Elecraft K1 4 band QRP Transceiver
A little QRP masterpiece built in Feb 2007
Updated 7.5.07   

What it is

This is small but sophisticated, multi-band, 5W, QRP CW rig combining a simple single conversion superhet receiver, a mixer-VFO controlled transmitter and a powerful control and display system, all in a small and very attractive box. 

There are almost no wire connections to be made. The circuits are built on 4 small double sided silk-screened PCBs that plug together. Be warned: there are plenty of toroids to wind!

Added features include a memory keyer that can be used to send 2 programmable pre-saved CW messages.

There are a number of self diagnostics built in to the transceiver allowing monitoring of supply voltages and other "vital organs". When built, this is a classy product.

The Elecraft website picture showing the size of the K1 alongside a 9V battery. It is about the same width as an FT817.

Spec

• RF power  adjustable from 0.1 to >5W (max 7W in my case on the lower bands)
  
• RX sensitivity 0.25uV for 10dB S/N. MDS in my case was better than -130dBm.
• Clean, quiet, non-synthesised design. With the narrower front-end filters in the 4 band design it works fine in Europe on 40m at night without any attenuation.
  
• Selectivity adjustable from 800Hz down to 250Hz via processor controlled varicap diodes adjusting the ladder crystal filter.
  
• 80-15m bands (up to 4 at a time) although designs exist for 160, 12 and 10m bands.
• Optional internal auto-ATU, noise blanker and internal battery pack.
• 3 digit LCD display.

Building it

INVENTORY
The first stage was a parts inventory, which is essential as the kit contains a lot of parts both electrical and mechanical. Care needs to be taken not to lose screws, washers and other small parts: in all there must be in excess of 1000 parts in the kit.

INSTRUCTION MANUAL
Elecraft make radio kits in a way that everyone else should emulate: the instruction manuals are clear, filled with detail and almost leave nothing to chance.  If you are old enough to remember Heathkits you will have an idea of the format: step by step instructions with a tick box to remind you that you've completed the step, "on the way through" checks of DC resistances, currents and voltages, and clear diagrams and circuits.

FOLLOW THE INSTRUCTIONS!
Having said this, it is still necessary to read and follow the instructions carefully. If like me you don't, then you will have to correct your mistakes: I fitted some of the resistor networks incorrectly and also nearly fitted a coil back to front. My recommendation is to take things slowly and carefully.

TESTING  ....AND A PROBLEM FOUND
When mine was completed the receiver was very deaf: I guessed around 30-40dB by ear. Luckily I was able to verify this on a borrowed signal generator so I knew I had a problem. Elecraft recommend a signal tracing technique in the manual which I followed. This immediately led me to the audio mute circuit where the signal levels were below those suggested in the manual.

FIXED!
Sure enough, the culprit was the 2N7000 which is used to mute the RX signal when on TX. Removing this part restored the receiver to full sensitivity. I had a spare available so was able to fit this. This fault was probably caused by static damage; although I had been extremely careful this part was loose in the pack and not static protected as the other devices in the kit were. I think this was a packing error or it had become loose in transit.

Operating On-Air

EARLY SUCCESS
Having built the kit, and set it up as explained very carefully in the manual, it was time to try it out on the air. Work was completed a couple of days before the ARRL DX contest in Feb 2007 giving a great opportunity to test it on-air.

There is only one thing to say about this little unit: it is brilliant.  In a few hours of operating contacts with the USA were made on 40, 20 and 15m - there was no contest on 30m - using just a 15m wire down the garden strung from the guttering (6m high) down to a post at the far end about 3m high.

DXCC?
I have the feeling this little radio is going to get quite a lot of use in the next few years. DXCC is entirely possible with the K1-4 and a small wire antenna and I'm relishing the challenge as the sunspot numbers start to climb.

                  Picture shows my K1 along side the MFJ Cub, Micro 80, FT817 and IC703

Links

Elecraft main website
SSB modification
10m/12m RF board mod
eHam.net K1 reviews

www.elecraft.com
www.it.geocities.com/giulianoi0cg/ www.jl3amk.org/en/index.htm#k1_mods_12m_10m www.eham.net/reviews/detail/846  

Other comments

If buying from the USA and you live in Europe don't forget that you may have to pay VAT and in the UK this adds 17.5% to the final shipped costs. This makes this more expensive, but in my view still worth it in my opinion.

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