Johnson's Techworld

 The Government of India is launching a month long program to highligh the remarkable achievement of the country's space mission to inspire the nation's youth. We the radio amateurs, especially the LEO satellite operators, should take it as a great opportunity. We should also participate in the month long celebration with maximal number of contacts on LEO satellites. We should also strive to get an amateur radio satellite from India, sanctioned by Indian Space Research Organization. The theme for this year’s celebration is “Touching Lives while Touching the Moon: India’s Space Saga,”. It should also be an opportunity to bring more and more radio amateurs on LEO satellites. Most newbie radio amateurs are stuck to VHF repeaters with a handy. They should be made aware that they can use the very commonly available dual bander hand held radio for communicating through Low Earth Orbit Satellites. While a VHF repeater can reach their signals may be a maximum of a few hundred kilomete...

 This the 555 timer Integrated Circuit with which we used to make Code Practice Oscillators when we were short wave listeners to practise Morse Code while preparing for the Amateur License Examination. In those early days of integrated circuits, it was mind boggling to think that this tiny device incorporated the equivalent of 25 transistors, 2 diodes and 15 resistors! Remember that we were just coming out of the bulky vacuum tube era. 73 de Jon,  VU2JO

 Folded dipole antenna was a common sight on roof tops, as the driven element of TV antennas a few decades back. In a folded dipole antenna, a half-wave length conductor is folded into a longitudinal loop and fed at the centre. It has a higher impedance of around 280 Ohms compared to the 70 Ohms impedance of a horizontal half-wave dipole antenna. Hence while a coaxial cable is suited for a horizontal half-wave dipole antenna, a twin-lead transmission line with about 300 Ohms impedance is used for a folded half-wave dipole antenna. 73 de Jon,  VU2JO

 Supplier of one commercially available multi-band 40-10m delta loop antenna has mentioned that it cannot be operated by a coaxial cable. Any parallel wire feeder can be used to operate on 7 bands using a tuner. They have also mentioned that best results are achieved with a symmetric tuner , but any other tuner with a balun also works well. Others have used coaxial cable with 4:1 balun for multiband operation. There are also descriptions of shortened delta loop antennas for those with space constraints. Commercial options for 3.5-54 MHz and kW range rotatable ones could be seen as mentioned online . 73 de Jon,  VU2JO

  Google Meet tomorrow at 11 am IST (UTC+5.30). Please use this link to join: https://meet.google.com/wgz-bjpx-prr Initial presentation by VU LEO Satellite operators. But all Radio Amateurs interested in LEO Satellite Operations can join and contribute to the discussion. 73 de Jon,  VU2JO

 Every radio amateur knows about CQ calls and I am quite to happy to hear a CQ call on the amateur radio bands as that is an opportunity to start a contact. Going back to the history of CQ calls, I was surprised to learn from Wikipedia that it started in the transatlantic cable and landline telegraphy, not among radio amateurs! If 'K' is transmitted after the General Call, it is an invitation for any of the hearing stations to call back. It is also mentioned that it was being used by diplomatic, press, maritime, aviation and law enforcement services till those services discontinued the use of Morse telegraphy. CQ calls have been mentioned in publications as early as 1871. 73 de Jon,  VU2JO

 Here is a video demo of how I work an amateur radio satellite using my fixed elevation azimuth antenna from within my shack. As I do not have an azimuth-elevation antenna rotator, I can work only about half of a typical pass of satellites, mostly those with a higher power output like Amateur Radio on International Space Station and LAPAN A-2 or IO-86 which have an output of about 5 Watts. The cubesats with power in the range of a few hundred milliwatts are difficult to work, though I used to have contacts on TEVEL series before they started re-entering Earth's atmosphere. Occasional contacts on SO-50 and AO-91 have also been possible, though not on a regular. PO-101 has been difficult, though I have been able to hear others and sometimes others have been able to hear me. Most difficult is of course the PocketQube SO-121 which is much smaller in form factor than even the CubeSats. Simple way of course, is to go outside with a dual band hand held radio and point it along the directi...