The power supply that came with my old TPLink TL-WR1043ND v1.8 WiFi router wasn't exactly too interference-free either. Only years later did I realize that the thing did not have a CE mark on it anywhere (it would have been legally required at the time already), and a look inside revealed a lone ceramic capacitor across the line at the IEC jack for interference suppression. That thing turned out to be shrouding my entire PC setup in a cloud of noise that would interfere with reception well into the shortwave range. Even got it replaced when it died (presumably capacitor plague) a few years later. Many years ago in the early 2000s I bought a reasonably fancy metal-cased Fast Ethernet switch from some eBay seller. A few types of trimmer capacitors were problematic long-term. Tuner frontend alignment might be way off. Anything switch-mode is potentially critical. LED lights in particular vary heavily in terms of EMI, some are dead quiet even on AM (I suppose little more than a capacitor dropper power supply) but some LED drivers have been found to be impeding radio reception even beyond the FM band (not just wiping out the AM bands as is more usual). You may have some interference sources near your antenna. In urban areas with a crowded band, overloading of the receiver can be a real issue. It also helps not to have a POS for a choona. 1990 and may have been some kid's first "hi-fi" at the time.Ī dipole antenna is something for people who live at most a few dozen miles away from some reasonably strong stations. As it is very much enthusiast territory though, you must get the basics out of the way first.Ĭlick to expand.You don't mean the cheap-looking compact stereo pictured above though? That thing is ca. TIC is a good source for FM tuner related info, along with the associated FMtuners group. This makes it easier to get away from domestic interferences sources as well (or, conversely, a handy tool in identifying those). (I mean, I have pulled in stations something like 1500 km away at night with a lowly Technics SA-GX100 receiver in the past, but it wasn't the last word in selectivity.) You may have better luck finding a decent portable radio for AM purposes, especially if aided by an external tuned loop (e.g. Of the FM/AM tuners you are going to find, a lot will be quite mediocre on AM. A highly directional FM antenna would generally be placed on a rotor and rotated remotely instead. AM loops are generally placed in reach of the user for orientation purposes. I believe a bit of searching may well turn up a disused 3-element somewhere, maybe even something fancier (don't confuse with old TV antennas though, even if a combination wasn't too uncommon). They are commonly placed on the roof (with adequate lightning protection) or at least in the attic as a result. Expect unbalanced outputs at up to 3 kOhms of output impedance (so decent audio cable shielding and non-excessive length required), typically 750 mV out for 75 kHz of deviation on FM.įor an FM antenna - even a basic dipole - to have its intended directivity, it must be placed as freely as possible, substantially away from anything metal or solid walls. Your average choona is not going to have any digital outputs, we are talking a technology that peaked in the '80s and early '90s. Hence why a compact stereo such as the one pictured above is going to have two antenna inputs - one 75 ohm coax which will take a dipole or Yagi and other such FM antennas with a balun, another being a high-impedance balanced input that takes a loop antenna for AM (which needs to be the same inductance / capacitance as the one supplied as it's usually part of a tuned circuit that is tracking the reception frequency). The bands are literally two orders of magnitude apart in frequency and correspondly, wavelength. There is no such thing as an FM and AM antenna.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |