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had 100000 visitors from 1998 to 2008.

Last update of this page: 14.07.2010

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This private homepage is mainly about amateur radio and homebrew electronics projects. The technical descriptions, white papers etc. focus on frequencies above 1GHz, as I find microwave electronics a lot more appealing than short wave stuff. But in the past I have done some QRP projects also that are published here.

And as on every good private homepage, you will also find information about myself, my other hobbies (running and photographing), my holidays and some fancy, non-amateur radio related projects. In the picture gallery you can find a selection of my private photo shots.

The latest and coolest projects 
(already available or to be published very soon)

A additional AVR Microprocessor within the WRT54GL wireless router

  • Adds a free programmable microprocessor to your Linksys WRT54GL wireless router (configured as WLAN client) 
  • Allows you to remote control your IT equipment and other devices at home over the internet
  • No need to let one of your PC's run all the time while you are away
  • Can be placed anywhere in your house or apartment  due to wireless connection to your home router

A frequency counter device for up to 12GHz signals

  • Lab bench device based on a fixed :1000 prescaler and the ATmega16 microprocessor counter 
  • Counts signals from below 500MHz to over 12GHz at input levels of -20dBm to +10dBm
  • With the new software, the counter also shows the signal drift in ppm/s (moving average over 16 cycles)
  • Description of prescaler given
  • Software available for download as source code and C and as binary for the ATmega16
Picture of 12GHz counter device
A universal RF measurement box for the lab bench

  • A RF power meter with over 50dB dynamic range (10MHz-3.5GHz or more depending on sensor)
  • High-precision frequency counter with external prescale-sensors (readings software-converted)
  • Scalar network analyzer functionality for sweeping filters, antennas, amplifiers, etc.
  • Fully automatic VCO evaluation (frequency  and output power vs. tuning voltage)
  • 16Bit digital to analog converters for controlling external analog circuits
  • DC volt meter up to 10 volts reading back outputs of external analog circuits
  • Fully controllable via RS232 PC interface
  • LCD display and analog meter for convenient stand-alone usage
  • Also contains a programmer for AVR microprocessors
  • Serves as cross-bar for connection of two more RS232 clients

A microprocessor based frequency counter for usage with and without prescalers

  • Software available for download in source and compiled for ATmega16
  • Schematic available for rebuilding the hardware
Pieces of ham radio equipment for the 3.4GHz (9cm) Band

Recently I started to build myself some equipment for 3.4GHz. Some of it is working very well so far, some other is about to be completed very soon.

  • A 3.4GHz beacon with 18.5dBm (70mW) of output power is already completed. Completely with PLL synthesizer on 1.7GHz, frequency doubler, filter and output amplifier. A little microprocessor programs the PLL and gives the call sign information in morse telegraphy every 20 seconds.
  • A homemade preselection filter (see picture) for image rejection is also completed. Apart for the SMA connectors and the PCB, it is purely made from material from the home improvement shop. With insertion loss of around 2.5dB and 30dB image rejection (for an IF of 144MHz) it even exceeded my expectations. Not to speak about the over 50dB suppression at 1.7GHz (=LO/2) and over 80dB suppression at 144MHz.
  • A very-low-noise amplifier using the low cost SiGe BJT BFP620 was designed for unconditional stability using the PUFF microwave simulator and was build to prove the concept. Click here to read the white paper on the convenient usage of modern bipolar transistors in ham radio LNAs and their many advantages over GaAs-FETs.
  • A first version of a receiving converter to 144MHz was build and tested. As always, I learned a lot while building the first prototype, so I decided to build another one without all the mistakes that I did in the first one. Anyhow, despite the fact that it does not have image rejection (i.e. noise figure is 3dB higher), it works quite well and I have heard the signal from my beacon all around the village already. 

