Thomas Martin, DF7TV, Stuttgart, Germany

Hello and Welcome!


My 'on the air' name is Tom and these pages are dedicated to amateur radio.

DF7TV 'On The Air'

Being a member of the Amateur Radio Club at the University of Stuttgart, I am QRV at the club station.

The biography of DF7TV at QRZ.COM shows an up-to-date description of the equipment used.


In February 2017 I began to make more contacts with other amateur stations from different countries/DXCC entities. My first aim was to get confirmed 100 different entities and become a member of the coveted DX Century Club (DXCC) of the American Radio Relay League, Inc. (ARRL). On May 15, 2017 my membership (CW #23,108) in the DX Century Club was attested by the ARRL. Since then I have been working to add additional entities. DF7TV DXCC CW award DF7TV-DXCC-ENTITIES-CONFIRMED

Working all Areas of a Country

Apart from working new DXCC entities, I like to work all areas of a country. DF7TV-Prefectures-of-Japan-Confirmed-Mode-CW DF7TV-States-of-the-USA-Confirmed-Mode-CW

Keymen's Club of Japan Award (KCJA)

DF7TV - some recent awards

Morse Code Training (25+ wpm)

Pacmandit by DF7TV

Morse Code Training shows a way of improving Morse Code proficiency at speeds above 25 wpm.

Morse Code Circuits

DF7TV: Symbol to label the side tone output socket

Morse Code Circuits presents some circuits related to Morse Code signals.



The regenerative Code Practice Oscillator sineCW30 provides a configurable, high-quality, Morse Code monitor tone.

Chuck, AA0HW, started the "sineCW" project in 2014 and is the main contributor. He provides several versions of "sineCW..." as a VSTi (Virtual Instrument) plugin. The plugin is made by first configuring several standard modules (oscillator, filter, controls etc.) in the program SynthEdit by Jeff McClintock and then exporting the circuit as a plugin. The plugin can be applied in a VST (Virtual Studio Technology) host. In 2024, I have refined one of Chuck's designs and called it sineCW30. It is a 32-bit (VST2) plugin. To create a tone at the output of the VST host's sound card, feed a keyed square wave signal (frequency about 4 kHz to 10 kHz, level about 2 V peak-to-peak) to its "Line-In" input.

Recording of sineCW30's audio output:

Links for additional information:

iCW Group at


sineCW30 plugin download folder

An RF Bias-Tee has been designed and built for a local club station. It includes a cascade of four inductors (L1 to L4), optimized to result in a high-impedance broadband choke (1 to 150 MHz).

Frank M Doerenberg, N4SPP provides in-depth information and extensive references on the Multi Band End-Fed Antenna. His publication helped a lot during the design and construction of a 160 meter band Sloping End-Fed Half-Wave (EFHW) Receiving Antenna at a local club station.

For a while, I have been experimenting with the K3NG Arduino CW Keyer. This keyer includes the option to set the keyer speed by a rotary encoder. In the original code, you may choose between "Full-Step" and "Half-Step" transition tables for the encoder. I have written additional code for a "Quarter-Step" state transition table. It is published as Quarter-Step_State_Transition_Table_for_Standard_Quadrature_2-Bit_Gray_Code_Rotary_Encoders.pdf. This code seems to support my rotary encoder (Grayhill 61C11-01-08-02) in a better way.

Wes Hayward, W7ZOI described (QST Magazine, June 2001) an RF power meter based on the AD8307 Logarithmic Amplifier and inspired me to build my PM8307.