Thomas Martin, DF7TV, Stuttgart, Germany.

Hello and Welcome!

I am a radio amateur (callsign: DF7TV)
and these pages are dedicated to ham radio (or amateur radio).
ma carte QSL

My "QSL" card used to confirm contacts to other radioamateurs.

(External links are shown here as "[N° of the link]" and the according links are listed at the bottom of the page.)

Address and a picture of the operator are available at WWW.QRZ.COM
(Enter "DF7TV" into the "Callsign" field at the upper left corner at QRZ.COM)

Elecraft K2

Building Elecraft[1] K2 transceiver kits is fun and so I built serial numbers 2383, 2759, 3105 and 4138. Some information about the latest K2 built (S/N 4138) is available.

Sverre Holm, LA3ZA provides an excellent unofficial guide to Elecraft K2 modifications[2]. His tables with comments and links will be of great help, especially if you are not a permanent "listener" to the Elecraft e-mail list at QTH.NET to keep track of all those ideas.

A collection of links to K2 semiconductor data sheets may be useful when it comes to modifications or if you are trying to get a deeper insight into the K2 circuit details. (Links to data sheets of nearly all semiconductors used in any Elecraft kit -- not only in the K2 -- are provided.)

Elecraft KX1

The KX1 is the Ultra-Portable CW Transceiver Kit kit from Elecraft[1]. Some information about theKX1 I built (S/N 906) is available.


Dan Tayloe, N7VE has been so kind to send me a revised presentation of his NC2030 CW-transceiver[8] using the Tayloe detector and you may download the according files (look for reference "[8]" further down this this page).

On September 2, 2005 Norcal was pleased to announce the availability of the Norcal NC2030 kit. Please use the up-to-date info about the NC2030 and the NC2030 kit on the NORCAL page[11].

The NJQRP -- New Jersey QRP Club[4] / AmQRP -- American QRP Club[5] has a lot of interesting items like the DDS-daughtercards for the AD9850 or for the AD9851 and the AA-908 Antenna Analyst sold as kits.

The Antenna Analyst AA-908 kit of the AmQRP[5] has been completed May, 2005 and successfully applied during portable operations.

The building and testing of a Power Meter using the AD8307 has been very satisfying -- really astonishing what an accurate instrument one may get with so little effort. I simply called it PM8307 and think its voltage output (..well sometime in the future) will be fed to a scope or A/D converter for further applications.

At this time I am experimenting with a SoftRock RXTXv6.2 kit. This is my first software defined radio transceiver and it is developed by Tony Parks, KB9YIG et al.. I bought the kit for 40m/30m which I'll use only on the 40m band. There is a group at yahoogroups called "softrock40" and a site "" where you may find further informations on this interesting transceivers which allow for a really good introduction to software defined radio.

Some experiments[15] were made using the SI570 XO/DCO (digitally controllable crystal oscillator from Silicon Laboratories) which probably will replace the crystals in my SoftRock RXTXv6.2 transceiver. The main components are the SI570 DCO on a board made by WB6DHW, a PICAXE microprocessor 28X1, a Microchip EEPROM 24LC256 (32kByte) and a (serially controlled) LCD. Band/frequency changes at this time are accomplished by two simple potentiometers connected to two of the A/D converters of the processor. Further SoftRock RXTX experiments ( SR1004 )are made which will add the SI570 oscillator and a PennyWhistle RF power amplifier to the assembled RXTX kits to get a multi-band transceiver[16].

DF7TV On The Air

Being a member of AKAFUNK[6] -- the ham radio group of our local university -- I am qrv in CW using our callsign DK0SU. I am also qrv from home using my indoor antenna but I admit that using DK0SU's antennas is a lot more fun.

EQP -- Elecraft QSO PARTY

The rig of DK0SU has been used for the Elecraft QSO Party (EQP) in 2004. Thank you for all the nice contacts! The score here is 72 for 36 QSOs using 15 Watt output power during EQP 2004. For those interested in details the log for EQP-2004 at DK0SU is available as an ASCII-file; results of the party and some comments are available at the Elecraft[1] homepage (search for "EQP Results" within the SEARCH field at the lower left of their main page).

