onsdag den 18. januar 2017

144 MHz EME - HW and cables

The complete system for 144 MHz EME.
The sketch above shows the complete EME system. The TRX (Yaesu FT-847) is placed in the radio room, and it is connected to the antennas as shown above. Control cables carrying 12V to relays, PTT, preamp, etc. are not depicted.

The receive path.

The sketch above shows the RX path. Number 1a and 1b are antenna feed points. Both of them are connected to the power splitter (2) where the antenna signals are combined. From the power splitter, the signal moves on to a coax relay (3) and from here it is routed to the preamp (4). After amplification in the preamp, the signal is sent via another coax relay (5) to the transceiver in the radio room (6).

The transmit path.

The sketch above shows the TX path. Number 1 is the transceiver inside the radio room. From here, RF (about 20 W) goes to a coax relay (2) and then to the SSPA (3). The SSPA amplifies the RF signal and provides 1 kW output. The RF power then goes to another coax relay (5) and continues into the power splitter (4) which divides the RF power between the two antennas. Each of the antenna feed-points is supplied 500 W (6a and 6b).

You can get more info on hardware, cables, and antennas by visiting this page: EME station and antenna for 144 MHz

Regards from OZ1BXM Lars
Homepage: oz1bxm.dk 

lørdag den 14. januar 2017

144 MHz EME - PC and peripherals

My PC and peripherals are connected as shown in the sketch below. This set-up is for my EME project.

PC and peripherals at OZ1BXM
1: Interface from ZLP Electronics.
2: Asus USB sound card.
3: Interface from ZLP Electronics.
4: Rotor controller ERC-3D from Easy-Rotor-Control
5: USB-to-serial adapter (FTDI chipset)
6: HP Compaq PC (Intel dual-core processor @ 3 GHz; 4 Gbyte RAM)
7: WLAN adapter
8: Transceiver Yaesu FT-847 with crystal heater QH40A installed.

Regards from OZ1BXM Lars
Homepage: oz1bxm.dk

mandag den 26. december 2016

144 MHz EME - Making 2 rotators play together

My EME-project is about to finish. One of the tasks is to make the azimuth and elevation rotors "play together" - that is tracking the Moon. My main software for JT65B EME will be WSJT by Joe Taylor, K1JT. WSJT takes care of the communication protocol, but it cannot control the rotators directly. You need different software for this.

PSTRotator is clever software made by YO3DMU. Its main purpose is controlling antenna rotators, but a Moon tracking facility is also available.

PSTRotator controls the antenna's azimuth and elevation.

Nr. 1. This window displays Moon data. 
Nr. 2. This is the PSTRotator main window.
Nr. 3 is an USB-to-RS232 converter.
Nr. 4 is the rotator controller ERC-3D. PSTRotator sends commands to this box.
Nr. 5a and 5b are manual control boxes. They supply power to the rotators.
Nr. 6a is the azimuth rotator (Yaesu G-600).
Nr. 6b is the elevation rotator (Kenpro KR-550).

PSTRotator is shareware - you can try it for free, but you must pay 20 EUR if used permanently.

Regards from OZ1BXM Lars Petersen
Homepage: oz1bxm.dk

mandag den 7. november 2016

ATF - a Danish ham radio rally

I visited a ham radio rally (the name is ATF) in Odense in November. The town of Odense is situated on the island of Fyn. This town is often used for meetings and conferences, because it is in the center of Denmark. People from Jylland (western part of the country) and Sjælland (eastern part of Denmark including Copenhagen) can drive there within a few hours.

This rally is held annually and it is quite popular among radio amateurs in Denmark. The stuff on display and for sale belongs to the category "general ham radio". Other rallies are more focusing on special branches of our hobby, for example VHF/UHF/Microwave.

There are several attractions when attending a ham radio rally:
  • You can purchase equipment, both home-made and factory-made
  • You can buy all the spare parts and cables you need
  • You can listen to lectures on different subjects
  • You can meet old friends and make new ones
  • You can visit boots manned by specialists (e.g. "50 MHz")

ATF in Odense 2016-11-06.
The picture above shows the crowd in the morning. Everyone is busy checking the offerings on the tables!

Vy 73 from OZ1BXM Lars Petersen
Homepage: http://oz1bxm.dk

tirsdag den 1. november 2016

WSPR on 30 meters - my findings

I let WSPR run on 30 meters during 13 days of October 2016. The purpose was to learn how my antenna performed on 10 MHz.

My antenna is a loop skywire: 43 meters of wire shaped as a rectangle. The antenna configuration is shown below:

My loop skywire antenna.
The WSPR results were not as expected. I hoped to hear more continents. The average number of continents heard per day was 2.2. Not impresssive. I would have expected hearing at least 3 continents each day. 
Continents heard with WSPR on 30 meters (October 2016).
When I compare the results for 30 meters with those of the 40 m band, it is clear that this antenna performs better on 40 meters. 

OZ1BXM Lars Petersen
Homepage: oz1bxm.dk

onsdag den 5. oktober 2016

WSPR on 30 meters

I had my first experience with WSPR in 2009 and I wrote a piece about WSPR on my blog. Three months later, I published another piece: Reaching worldwide with WSPR. Then I moved on to JT65 in order to make real QSO's on the HF-bands. As you know, a WSPR contact does not count as a QSO.

I have been little active on 30 meters (less than 100 contacts), so I've decided to run WSPR on this band. The purpose is to learn how my antenna (loop skywire, 42 m of wire shaped as a rectangle) performs on 10 MHz.

My experiment begins on October 8th, 2016 and is planned to run until the end of the month.

OZ1BXM Lars Petersen
My homepage: oz1bxm.dk

lørdag den 27. august 2016

Code Practice Oscillator

The Code Practice Oscillator pictured below was developed by me. It is simple and easy to build. It is based on the 555 oscillator IC and is powered from a standard 9V battery. The loudspeaker is mounted on a separate PCB and the two boards are connected with metal spacers. The whole assembly requires no cabinet - and that reduces building time!

Homemade Code Practice Oscillator
Training morse code reception is pretty much covered already by the aid of hardware-based morse trainers, PC programs, app's for smart phones and tablets, etc.

Sending morse code is another case. The obvious solution is to use a keyboard and let the software do the job. This solution works, but you will be missing the touch and feel of dots, dashes, and spacing provided by a manual key. I would recommend a novice sending morse code using a real morse key, and move on to more advanced devices and higher speeds at a later time. 
Circuit Diagram
Another benefit of building your own Code Practice Oscillator is the proudness gained from a successful project. Building skills like reading a diagram, soldering components, connecting wires, and mounting a loudspeaker are all learned during this project.

Best regards: OZ1BXM Lars Petersen
Homepage: http://oz1bxm.dk