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#41
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![]() It has just occurred to me that if you can make or get hold of a switched attenuator to stick in between the antenna and the input socket of your remote receiver, you can make very accurate measurements indeed. I am thinking of the type with 8 or 10 switches. The first switch gives 1dB of attenuation, the next 2dB, 4dB, 8dB, and so on. So long as you have some sort of signal strength meter you can monitor on the receiver, you just switch in enough attenuation to give the same meter reading at each test location and record how much attenuation you have switched in at that point. The more attenuation, the better the received signal. That will allow you to determine relative signal strength to within 1dB which is going to be good enough for your purposes. The attenuator can be used for all kinds of projects, so it might be worth taking the time to build one irrespective of what you end up using for a signal source. The usual Google search will turn up construction details, just resistors and switches in a screened box with some PCB offcuts or copper foil to provide internal screening between each section. This is a bit of a challenge to make accurate to 1 dB at 144 or 440 MHz. The leakage around the switches, etc, is difficult to deal with. You're probably better off scrounging for a decent surplus/used step attenuator made by someone like Weinschel or HP. |
#42
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![]() "Cecil Moore" wrote in message et... wrote: What's the easiest method of determining which antenna works the best for a particular situation? Simplest answer is to try it and see (experience). There is lots of experience on this newsgroup from which to draw. Most of us can predict that someone will not be satisfied with a CB whip and autotuner on 75m, for instance. -- 73, Cecil http://www.w5dxp.com ----------- Hey! I heard that! G I was kidding, you know. Due to my certain lack of exposure to operating 75 meters mobile, I would have thought that anything less than a full buck and a half of watts and some horrendously large vertical would have been a waste of time. I guess I have something left to learn after all. Problem is, outside of the R/C Flyers Net, I have no use for 75 meter phone. Now that I'm retired, there is no reason to be mobile at 0600 these days. I'll leave the mobile low banding for those with the need. Ed, NM2K |
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