DK0SU took part in EQP 2005 (March 12 to 13, 2005) again. And again thanks for the nice contacts!. The score here is 192 for 64 QSOs using 5 Watt output power during EQP 2005. For those interested in details the log for EQP-2005 at DK0SU is available as an ASCII-file.

DK0SU took part in EQP 2006 (March 11 to 12, 2006)Thanks for the nice contacts!. For those interested in details the log for EQP-2006 at DK0SU is available as an ASCII-file.

DK0SU took part in EQP 2007 (March 10 to 11, 2007) In 2007 I made only a few but nice contacts -- A BIG THANK YOU! For those interested in details the log for EQP-2007 at DK0SU is available as an ASCII-file.

CT3/DF7TV, QTH: Madeira (Portugal)

DF7TV was QRV from the island of Madeira as CT3/DF7TV from December 21 to December 29, 2004. Rig has been a KX1, a PAC-12 or wire antenna and about 2Watts output. Biggest success has been to work GM3OXX,George from Clunie, Scottland who had only 1 Watt of output power. For this QSO on the 20m band I used the KX1 at 2 Watts and a wire antenna of about 17m length at about 6m height above the Cabo Girao (Europe's highest cliff, about 600m above sealevel) in southern Madeira. With the same assembly I worked VY2DM, Doug from Charlottetown, Prince Edward Island (Canada) -- he gave me a 579 -- not bad I think. A strong wind blew on the cliff but the results were worth catching a cold. Some pictures I made make me feel the "Fado" -- how easy life is, when the only decision to be made ist wether to do some portable ham radio or do a "Levada" (famous water channels on Madeira) walk or a combination of both.

F/DF7TV, QTH: Paris (France)

DF7TV was QRV from Paris and the outskirts of Paris from August 20, 2005 to September 3, 2005. Staying at l'Hôtel République, 31, Rue Albert Thomas, 75010 Paris (10. Arr.) I was lucky to visit F5KTR[10] the clubstation of radioamateurs working for the french railroad (SNCF) nearby the Gare de l'Est in Paris. The Elecraft KX1, K2 a PAC-12 whip antenna and some wire antenna have been presented during a meeting of the club members to which I have been invited. It is really nice to feel the world-wide community of hams, especially when you are alone in a new city. My portable activity took place at a small hill nearby the Palace of Versailles -- a wonderful region to do hamradio. If you like like CW and like to improve your French (like I should...) it's perhaps a good idea to join the Union Française des Télégraphistes l'UFT[12] -- J'ai déjà mon "numéro UFT" -- N° 1170 (Merci à mes parrains F6ICG, F8BNV, F2YT, F6IRY et F6ENO).

UFT HF Contest

DF7TV was active during the UFT[12] HF Contest on December 10/11, 2005 using a K2 transceiver in the QRP category. The antennas at DK0SU helped a lot during the contest. Made 76 QSOs and 28386 points here. For those interested in details the log for Concours UFT HF-2005 at DF7TV is available as an ASCII-file. Merci pour les QSO sympas, 73 et à bientôt!

DF7TV was active during the UFT[12] HF Contest on December 9/10, 2006 using a K2/100 transceiver and a Heathkit SB-220 amlifier. The antennas at DK0SU helped again in the contest. Made 104 QSOs and 109200 points here. For those interested in details the log for Concours UFT HF-2006 at DF7TV is available as an ASCII-file. Merci pour les QSO sympas, 73 et à bientôt!

