX station just to see what can be done with something they made themselves.

I build kits (and radios from schematics) because I want small basic equipment for back-packing. I'm prepared to pay a premium for that as I can't afford the medical bills that would result from backpacking with an FT101.

"Of course kits offer poorer performance than "bought" equipment" - this is simply not true.The best kits radios can compete with the best that you can buy. How's it done? Simple; kits don't have to have all of unnecessary bells and whistles that sell the ready-built radio. The bells and whistles often lead to compromises in other areas, kits can concentrate on decent RF performance - and that's what really matters most of the time.

So how come kits cost so much? I'm not sure that they do. Let's look at the economics. A successful kit transceiver will sell maybe 500 units. Yaesu's next HF transceiver is more likely to sell over 100,000. That economy of scale makes a huge difference in the costs that can be achieved. Yaesu's transceiver will be constructed mostly by machine. That will not add much to the overall cost of the product. They will also use cheap surface mount components - your kit will probably use more expensive through-hole parts. The kit will have to be packaged with all its components in little bags, Yaesu's component come in bulk on reels and have very low handling costs. You will build your kit but won't be saving much by doing so. If you think that a kit is a rip-off, try getting all those components together yourself and charge your time at, say 10 per hour, then see how much your home-built gear costs! Don't expect to save money with a kit - you're paying more for a better overall experience (and a more serviceable product!).

Residual value (what you get if you sell something second-hand) is also worth considering. Homebrew gear generally has a very low residual value, as do most kits. Good residual value can make kits seem much more financially attractive - but good residual value generally means that the finished product must not look "home made". The best kits look good when they are finished - which is perhaps why Heathkit radios still command good prices.

Elecraft

A couple of years ago a new company appeared in the kit market. This company is called Elecraft. Based in the USA, they launched an ambitious first product - the K2. This is a fully featured HF transceiver that compares well with the very best ready built gear. It is a complex project, although many first-time constructors have successfully built it. Its fame spread quickly and there are now thousands in everyday use. The K2 is an excellent home station and vacation radio but is perhaps a little large for truly portable operation. Elecraft realised this and last year they announced the K1, a small HF transceiver designed with portable operation in mind. Such is the reputation of Elecraft that the K1 has already sold around 1000 units.

Circuit Description

The K1 is a 2 band CW transceiver. It has a single conversion superheterodyne receiver with an IF of 4.915MHz. The transmitter runs 5 Watts. This sounds rather dull - so why has it been so successful? I believe it is because the design is so cleverly implemented. Let's work through the receiver. The signal entered through a low pass filter (also used on transmit) and then passes through a band pass filter. These filters in common with all of the band-specific components are mounted on a small plug-in circuit board. This sits piggy-back style on the main PCB and allows the users to choose any pair of bands between 80 and 15 metres. Changing boards is easy and for most portable operation, a pair of bands will give adequate flexibility. I chose 20m and 40m - the most popular combination. The signal next passes via a switched attenuator to the first mixer. This is a Gilbert Cell device (NE602). These devices are very popular and are characterised by high gain, low current consumption, and unfortunately rather poor dynamic range. So why have Elecraft chosen them? For good portable equipment, there are compromises to be made. Mixers with good dynamic range tend to have high current consumption. That means bigger batteries or less operating time. The NE602 is cheap, simple and mostly adequate. The oscillator uses a 3MHz VFO with a premix scheme to give the correct frequencies for each band. The VFO is tuned by a high quality 10-turn turn potentiometer and covers approximately 80 KHz (the exact range can be changed by the constructor). The mixer output is at 4.915MHz. IF filtering is achieved with a four-crystal ladder filter. Another NE606 is used as the BFO/product detector mixer, the resulting audio is then fed to an AF preamp and finally and LM380N AF amplifier. An audio derived automatic gain control loop keeps the output constant. The transmitter is very simple with the premix signal fed to another NE602 mixer, a buffer, some filtering and finally a broadband PA consisting of two stages of amplification using bipolar transistors.

Reading this description, I expect you are still thinking that the design is pretty ordinary. But that's because I have missed out Elecraft's clever design. Much of this radio is controlled by a microprocessor and in doing this Elecraft have achieved some amazing facilities. Let's go back to the receiver. The attenuator is switched from the front panel under software control. The operating frequency and band is displayed to a resolution of 100 Hz on an LCD display on the front panel. The display shows three digits and tapping the "display" button causes the display to show the Megahertz, kilohertz and finally decimals of kilohertz. The receiver bandwidth is also under software control. The crystal ladder filter is implemented with varactor diodes instead of fixed capacitors and the control voltage (bandwidth) is selected from the front panel. three different bandwidths are selectable from the front panel and these can be defined by the user. I have mine set at 850Hz, 400HZ and 200Hz. The AGC voltage is also read by the processor and one of the display modes shows bars relating to signal strength. In this mode, the frequency cannot be displayed but the radio detects when you turn the tuning knob and displays the frequency again until you stop tuning - a nice touch!

The transmit/receive switching is all solid state and the delay is user definable under software control. Full break in is easily possible and is silky smooth with no nasty clicks or thumps (and no clattering relays).

The transmitter power control is under software control and the power can be directly set from the front panel. The display reverts to a bar graph showing power output on transmit and when in the "tune" mode, actual power output is displayed. Power can be set between 100mW and just over 5W in 100mW steps.

The radio has a built-in Morse keyer. The speed is under software control and is displayed directly in words per minute on the front panel display. The keyer has two memories each with 90 bytes available - easily enough for most purposes.

The front panel display will also read the battery voltage (and alert you when it is low both by means of a tone and on the display). The receiver has incremental tuning (RIT) as does the transmitter (XIT). There is a menu system accessible from the front panel that allows various other facilities to be customised, for example transmit sidetone frequency and level are adjustable. Since the radio is designed to allow low current portable operation, even the RIT and Attenuator LEDs can be disabled via the menu system to save current (they are replaced by audio tones). Another current saving feature is the use of latching relays throughout. These only consume power whilst changing over.

The transceiver is housed in a very smart looking case, giving a professional finish to your home made radio. The case design is cunning too and each panel can be separately removed for access. The circuit boards all plug together leaving very little wiring to be done to assemble the radio - neat!

There are a number of options available including an internal automatic aerial matching unit, a noise blanker, a stand and, most recently an internal battery pack.

Assembly

I ordered my K1 and 11 days later it arrived. Even the purchasing experience was good with Elecraft acknowledging my order via email and then telling me (a couple of days later) that my kit had been shipped - fast and efficient. The K1 arrives in a small cardboard box. Inside there are various plastic bags with components for each of the three printed circuit boards. The manual runs to about 70 pages and gives extremely detailed instructions on how to build the radio. each instruction has a tick box against it so you can see how you are progressing. The order of construction is logical and each section is tested on completion. In all, I took about 12 hours to assemble my K1. Others have suggested that an inexperienced constructor might take about twice this time, working carefully. The whole process was extremely enjoyable and the instructions were perfect. Anyone who has learned to solder will be able to assemble this radio with confidence. At the end of the assembly, I had no components left over - a good sign. Everything was there and everything fitted properly. The components and printed circuit boards were of the highest quality.

Building kits can seem a bit daunting at first. You pay your money and a box of bits arrives. Half way through you wonder if you have wasted both your time and money. You're on your own. But that's not the case with Elecraft. They have a web-based forum where builders can discuss their kits and get fast advice - often from the people who actually designed the kits. I didn't have to use it but it was nice to know it was there. The alignment was really quite easy and is well described. No sophisticated test equipment is needed. A simple multi-meter is enough. My K1 worked first time!

In Use

I couldn't wait to get on the air. I tuned up my doublet for 40 metres and was quickly making QSOs. My K1 will give about 7 Watts on 40 metres and 5 watts on 20 metres. I was keen to explore the lower power settings too and was excited when an Italian replied to my 100mW CQ call on 20 metres. He was in the QRO league of course - running 300mW! During the WPX CW contest, I worked a string of west coast USA stations on 20 metres and was able to work into the USA on 40m too. The radio is easy to operate and works well. But what of the dynamic range? How did it perform on 40 metres at night? The simple answer is that it performed as I had expected. The attenuator (fixed at 14dB) is absolutely essential on 40m at night. Without it, the band is virtually unusable. With the attenuator in, sanity returns and although there are still audible intermodulation products, they don't cause a real problem. On 20 metres, I have not needed to use the attenuator at all.

G3CWI and K1 on Snowdon.jpg (88072 bytes)

G3CWI and K1 on Snowdon

But all this "shack-bound" operating was not what I bought my K1 for and so as soon as the weekend came. I told my son (Lewis, aged 6) that it was time he climbed Snowdon. The reward for him was a train ride down, for me it was the chance to really use the K1 on a mountain. The radio is very small and 8 "AA" sized batteries will provide adequate power. The K1 works down to below 8 Volts. The whole station (excluding the aerial and mast) fitted into a plastic lunch box. Lewis and I were soon at the summit and I was itching to get on the air. We found a grassy spot and set up the 10 metre mast, strung out the 40 m dipole and away we went. This was not going to be a marathon effort however as 6 year olds don't find CW radio all that interesting so my bargain was just three QSOs and then the train followed by an ice-cream (pity this level of bribery doesn't work with the wife!). The K1 performed perfectly. I was glad of the pre-programmed CQ facilities and before long the three QSOs were in the log and the journey down commenced.

Could do better?

There has yet to be a perfect radio made, and the K1 isn't perfect. There are a number of things that could have been a little better.

bulletI am not convinced that the balance between performance and current consumption of the NE602 mixer is quite right. I would have liked a little better strong-signal performance (even at the expense of some current).
bulletThe manual, while generally excellent, does not list the default settings for each menu option. That would have been nice.
bulletThe RIT/XIT pot needs a centre detent and ideally the frequency display would read the offset when you turn the control (not the absolute frequency).
bulletProvision for some way to illuminate the frequency readout would be useful.
bulletFor general listening, an option to move the VFO range into the sideband section of the band and select a little wider filter bandwidth (even if the shape wasn't too good) would be nice.
bulletAn earth terminal at the rear of the radio would have been nice (for those radials).
bulletAn unused switch on the front panel for user customisation would be good too!

Conclusions

The K1 has fully lived up to my expectations. I'm looking forward to my next trip out with it. It will also make a super vacation radio. Its limited dynamic range rules it out for me as a home station (the K2 will do that!). But out and about, there is nothing to touch it.

It would make a good first project and gives a pleasing piece of equipment that is certain to have a good resale value. You wont want to sell it though!

The basic K1 cost me 215 + 48 VAT and import duty. It is available via the Elecraft website and can be bought by credit card. Overall, I think that the K1 is good value-for-money.

 

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