RF & Waveform Generator

Generates RF-Frequencys 0.8-2.5 GHz (resolution 100Hz), 22MHz-512MHz (resolution 125kHz-1MHz depending on frequency) and Waveforms 0-100kHz (resolution 1Hz). Waveforms are Sine, Square, Triangle, Pulse, Sawtooth (positive and negative). All modes work independently and can be used at the same time. Very convenient user interface with LCD Display and up/down/cursor functionality. But please don't expect an easy to copy, 10 Minute instant design. The waveform part is a nice project for everyone, but the RF part is only for very experience hobbyists.
RF Power Meter 10MHz - 3.5GHz

Available now for rebuilding. Due to the many requests I received, I have developed a second, larger design that is easier to rebuild. There is a lot of theoretical and background information on the different sensor as well. Meters are Battery powered, handheld, about the size of a cigarette box (small design), with 3 different external sensors (thermal sensor, diode sensor, logarithmic amplifier), 2 integrated sensors (thermal and diode) in the big design, resolution 1/100 dB, absolute and relative power reading, two power ranges, battery voltage reading in 1/10 Volts. Additional features are now available for download with firmware version 1.4.
2.3GHz to 432MHz RX converter for Yaesu FT817

This very small RX converter fits on the backside (yes the small side at the back) of the Yaesu multiband allmode transceiver FT817. And it even operates on the internal batteries of the transceiver (without modification of the FT817). And it can be configured for either input frequencies around 2320 MHz or for the satellite downlink at 2.4GHz (very interesting for receiving satellite signals from the new phase 3D amateur radio satellite). Design is completed for quite some time, I just have to do the documentation. I will try to publish it asap.
My own electronic developments

For those of you that are interested in building your own equipment, here is some information about the things that I have developed. Please feel free to use every concept you like for your own developments. All provided software is distributed under the GNU public license, which means you can use if for private and commercial projects as long as put your derived code again under this license.

If you are interested in more information on one particular item, just send me a short mail. I would also appreciate your feedback/comments on everything you find here.

A word about software: For most of the projects that are published on this side the software (if the project includes a microprocessor) is available for download on the project page or I will mail it to you upon request. Usually I use Atmel AVR 8Bit RISC processors. The .ASM source code can be assembled with Atmels free IDE called AVR-Studio, which can be downloaded from their homepage. I will always try to offer both the .ASM as well as the assembled .HEX file for download. (If you assemble my .ASM files yourself you need to have the .inc file for the chosen processor in the same directory. All .inc files can be downloaded at Atmels homepage.) For AVR software that is written in C, I have used the free GNU C-Compiler which is available for download at the AVR-freaks homepage (including extensive manuals and installation guide). For experienced programmers I recommend the WinAVR-compilation with GCC 3.3. 
Complete Devices Stand alown devices like transceivers, receivers or complete measurement devices for your shack or your homebrew lab.
A high-quality narrow band FM Transceiver for 2.3 GHz (Right now the transceiver is only a receiver, I deceided to finish the transmitter somewhen in the future. The RX part is working very well and the documentation is pretty complete. (Schematics, concept descriptions, pictures, etc.)
A SSB/FM Receiver for 144 MHz (my graduation thesis) (This one is very detailed, including all schematic diagrams)
Handheld RF Power Meter for various Sensors 
(Available now for rebuilding. Due to the many requests I received, I have developed a second, larger design that is easier to rebuild. There is a lot of theoretical and background information on the different sensor as well.) 
A 1.5 Watts QRP-TRX for 7 MHz 

A facelift for the 7MHz-TRX (PLL, LCD-Display, digital tuning, etc.)

(Complete description including schematic diagram and a picture.) 

(This was only a little update project, I added a microprocessor, a PLL and a LCD display.)