F/DF7TV, QTH: Six-Fours-les-Plages/Toulon (France)

DF7TV was QRV from the region of Toulon in South-East France from April 27 to May 9, 2006. Bands used were 40 (preferred 7013 kHz), 20 (preferred 14060 kHz) and 30m (preferred 10115 kHz), CW only, rig was an Elecraft KX1 at abt 2 to 3 Watts, antenna was a PAC-12 vertical with a prolonged radiator. Preferred portable QTH has been the small hill Mont Faron near Toulon. Accessible by an aerial ropeway this has been a real nice place and I had a lot of QSOs from there at a height of about 500m above sea level. Thanks for all who listened to my QRP signal and to F5PVX, (Merci! Michel) who recommended this beautiful QTH.
Et un grand MERCI! à Norbert, F6AXX et à Maurice, F5NQL de l'UFT[12] qui m'ont accueilli quand j'arrivais en gare de Toulon.

GACW WWSA DX Contest (CW) 2006 and 2007

DF7TV was active during the WWSA DX (World Wide South America) CW Contest on June 10/11, 2006 using a K2 transceiver and the (just-in-time assembled) KPA/KAT100 in the LOW category (100 Watts). The antennas were the V80S vertical and X7 beam at DK0SU. Made 309 QSOs and worked more South American stations (especially from Argentina) than in my whole ham career before this contest. My newest toys from Elecraft; the amplifier KPA100 and the automatic matching network KAT100 worked reliable during the 24-hours contest. This contest is organized by the GACW[14] Grupo Argentino de CW. Gracias/Obrigado/Thank You! for all the nice contacts and I hope to meet you again soon. For those interested in details the log for contest WWSA CW-2006 at DF7TV is available ( ...being proud of my second place in the category "LP-DX = Low Power (100w), DX"; congrats to NP4N, Enrique Vera - the winner in this category!

DF7TV was active again in this contest in 2007 -- this time QRP using the K2 at 5 Watts only. Gracias/Obrigado/Thanks for all the nice contacts!
For those interested in details the log for contest WWSA CW-2007 at DF7TV is available.

Swiss HTC-QRP-Sprint-Contest (CW)

DF7TV was active during the Swiss HTC-QRP-Sprint-Contest of the „HTC“ Helvetia Telegraphy Club[13], Switzerland on September 9, 2006 using K2 transceiver #4138 at 5 Watts output power and the antennas of DK0SU[6]. Antennas were the V80S vertical and dipoles for the 80/40m bands and X7 beam for the 20m band. Made about 40 QSOs and the most interesting part was picking weak stations out of the noise on 80m during the last two hours of the contest. Thanks for the nice QSOs especially for those with VLP stations using less than 1 Watt of output power! The results of the contest are available at the internet site of the HTC[13].

EUCW 160m Contest (CW)

DF7TV was active during the EUCW 160m Contest (CW) organized by the UFT[12] on January 6/7, 2007 using a K2/100 transceiver. The antennas were a Titanex V80S vertical for transmission and a double dipole for 80/40m for reception on 160m because the noise level delivered to the receiver using the vertical V80S was very high. For those interested in details the log for contest EUCW 160m - 2007 at DF7TV is available. During this contest I made only about 80 QSOs but thanks to the antennas at DK0SU these are more QSOs than I made in my whole radio amateur career on 160m before this contest. Thanks for all the nice QSOs.

Using the following links you will leave WWW.QSL.NET/DF7TV.

[1] Elecraft, Aptos, CA

[2] Unofficial Guide to Elecraft K2 Modifications by LA3ZA

[3] FlexRadio Systems, Austin, TX

[4] NJQRP Club, NJ

[5] AmQRP Club

[6] Clubstation DK0SU, Stuttgart, Germany

[7] Pacificantenna

[8] Presentation of the NC2030 CW-transceiver of Dan Tayloe, N7VE

[9] Des pages en français de DF7TV

[10] Groupe des Radio Amateurs Cheminots - radio club F5KTR, Paris, France

[11] Norcal NC2030 Transceiver Kit (Dan Tayloe, N7VE)

[12] l'Union Française des Télégraphistes -- l'UFT

[13] Helvetia Telegraphy Club, Switzerland

[14] Grupo Argentino de CW

[15] DF7TV's notes on SI570/PICAXE experiments

[16] DF7TV's notes on SoftRock RXTX experiments

Thanks for your time,
73; I hope to meet you on the bands.
Thomas, DF7TV, April 13, 2018.