It Seems To Me—By John Peterson, KG5ZA I was sitting here contemplating the changes that have occurred in our hobby over the last twenty years. Many of them of such a magnitude as to boggle the mind and even shake our beliefs. In the length of time that I've been a licensed ham, I have seen vacuum tubes relegated to the shelf as an item of curiosity. Solid state has progressed from the use of discreet device to IC's, and circuit boards have gone from rather large easy to work on things to surface mount, which seems to require something more than 20/20 vision to work on. When I first became interested in Amateur radio, novices were still limited to CW on the HF bands and most rigs of that day still included AM operation. Now many rigs don't have AM as side-band has become the mode of choice for voice operation. This is due in part to the need to make the best use of the spectrum (less band width). I have been wondering how long it will be before we start seeing cw disappear from our rigs. If the ARRL is successful in the passage of their new proposal I feel that it will be the beginning of the end for cw. This is not an altogether bad thing, but. Well that's enough from the soap box for now. I am including brief instructions on how to work AO-27. This is one of the so called "easy sats" and many have worked it with nothing more than a hand held duo-bander. The following is written by Mike Gilchrist KF5FDJ of Fort Myers Fla. Mike is the AMSAT Area Coordinator.
A gain antenna for 70-cm is usually required; a stock rubber ducky will not be adequate. I have had limited success with a long, wispy dual band 'cat whisker' type gain antenna. If you use a car body or another piece of metal as a reflector, you will increase your chances of working the bird. In any event, whichever antenna you use will have to be rotated to best match the polarity of the bird. Experience shows a vertical orientation at the beginning of the pass, to nearly horizontal mid pass works best. AO27 is a polar orbiting satellite, meaning the orbit of the bird takes it nearly over both the South and North Poles. Software controls the amateur radio payload, which toggle the satellite on during passes from north to south, and only during daylight passes. The satellite turns on several minutes after entering daylight, and stays on for another several minutes. Because of these limitations, the bird is only usable by operators in the Northern Hemisphere, and those close to the equator B ONLY during daylight passes. Operators should understand that this satellite is seldom vacant, and if you can't hear it, DON'T transmit. You will only cause QRM to other operators, and sully your reputation. AO27 has a very sensitive receiver, and I have managed to hit it with 100 mw of power at times. Since AO27 is a very busy satellite, especially on holidays and weekends, a portable operator will most likely have limited success, unless they use a multi-element gain antenna for the uplink and downlink. I have also found use of a preamplifier beneficial for hearing the bird well, and knowing when to jump in for a contact. Most QSOs are short, contest style exchanges, including grid square, first name, and city. This sort of contact maximizes use of the bird for the scores of operators who might be trying. Weekend passes, to the uninitiated, sound a bit chaotic. There is a culture, which exists on the bird, and my best advice is to listen to a couple passes, and model your operation after the successful operators you hear. AO27 is a full duplex bird, meaning that you can listen to the downlink as you transmit. If your rig is capable of full duplex operation, fine, otherwise half-duplex operation works just fine on the FM birds if you program the frequencies in your HT correctly. You should program your HT with 5 frequency pairs for working AO-27. Start with the first pair, using a non-standard split, and tune to the next one as the pass progresses.
Downlink - Uplink |