Friday, 12 October 2012

Elecraft K1

I was delighted to be asked to build an Elecraft K1 on behalf of a fellow ham a few Month's ago.

The K1 kit had arrived within a few days of ordering direct from the USA. The kit came with a very comprehensive owners manual / builders guide. The K1 was ordered with a 2 band filter module (40/20), LCD back light kit and KAT1 auto ATU.

I was expecting a very high quality kit, and I wasn't disappointed!

First of all, the filter board was constructed. All went together fine, the instructions were very clear indeed.

Next came the front panel. The front panel is the main operations centre, it houses the main processor which controls of all the rig's functions. Components are fitted both to the front and back of the board. Again, the construction was very simple.

The instructions were really good. The front panel LCD backlight kit was also added at this time, it is much easier to do it this way than 'retro fitting' it I am reliably informed from multiple sources!

The main board is constructed last of all, this board contains the receive and transmit circuitry, the receive portion mostly towards the front of the board, whilst the transmit portion is mostly at the back. The RX and TX sections are built and tested in turn.

Left - the K1 main board with receive portion complete just after initial 'smoke test'. Luckily there was no smoke! The board fired up first time without problem and all the voltages checked out OK. The instruction book gives lots of testing opportunities, first of all you do resistance checks to make sure than there aren't any solder bridges etc.

Once you are happy with the resistance checks, you then go on to the voltage checks with power applied. Whilst in theory you could just build the whole K1 and do 'all up' testing, building and testing in small bits gives you confidence that you are doing everything right. It's a great feeling when all checks out OK.

The TX portion of the rig went together really well, the hardest part being the winding of the little transformers. I found it a bit tricky to get them to sit and look neat, but I got there in the end and I'm happy with the result.

The alignment of the rig is pretty simple, first you tweak the inductors on RX before completing the TX build, then after TX build you tweak them again on transmit.

I used the sound card on my laptop to set the BFO offset, although initially I had just done it by ear and the computer confirmed that I had got it pretty close. I found it quite amazing that I was using signals from the US to align the rig - 20m was very lively at the time, W1AW kindly confirmed calibration of the VFO readout on 14.0475 MHz :-)

 There are a few components fitted on the underneath side of the main PCB, I guess that Elecraft ran out of space to put them on the top. The rig uses all through-hole components, there are no SMDs used anywhere in the rig. The components all lie flat on the board too, this is not something I'm used to, the kits I've built recently have all used resistors and diodes in a vertical fashion, I use vertical mounting for my Manhattan rigs too, it just saves so much space.

I think Elecraft made a good decision spacing the board out the way they did, it makes construction easy, especially as all the footprints for the similar components are the same, this makes pre-forming the leads a piece of cake - well done Elecraft! (Note that some component locations are intentionally unused - I haven't missed them off by error!)

I think the assembled rig looks very nice, it certainly doesn't look as though somebody has put it together in an attic in Yorkshire! (yes, it was assembled in an attic in Yorkshire!)

There is a lot of work involved building a K1 - it has taken me a number of weeks to put this one together, but I have been doing a short session at a time, say 1 to 2 hours. There are no really hard bits to the construction, there is just a lot of it! The board solders extremely nicely, you can tell that it is a good quality board. I am very impressed by the overall quality of the kit, there is no wonder that Elecraft kits fetch good money second hand.

I'd definitely recommend the K1 kit and I haven't even tried it out on air yet! I would say that it's the best kit building experience I ever had, it's so nice when the instructions are so confidence inspiring and everything is explained in detail.

I have yet to add the KAT1 ATU board to the K1 - the board is fully populated, but I want to give the K1 a thorough try out first without the ATU to make sure everything is working as it should. I hope to try out the K1 this weekend. Once I'm happy everything is OK with the K1, I'll plumb in the ATU. I have never had the luxury of using an auto ATU, so it will be a new experience for me.

The K1 goes back to it's owner at the end of October - I'll be sad to see it go, but I'm very proud of my work. Hopefully I'll get to build somebody else' Elecraft kit in the not too distant future! Any offers? :-)

Hi Mite 17

Well, hasn't time flown by! I can't believe that we are already well in to October.

Back in August I started to build a HiMite 17, using my usual Manhattan style construction technique.

I got the circuit almost working but have since put the project on hold. I hope to get the project finished in the not too distant future.

I used crystals supplied by Graham G3MFJ at G-QRP club sales. Graham has just started stocking 18.086 MHz crystals, this now being the preferred frequency for QRP CW on 17m. I followed the schematic for the HiMite 17 devised by Dave Benson, K1SWL. Dave uses inductors in series with the VXO crystal to pull it down a bit as the crystals originally used were cut for 18.096MHz. I also used an inductor so my rig operates at slightly lower than 18.086MHz.

The frequency of the rig can be 'wiggled' by the use of 2 potentiometers to change the RX and TX frequency a little bit.

I seem to have lost my supply of violet LEDs, so I used a pink one instead - isn't it pretty? :-)

This rig is still a work in progress, I do hope to get it on the air soon!