tirsdag den 6. marts 2018

Getting ready for AO-92 mode L/v

The satellite AO-92 was launched in January 2018. It carries an U/v transponder (uplink UHF, downlink VHF). One day in the week (usually Sunday) AO-92 runs in mode L/v with uplink 1267.350 MHz, and downlink 145.880 MHz.

I would like to operate AO-92 using the L-band uplink. I own some 23 cm equipment, which is unused right now, and can be put into service. Here is my concept of mode L/v:
Equipment for working AO-92 in mode L/v.
The upconverter is MKU 13 OTX from Kuhne Electronic. It converts 144 MHz to 1268 MHz at 1 W. The upconverter is keyed by injecting a DC voltage into the coax-cable.

The 20 W PA is based on the power module RA18H1213G from Mitsubishi. I bought the PA as a kit from PE1RKI Bert. You can find the circuit diagram and a description of the building process here.

The low-pass filter removes harmonic waves, and monitors the RF power.

The antenna is a helix-antenna for circular polarization (RHCP). As the AO-92 antenna is linear, there will be 3 dB loss when circular polarized waves are received by the satellite.

The 23 cm equipment is housed in an alu-box which is mounted near the antenna.

My 23 cm equipment in the alu-box.
I am looking forward to next Sunday where the L-band uplink is active. I hope to get some contacts via AO-92 in mode L/v!

lørdag den 10. februar 2018

Yaesu FT-847 Doppler Control with PstRotator

I want to work amateur radio satellites, especially those with a linear transponder (SSB/CW). I worked satellites about 10 years ago, but the urge to do it again has appeared. As I have never been able to control the doppler shift, I wanted software for this task. 

The program PstRotator can manage both antenna tracking and doppler correction. However, the configuration of PstRotator was more difficult than anticipated.

The software runs on my PC under Windows 10 Home (64 bit). PstRotator and OmniRig are installed as usual. Hardware and software is connected as shown in this sketch:
PstRotator controls the rotators and the FT-847 transceiver.

OmniRig is a driver for COM-ports. It enables several programs use the same port. This is a benefit, because a log-program often needs access to the same COM-port in ordet to read the transceiver's frequency and mode.

PstRotator is like a "Swiss army knife". It controls both the rotators and performs doppler correction. 

My rotor controller is ERC-3D. It controls both azimuth and elevation. ERC-3D was made by DF9GR, but the controller has been removed from the market and is now obsolete. It is replaced by the ERC-M

ERC-3D rotor controller by DF9GR.

If you would like a detailed description how I configured PstRotator and OmniRig, you can find a PDF-document on my homepage: oz1bxm.dk/PstRotator.pdf

73 from OZ1BXM Lars
Homepage: oz1bxm.dk

mandag den 1. januar 2018

Yaesu FT-920 no transmit

I was surprised when my Yaesu FT-920 HF transceiver suddenly stopped transmitting. RX was ok, but no TX in any mode.

I began checking the backup battery and performing a master reset. This advice was given on eham.net by KB5UBI: "A full reset did not solve the problem, but a button battery replacement followed by a full reset solved the problem".

I removed all power and all cables from the transceiver. Then I removed the bottom cover. I located the backup battery and measured the voltage to 2.32 volt. Then I switched off the Backup switch (next to the yellow capacitor) and replaced the battery (CR2032). Then I swithced on the Backup switch. The voltage of the new battery when fitted was 3.13 volt.

Yaesu FT-920 backup battery.

My Yaesu FT-920 now performs normally. Replacing the backup battery and performing a master reset did the trick!

Happy new Year 2018 from OZ1BXM Lars

Homepage: oz1bxm.dk