08 July 2011

To Solf Or Not to Solf, that is the Question.

Last time I wrote about a new QRP - Transceiver - the Elecraft KX3 - I was fascinated about the concept mixing digital techniques with traditional craftsmanship in such a little box. I liked the boxes which were produced by Elecraft. So I was one of the first one in Germany, who build the famous K2 (1708), which is still going strong and my main rig.


I liked four things:

  1. I owned a top transceiver, which was comparable to commercial high class radios.
  2. In case I needed help there was the Elecraft reflector and the people from Elecraft, who solved all problems even on Sundays
  3. I build the TRX by myself. I soldered every resistor, capacitor, ... wound every toroid, transformer, ...put it all together.
  4. The documentation was more than excellent. Step by Step for Dummies like me. Testing was done in logical groups and when finished, there was a overall plan with all electrical values, ...

So when the K3 came out I thought, that it was time for something new. But I missed something. This rig with its digital components was more delicate to build. Trouble would have been on the way, so Elecraft decided to offer this rig as all assembled or as a no soldering kit. 

And when you read the description of the KX3 carefully, I think that this will also be a ready-build machine. Nice, with all features, optimized in every way BUT

THE FUN IS MISSING - no soldering required.

So I thought, when I really want to have a new or second rig I want to build it again by my own. And I remembered some time ago a blogpost: The SOLF QRP Transceiver. I looked into the QRP-Forum and there it was: The Solf is on its way to the QRP-Community.

SOLF Main Board © QRP-Project

Doesn't it look great? No SMDs. One main board and 28 modular sub boards. And it is a kit, which 
contains all the boards and components for the basic unit. The VCO band-pass filter and low pass filters for each band are modules and can be build and ordered at your convenienceSo it is possible to start with an inexpensive mono-band version and add the other bands later. 

Mainboard © QRP-Project

Here are some highlights:

Mainboard from behind with only 1 LPF © QRP-Project

VCO Module © QRP-Project
  • The basic kit consists of two quartz filters. (Total 4 crystal filters are available)
  • High-quality bandpass filters in the receiver input. We use T50 toroids, each band has its own preselector. 
  • Each band has its own VCO, whose bandwidth is only a little bit larger than the amateur band. Thus the phase jitter is kept as low as possible. 
  • A total of four crystal filters on the proven 9-MHz IF can be set to the optimal bandwidth in each mode. Each filter can be used in any mode of operation. 
9Mhz Filter © QRP-Project

  • Separate BFOs for LSB, USB and CW enable optimal adjustment.
  • Separate diode ring mixers for transmitters and receiver (2x TUF1). No compromises by double use of the mixers.
RX and TX Mixer © QRP-Project

  • Low noise IF with high dynamic and transparent control by using an improved cascade-IFs.  IF and SSB processing is done in their own shielded housings. No interference can take place from the outside.  
  • Switchable analog active filter can be added without delay and computer artifacts.
  • Full QSK without relays clicking and high CW tempos without any delay 
RX/TX Relais © QRP-Project

  • Buffered IF output, so that an SDR RX can be connected as a monitor (Pandapter without Problems)
  • Robust 10 watt amp with 12V RF MOS transistors
  • A text/graphics display and modern, ergonomic operation via touch-pad and buttons 
  • You can already look at the drafts of the manuals here.
  • And you can order it in the QRP-Project shop.
So I think "To Solf or not to Solf" is not the question if you want to have a top notch transceiver build by yourself. 

Imagine: Nearly 2000 parts. That is wonderful. You can sit every evening, when the sun is down and the cold is creeping through the windows, behind the oven and before the kitchen table with the kit. Heat up the iron and start soldering.

© QRP-Project

And when you have trouble with a sub group connect to the forum, post your problem and it will be answered while you sleep. So next day you can once again start and before the winter is finished you can proudly bring the SOLF to the air and call "CQ CQ CQ de DL1SDZ test first QSO with SOLF. "

© QRP-Project

Look at the ongoing story: How many secrets does a man need to SOLF?



Stay Tuned!