04 January 2012

To SOLF or Not to SOLF ... (English Version)

(This article was published in the German magazine CQ_DL (1/2012). It is a rough translation. A shorter version was published some months ago)



... That is the question.



The life of a radio amateur is not easy. Important decisions must be made ​​and the critical eye of his wife wanders over the radio shack and is surprised by the asexual reproduction of the tiny boxes. Unfortunate!


The state of affairs

For over 20 years I am a ham, had problems with my hidden antennas, do not like contests, owner of about 5 QRP transceivers from a total population of about 20, like to listen a lot, avoid clusters and hide microphones for I am a CW fetishist. Actually, I'm just a normal radio amateur?


But there was still something

In former times everything was better! You sat in the warm room, turned on the receiver button, the magic eye shone, and the OM on the other side wanted to chat. Later you went to the local ham radio club, had technical discussions and a fine beer and the QSL cards came as a greeting from a distant world ; ...

And now everything is even better! You look at the ham weather; control the cluster, press the mouse on the exotic call, confirm with F1 his call, send with F2 the report and receive a few seconds later the eQSL; ...

And then I stumbled on the QRP forum in Germany over a discussion that has developed since 2007. The topic: a new transceiver concept.


The SOLF = A new QRP transceiver

It sounded tempting:

It is an amateur radio TRX with 9-bands and bandpass filters with high-quality receiver input. Each band (160m - 10m) has its own VCO. Disadvantage: You can not listen to normal radio,stations because the range covers only the amateur bands. Advantage: The selection is very good.

I am a filter freak. I do not want to hear five signals, but only one thing. There are four crystal filters available on the proven 9-MHz IF for SSB and CW. But you must not follow the developers. You may develop your own filtering concept (eg CW only)! Good thing.

Each mode LSB, USB and CW has its own BFO. There are separate diode ring mixer for transmitter and receiver. The IF should be very low noise and have a high dynamic range. Switchable analog active filter without time delay and computer artifacts and a free full QSK relay antenna switching. Since I do not know how to connect a microphone ;-) and the relay clatter of my FT-817 CW is stretching my nerves, this is an appetizer: CW high tempos without any delay and without noise. 10 watt amp good: QRP is not everything.

Buffered IF output, so that an SDR RX can be connected as a monitor. Since I've joined the PMSDR with my K2, I finally see, in split mode, the CW-hunter and the hunted person.



This seems to be a very good, full QRP transceiver. But advertising is and remains advertising and a man is a born skeptic. Four years of development, four experienced lead developers, 29 boards, 2000 components, about 900 € and you still have to buy the soldering iron.



The design of the SOLF

I'm not an engineer and had to cram more than a year to pass the amateur radio examination. And I have since forgotten (almost) everything. My interest: Communicating with people with the lowest performance, but with the best equipment I can afford.

So I can not answer the question about the technical quality of the kit. I must find other criteria: trust. Trust in products that were developed by many dedicated people together. I trust the QRP-Project, the developer or group of the SOLF, that they have achieved in the long years of development, the best result.

And where does this trust come from? Many years ago I wrote an article about Linux as the basis for a radio-based Web. Linux is developed to this day by thousands of programmers who have a common goal: to develop the best operating system. It worked. Linux is now the basis for Apple's OS and Android. Today, these collaborations are called "crowdsourcing" and the results are amazing.




This same commitment to a goal coined Peter Zenker (DL2FI) and his group of developers in recent years. They worked together for a very long time. The discussions were (mostly) public. Anyone who wanted was invited to participate. The plans and documentation are (almost) "Open Source". They are distributed in the forums and discussed openly. Nothing is hidden. It is lived amateur radio, which really has always been "open source". This makes for me from the core of amateur radio idea. I must therefore do not understand the whole concept of SOLF, because I trust that these amateur radio operators have given their best to achieve the design goal.


Soldering and construction

Why should I build a transceiver by myself? If I buy one, I can have the additional 70 menus and 40 buttons. Because it's fun to create something for myself with my own hands.

But does the kit really need nearly 2000 parts? The development group uses the modular technology to facilitate the construction. The 2000 parts are distributed over 29 boards. Each board is devoted to a function and can be tested in isolation. One has not, like in guitar construction, to finish the whole instrument to hear the first tone. The manual has the hidden title: "SOLF for Dummies".Step by step illustrations accompany you.

And if I run into problems? Now another group comes into the game: The group of self-builders. They organized themselves in forums and chats and accompany themself in the construction of SOLF. No tears, no question remains unanswered. I've had this experience years ago during the construction of my K2. Again, there was an appropriate discussion forum. If you had a question: You typed it cheerfully into the PC. The question mark had not disappeared from the screen, when the email client announced an answer - evening, night and Sunday, open 24 / 7 - Guaranteed.




You have to see it positive: Imagine 2000 parts, the sun has gone The cold creeps through the window, you sit behind the stove in front of the kitchen table, the soldering iron is smoking, the computer hums and here comes the first question: "How to solder the elko #247". Your blook at your already soldered board and write: "Plus is in the direction of resistor #287. 72 de dl1sdz.

The prize

This is a really critical point. When I began to build radios, money always played an important role. I wanted to have transceivers that I could not afford. Today this has changed. You can buy a commercial transceiver with all the features 600 - 800 Euro. You get a warranty and (perhaps) service. And if the box does not work, you can send it back again.

So why should a normal person incur the trouble of having to buy a 2000-piece puzzle and find the solution to solve the mystery?
  • Because it is a challenge.
  • Because it's fun to tinker .
  • Because you have to understand the device in order to build it
  • Because you have at the end your dream transceiver
  • AND because you can finally once again actively engage with the community of amateur radio operators

The SOLF and the Future

But the story of my self-persuasion was not finished yet. The SOLF is an open system and is actually called CREATIVE SOLF. One can and should continue to develop it. If you have a better solution for the filter or the audio amplifier: No problem! Each board has a defined interface with inputs and outputs. These values ​​must be respected. But on the board you can realize your own solutions. I am not able to offer my own technical solutions. But I know that there are discussions about alternative solutions. And if I'm interested in this technical solution, I gcan go for this goal - with a little help from my friends


I would like to

participate, it is not an easy kit. But I know that with the help of other hams I am able to build the SOLF. And one day I will have another self-made piece of jewelry on my desk. And on the next day you will hear somewhere in the ether: "CQ CQ CQ de DL1SDZ Test first QSO with SOLF." We will see who responds to my call. Perhaps it is Shakespeare who replies, "That was not the question! Please read my Hamlet again more carefully".



I already started a small construction diary in my blog "How to Solve the Magic SOLF Puzzle". You can find it in the table of contents.