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RTL-SDR bandpass-filter and DIY coax-notch filters

Details
John, DK9JC & AK9JC
Equipment
01 November 2016
Tuning the front-end filters

Some days ago I decided to install an APRS RX-only iGate here in my apartment. The iGate simply takes the APRS signals from the air and forward them to the internet. I live almost in the center of the city and I have a free sight over the buildings. Good preconditions for a „fill-in“ iGate I thought. I had a Raspberry Pi and a cheap RTL-SDR dongle (DVB-T stick) for this purpose. Sounded like an easy job first but I received nothing within the next 12 hours. I knew that something must be wrong. In this project I learned more on designing HF-filter than on Linux and Raspbian, what actually was my aim at the beginning of this project. In this blog post I will show you, how I successfully dealt with massive QRM from two 100kw and 2 50kw radio transmitters.

Read more: RTL-SDR bandpass-filter and DIY coax-notch filters

FT-817 CAT-interface with built-in USB soundcard

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John, DK9JC & AK9JC
Equipment
24 October 2016
FT-817 interface for digimodes

Some time ago I bought one of these small and light 2 in 1 tablets with Windows 10. The device was very small in size but the battery lasts very long. With only 1,7kg the weight was not too high for my portable ops. I did not take it into the field yet. The reason was simple: The tablet has one USB-port only. I need one port for the USB cat lead and another one for the USB-soundcard to connect my existing PC-interface made by Alan, M0AQC. After a long search on the internet I did not find a simple FT-817 interface with one USB lead, CAT-control and built-in soundcard. So what did I do? I built an interface that meets my requirements by myself.

Read more: FT-817 CAT-interface with built-in USB soundcard

SOTA: DM/RP-400 Großer Adelberg - 15.10.2016 - DX mit ZL1BYZ und ZL1TZW

Details
John, DK9JC & AK9JC
SOTA
18 October 2016
SOTA: DM/RP-400 Großer Adelberg

Auf dem Weg zur Rheintal Electronica habe ich noch den "Großer Adelberg" (DM/RP-400) bei Annweiler am Trifels aktiviert. Dieser lag direkt auf dem Weg, ich musste einfach nur von der Bundesstraße abfahren. Da zwischen 06:30h und 08:30h UTC das Band Richtung Australien und Neuseeland öffnet, bin ich entsprechend früh los gefahren. Auch wenn die Chance auf ein QSO mit VK oder sogar mit ZL nur sehr gering war, habe ich den Rucksack entsprechend gepackt. Neben dem FT-817 habe ich auch meine kleine Endstufe (MX-P50M) und entsprechend "dicke" Akkus eingepackt. Als Antenne setzte ich meinen "Schrottkisten-Dipol" aus altem Lautsprecherkabel ein.

Read more: SOTA: DM/RP-400 Großer Adelberg - 15.10.2016 - DX mit ZL1BYZ und ZL1TZW

FT-817 smartphone interface for PSKdroid and APRSdroid

Details
John, DK9JC & AK9JC
Equipment
14 October 2016
Built FT-817 android interface

Some time ago I came across the Wolphilink Interface. It's a small box which connects an smartphone to a Yaesu FT-817/857/897 transceiver. I was about to buy one, but the interface was quite expensive, especially if you include the optional cables and the shipping to my QTH in Germany. I googled a bit and found an interface built by Christian Petersen, DD7LP. I made the decision to take a closer look on his schematic diagram and built my own interface to use APRSdroid and PSKdroid on my FT-817. Luckily Christian also provided a buying list besides the schematic diagram. As I don't have any knowledge and also no tools to etch a circuit board, I first planned to build the circuit on a simple stripboard.

Read more: FT-817 smartphone interface for PSKdroid and APRSdroid

Li-Ion battery pack (18650s) for the FT-817 and KX2 and comparision on RC Li-Po and LiFePo4 packs

Details
John, DK9JC & AK9JC
Equipment
09 October 2016
Built 3S1P 18650 pack

In this article I will describe how I built a cheap DIY 18650 Lithium-Ion battery pack for my Yaesu FT-817. After 65 SOTA-activations and other outdoor operations like IOTA, WWFF I had to reduce some addional weight of my „go-bag“. I already went from RG-58 coax to RG-174 and also scaled-down the diameter of the antenna wire, but this is a different story. So I looked what is on the regular market and found a lot of people in the amateur radio scene who are using Li-Po (lithium polymer) packs. Those packs are usually made for RC purposes and in the first moment I thought that they perfectly matches all of my needs. They are cheap ($15 per 2500mAh pack) and a 3S pack (3 cells in series) gives 11.1V nominal output.

Read more: Li-Ion battery pack (18650s) for the FT-817 and KX2 and comparision on RC Li-Po and LiFePo4 packs

US Extra-Class bestanden

Details
John, DK9JC & AK9JC
US Amateurfunk Lizenz
24 September 2016
ARRL Lizenzprüfung

Nachdem ich dieses Jahr auf der Ham Radio die Prüfungen für die US-Amerikanische Technician- und General-Class absolviert habe, wollte ich natürlich zeitnah auf die Extra-Class, welche die höchste US-Amerikanische Klasse darstellt, upgraden. Problematisch ist dabei die "Karenzzeit" von genau 365 Tagen, danach verfallen vorher bestandene Elemente. Ich müsste also nach einem Jahr von vorne beginnen. So kam es mir dann sehr gelegen, dass Eugen, DK8VR - unser Distriktsvorsitzender hier im Saarland - mir davon erzählte, dass Planungen laufen, um bei unserem Distrikt-Service-Tag eine US-Lizenzprüfung anzubieten. Mit Mike, KK7CW war der erste Prüfer (VE) schnell gefunden, Jean-Luc, AC8QS war der zweite und Arnaud, AC2NK kam extra aus der Nähe von Straßburg angereist, nur um die US-Lizenzprüfung abzunehmen.

Read more: US Extra-Class bestanden

More Articles …

  1. SOTAbeams Mountain EFHW Tuner 40-17m kit
  2. SOTA: DM/RP-311 Rossberg - 31.08.2016
  3. Ultralight QRP endfed antenna (0,14mm²/26AWG)
  4. SOTA: DM/RP-272 Donnersberg - 27.08.2016
  5. SOTA: DM/HE-097 Steinkopf - 27.08.2016
  6. SOTA: DM/RP-187 Wildenburger Kopf - 21.08.2016
  7. MX-P50M 50W HF PA for FT-817 and KX-3: How to use the amplifier on datamodes
  8. Leichter Portabel-Dipol aus der Schrottkiste
  9. SOTA: ON/ON-016 Les Aisances - 12.08.2016
  10. Versuchte Aktivierung von IOTA EU-146 Zeeland
  11. SOTA: ON/ON-004 Bois de Hazeille - 08.08.2016
  12. SOTA: DM/BW-385 Mauzenberg - 27.07.2016
  13. SOTA: LX/LX-004 Widderbierg - 17.07.2016
  14. 06. - 07. August: Internationale Deutsche Meisterschaft 2016 im Amateurfunkpeilen (ARDF)
  15. SOTA: F/VO-055 Le Mottenberg - 03.07.2016

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  • Li-Ion battery pack (18650s) for the FT-817 and KX2 and comparision on RC Li-Po and LiFePo4 packs
  • US Extra-Class bestanden
  • Amateurfunk Klasse E (CEPT-Novice) – Erfahrungen nach knapp einem Jahr
  • Mag Loop Magnetic Loop DIY with trashed 26 inch bicycle rim
  • APRS Kabel für Baofeng und APRSdroid selbst gebaut
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