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AM antenna problems
On Fri, 7 Sep 2012 13:58:38 +0000, ULLS
wrote: I am trying to receive an am signal well below ground level in a metal server room, there is a coax feed up to the roof which I used and attached the standard wire loop that was supplied with the tuner, Numbers please... What make and model tuner? What loop antenna? What type of coax cable? How many feet of coax? The loop antenna that comes with most home hi-fi receivers is resonant in the BCB (broadcast band). If you add coax cable or twinlead to the loop, it becomes detuned and starts looking more like a short circuit. The barrier strip BCB connections on the back of the hi-fi are intended for a "long wire" antenna, and a decent ground connection. The required BCB antenna impedance is probably much higher than your coax cable, which means you'll need to build a matching network if you plan to use coax cable to the roof. You might do better with just the longest wire you can find that makes it up to the roof and beyond, if it doesn't pickup RFI/EMI from the servers. If you're plugged into the "F" connector found on the back of some hi-fi's, that's for FM band reception, not BCB. however when I attempted to tune into some stations I could only pick up a couple of local stations and wasn't able to receive the ones I was hoping for. That's because the loop antenna is acting more like a short than an antenna. when I dialed in the desired frequencies, Why would you want to hear BCB AM radio inside a server room? all I was receiving was a tone, the tone changed in frequency/pitch depending on the tuners frequency. If it's anything like the server farms that I occasionally visit, the RFI/EMI from the high power switchers, servers, and thousands of clock oscillators is sufficiently high that I couldn't even get a pair of cheap FRS/GMRS radios to communicate across the building. I suggest you consider streaming audio as a better alternative. To check that I could receive the stations I took the tuner to the roof and attached the antenna directly and sure enough I could pick up the desired stations. Yep. You probably connected the loop directly to the unspecified model radio. Try it again with an approximate length of unspecified coax cable and it should fail similarly to your indoor test. Also note that you're now outside what I suspect is a shielded room, which should improve reception. For entertainment value, try making a cell phone call from insider the server room. My thoughts are that the coax is affecting the signal in some way, perhaps picking up electrical noise? Yes to both questions. any advise would be appreciated. Long wire antenna or switch to streaming audio. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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