Modules, parts of larger devices and little gimmick circuits. Single parts of larger projects that are not yet published. Also a few other circuits for the hobbist that are a bit to small to be called a project. 
A bootloader software module for the ATmega8 micro processor.  
(Available in assembly source code.)
A software module that enables the user of a micro processor circuit to update the software via a standard interface (RS232), without the need of using a programmer circuit or special interface. The source ode is extremely well documented so it can easily be used as a basis for individual bootloader routines.
A universal serial PC interface module.  
(Based on a AT90LS4433 8bit RISC Microprocessor)
The circuit consists basically of a AT90LS4433 AVR processor and a RS232 level shifter. Together with the software this forms a interface to your PC with digital inputs and outputs and 10bit-ADC inputs. Can be accessed via any terminal program or with your own homemade software. Nice to have for everyone that wants to control or measure something with a PC. 
A fuse bit blower for the RCEN bit in the AT90S1200 8bit RISC Microprocessor This circuit can enable a AT90S1200 to work without a crystal and therefore without any components around it! This is very helpful if the CPU is only used to program a PLL IC at the switch-on moment.
A cheap "software" DDS for producing the 10MHz reference clock signal for a 2.5GHz PLL 
(part of the RF-Generator mentioned above)
This circuit produces a very clean 10MHz signal that can be used as a reference clock for a PLL synthesizer. In this implementation the step width on 2.5GHz is only 25Hz!  (Mainly software running on a very cheap AVR RISC processor).
A low-cost high-performance RF power sensor for 1MHz to 6 GHz  
(part of the RF-Powermeter mentioned above)
A little circuit that converts RF power (-40..+16dBm, 1MHz..6GHz) into a DC voltage that can easily be measured with a multimeter. A conversion graph and table is provided. For professionals: A zero-bias Schottky detector with a resistive RF load for low SWR.
Frequency Converters Receiving frequency converters to receive signals on frequencies that your receivers don't cover.
A programable 2.3-2.4GHz to 144 MHz Receiver-Converter (new) (A simple but well working design, a complete description with schematics and pictures.)
A 2320 MHz to 144 MHz RX Converter (old) (Older design - not recommended, description with schematics for the LNA and the Mixer.)
A 50 MHz to 28 MHz RX Converter (Circuit description in English and in German, a picture of the circuit and the schematic diagram.)
Antennas and antenna matching Anything that has to do with antennas.
A double quad directional Antenna for 1296 MHz (Mechanical and electrical data and a picture.)
An active Receiving Antenna for 0.5 - 30 MHz (A close-up picture of the BF254 source follower.)
A simple HF antenna matcher in PI configuration (Just a picture, but should be enough to build one yourself.)
Other stuff Stuff that is not well documented or does not fit into any of the other sections.
A very simple, real "single-chip, zero components" solution for programming a LMX2320 PLL IC with a cheap AT90S1200  This may be very helpful for anyone that needs to program a PLL IC. For the moment only the software is published here, but there is not a lot more to it anyhow. How to connect the PLLs 3wirebus to the processor can be easily seen in the code.
A very stable freerunning beacon oscillator for 50 MHz (Just a picture to demonstrate that a circuit does not have to be pretty to work well.)
A Single Superhet SSB Receiver for 3.5 MHz (This was my first receiver development that really worked well. Pictures from the outside and the inside of the receiver.)

Non-ham stuff from here on... 


PC wakeup on call You want to access your PC at home when you are away? And you want to have it switched off to save power and to be sure that it is not hacked in the mean time? This is your solution. This little piece of electronics interfaces one of the analog phone outputs of your VoIP/DSL router to the power-on pin of your PC. Due to the use of a transformer and an optical coupler, everything is completely insulated and lightning protected. Give yourself a call from whereever you are and after 3 rings your PC will power on. What if your PC hangs up while you are away? Let it ring 7 times and you PC will hard switch off and is ready for a reboot.
Pathfinder Remember the little Mars-Explorer that NASA had sent to drive around on the Mars surface and make pictures? I was so impressed that I built my own little explorer. It is remote controlled on 430 MHz via DTMF and sends live Video-Pictures back on 2.3 GHz (FM-ATV). 
NiMH-Charger If you are using NiMH-Akkus for your GPS-Receiver, Digital Camera, etc. then you may be interested in this little super-low-cost solution how to charge them.
Mousetrap All of a sudden there was a mouse under my roof (and once also in my room). So I developed this mousetrap (to catch them alive, of course). Description with pictures (of the trap and the mouse).

My Trip throughout the USA in '98

Picture gallery in chronological order. Mostly nature photos and the story of a trip that ended quite unlucky for me.


My private photo gallery 

Here you can find a ever growing selection of my private photographs. Some of them are a couple of years old already, from the times when digital cameras where not as perfect as they are today. I am sorry for the poor resolution of these photos. 

The photos are grouped into categories with little thumbnails support those of you that are working on a dial-up line. 
Proceed to the gallery here. Feedback on the photos is always welcome.

If you have any questions or just would like to get in touch with me, I will be happy to receive your email at 

Unfortunately the spam-mail situation to my former email address became really bad. So I had to change the address and state the new one as bitmap. Sorry for the inconvenience.


According to German law (and my page is physically located in Germany) I would be responsible for the content on any web page I link to. The only way to liberate myself from that responsibility, is to distance myself from anything that is stated or shown on these pages. So I hereby declare that I have no clue what such a dumb law is good for, but I have no intention to get in conflict with German law-enforcement and therefore I do explicitly distance myself from anything on any other web-page, be it linked to by me or not. If you think Germany is the only country that has silly laws then be my guest and have fun at