tirsdag den 16. maj 2017

My Elevation Rotor is "frozen"

Some weeks ago, my elevation rotor KR-550 "froze". It does not move, and the elevation is fixed at 45 degrees.

The elevation rotor is more than 10 years old, and this kind of problem seems to be "normal" with this rotor. A search on the net showed that other hams have had the same problem, e.g. PA1IVO. I am now going to repair it following his advice.

My first EME QSO is unlikely to happen until the rotor is fixed.

Vy 73 from OZ1BXM Lars Petersen
Homepage: oz1bxm.dk

fredag den 7. april 2017

144 MHz EME: CQ heard

Last evening, just before midnight, the Moon was high in the sky, and the Sun had set more than 1 hour ago. The degradation was about 2.0 which means good conditions. I watched out for EME-signals, and I used the EME-chat (N0UK) as a guideline for their frequency. The EME-chat is mandatory because you want to know where the different stations are calling. Below is a cropped screen-dump of the WSJT-X Wide Graph waterfall (times are in UTC):
OK1DIG calling CQ on 2m EME.
OK1DIG decoded by WSJT-X (JT65B). 
WSJT-X decoded the JT65B signal (sync tone at 1165 Hz) as OK1DIG calling CQ. His signal was pretty good and between -15 dB and -13 dB. His equipment: 4 x 17 yagi and 1 kW.

I could also see K1SCE answering the CQ (sync tone at 1389 Hz) He used 4 x 9 yagi and 1 kW, but he was not picked up by the other station. The signal from K1SCE was not strong (best -20 dB), but it was perfectly readable at my QTH.

If my SSPA was connected, I would have answered OK1DIG. My first priority is getting on the air - and flying to the Moon!

Best regards OZ1BXM Lars
Homepage: oz1bxm.dk

lørdag den 1. april 2017

144 MHz EME: Graves radar 143.050 MHz heard

Today Friday 1st of April is my lucky day! I've heard the first radio signal off the Moon!

I listened for ham radio signals from the Moon after having erected my 2x6 vertical yagis. I listened most of the time on 144.120 MHz - but no stations were heard. I was disappointed. I had expected at least some stations be visible on the waterfall. The reason - probably - was lack of big gun stations.

The danish ham radio magazine OZ published "Experience EME using simple equipment" in their July 2015 issue. The message was clear: Use the French Graves VHF-radar signal as a beacon, and listen to its reflections off the Moon! The radar is located in 70140 Pesmes, France (locator JN27SI). It transmits a powerfull beam between 15 degrees and 40 degrees elevation. The azimuth angle is between 90 degrees East through South until 270 degrees West. The purpose is to track LEO satellites. As a side effect, the radar signal at 143.050 MHz will hit the Moon and bounce back to Earth.

The map below shows the location of the Graves radar. It is far away from my QTH.

OZ1BXM QTH and the Graves radar in France.
I used my EME station for receiving the Graves signal. My Yaesu FT-847 can easily tune to 143.050 MHz, and when I aimed the antennas towards the Moon, the radar signal (continous wave) was heard immediately and visible on the waterfall.

A screen-dump of the "Wide Graph" waterfall in WSJT-X is displayed below.

Wide Graph waterfall displaying the radar signal.
Kind regards from OZ1BXM Lars Petersen
Homepage oz1bxm.dk

fredag den 24. marts 2017

144 MHz EME - Antennas are up

Spring has arrived in Denmark, and now it's time for antenna work!

During winter time, I've spent much time preparing the new set-up. The antenna mast was resting on the lawn and was easy to access. I've mounted the following items onto the mast:
  • Two new 6-element antennas (Dual PA144-6-2) 
  • Elevation rotor (Kenpro KR-550)
  • Wooden cross-boom
  • Pre-amplifier
  • Power splitter
  • Coax-relay 1 kW
  • Coax cables for RF
  • Control cables
I decided to erect the antenna mast on a sunny day in March. I called a friend to assist me. Two persons can do a safer job than one. My friend was on the roof pulling a rope, which was fastened to the top of the mast. I was on the ground pushing the mast. After some minutes, the mast was erected and secured to the house wall.

144 MHz EME antennas.
Building an antenna system is fun, but it can also be cumbersome. I am very much looking forward to hearing my first EME signals, and I will report my results on this blog!

OZ1BXM on the roof (photo by XYL).
Regards from OZ1BXM Lars Petersen
Homepage http://oz1bxm.dk

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 progressing nicely. 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