It’s official, Southern California Special Olympics is back, and we will be needing communications volunteers. When I got started on this event, I volunteered because Henry WA6RJA was asking for help. We were out there at 5:00am (we are not that early this time) so I was drowsy. I was the new guy so I was at a position that didn’t have much activity and I was leaning against a post waiting for something to happen. Someone poked me in the back and startled me, when I spun around it was one of the athletes. She had her gold medal, an ear to ear grin and was showing it to everyone whether she knew them or not. I was hooked from that point on. This even is very important to them and I enjoy being a part of making it happen.
The dates are November 12-13. Time 8:00am to 4:00pm at the fountain valley recreation center. Our trailer will be just to the north of the parking lot. There is a road between the parking and the golf course and we are past the tennis courts. Operating frequency will be 146.235+ 100 ctcss. Last time out we had one volunteer, so we really do need help to put an effective team out there. In addition to being a worthwhile community service, it is also good training for emergency operations.
The location is 16400 Brookhurst. The yellow pin will be our approximate location.
Venues will be: Golf
Volleyball Soccer Softball Tennis Medical Games HQ Honored Guest Family tent Information Net Control
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Repeaters are often a mystery. Strange mythical boxes on a mountain somewhere that echo your voice over larger distances. Recently there have been a number of posts from hams wanting to use cheap HTs linked together with a VOX circuit to make a repeater. There is really more to them than that, and good reasons for the additional equipment that really shouldn’t be ignored.
There can be a lot of variations in what a repeater looks like, depending on what models are used. This photo is fairly typical.
At the top is the power supply. It is 100 percent duty cycle so that heavy use does not burn something out that would be a project to replace on a mountain top.
Next is the repeater itself. This one has cards for the receiver, transmitter and the control logic. Also common would be two good quality radios interfaced to a controller. The quality of the radios is important since repeaters are usually up where they have a view over a wide area, which also means that the receiver will get hit will signals from a wide area that they must reject. The receiver must also be able to reject the signals from adjacent repeaters which may be putting out very strong signals. The transmitter should also operate clean so as not to interfere with people in the view.
Not seen in the picture is a circulator which serves two purposes. First is to protect the transmitter from reflected power if something should go wrong with the antenna. The environment on a mountain top can be quite rough on equipment. Below is a dish that came off of Heaps Peak. Second is to keep other signals from going up the line in to the transmitter finals and causing mixes.
Down at the bottom are the cavities, 2 meter is this case. They are tuned to the transmit, or the receive frequency to keep the transmitter for interfering with the receiver allowing the repeater to operate full duplex. They also help reject other signals outside the intended operating frequency. On the left is the spectrum analyzer used to tune the cavities. To the right are the cavities for a 220 repeater.
There is also lightning protection and grounding to protect it from the inevitable strikes. The controller is responsible for the ID, optional features, and remote shutdown in case something goes wrong.
This is a basic ham repeater. There is not much that is non essential in it, so this is something to think about when someone is tempted to cut corners. Commercial systems are often more complex that this, using LTR Trunking, or Digital Trunking to provide additional features and to better utilize the frequencies.
While Amateur Radio operators don’t have a mission yet, and hopefully won’t, we have decided to run an open informal net for purposes of exchanging information and responding to emergency situations should they occur. Control operators will be monitoring as their schedule allows and we encourage other operators to do the same. There is not a need to re-transmit information from the news or internet, especially as we don’t have the ability to validate them anyhow. First hand information or observations could be useful though and much appreciated.
The foot print of our repeater covers much of the Los Angeles basin and down the coast to the south. The frequency is 146.235 + 127.3