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307
| | Posted on Friday, November 30, 2001 - 9:03 pm: | 
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AS-100 Automatic Radio Switcher
I sure like the Idea of having one antenna on my roof and having two CB radios in the same house. I am the kind of person who has a radio in the "Radio Room" and also has a CB in the living room. The problem with this type of setup using one antenna is that you must have an antenna switch box near one of the radios and then you must remember which position that you last left it in. If you left it in the wrong position, you either have to get up off of the comfy couch or burn up a radio trying to talk on it. Well there is a new Item out that Copper Electronics is now carrying called the AS-100. The AS-100 is a small black box with a lot of circuitry inside that will automatically select the radio that you are using at the time. It is so easy to install and can be done in less than 5 minutes. All you do is put up one antenna, run the coax inside the house or car for that matter, into the AS-100. Then add a coaxial jumper from one radio to the input of the SA-100. All that is left is to run another coaxial cable from the other radio to the AS-100. That's it. The AS-100 has a sophisticated circuit that actually "sniffs" the RF output from the CB radio that you are talking on and using an RF to DC conversion, switches in a small relay to correct the path from the current CB to the antenna. The switching is so fast that you can't tell it even happened. The input/output impedance is 50 ohms so the SWR stays exactly where it was before you even hooked it up. The AS-100 has a maximum input wattage of 100 watts, so it takes the power of most of the everyday CB radios. The AS-100 has a very wide frequency bandwidth so in a sense it will work with all of the export models as well. One of the questions that are brought up when using the AS-100 is "how much power do I lose to use it?" Well the answer is indeed a good one. The amount of power that is used is less than 0.2 dB of insertion loss. That means that the amount of power you will lose will not be noticed. The case of the AS-100 is a black anodized and looks very attractive mounted in the radio room. It is small in size also, about 2.5 inches by 1.5 inches and about an inch deep. Two small screws that are inserted into the flange on the top of the rear panel accomplish mounting. The case is also a tight fitting case so that the RF is locked inside and will not "bleed" outside. This is very important if the two radios are to be mounted side by side. The circuitry of the AS-100 is quite simple. Each side or input of it has its own internal "keying" circuit. The keying circuit is built up off several diodes and a transistor. The RF is sent into the keying circuit and converted to DC. After the DC voltage reaches the relay, it is "latched" into the proper position of the input so it is routed to the antenna. This is a really great idea because now you can simply grab the microphone and key it up not having to worry about where the antenna switch might be. Another great feature about the AS-100 is that it is the BEST tool to have on the bench when testing two radios side by side into one power meter. It makes trouble shooting a radio a snap because you can take readings from one to another without the hassles of always having to unhook the antenna every time you need to make a measurement. I am going to get a couple more of these little jewels and experiment with them in other CB related applications. I will keep you posted as to what I come up with. |
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