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running dogg wrote:
As I understand it, it is the front end transistor(s) that are being overloaded when somebody talks about "antenna overload". This problem occurs mostly with cheap portables. Since they are built cheaply, the front ends are also cheap and do not have the selectivity of a better quality receiver. Clipping a length of wire to the whip of one of these portables will pick up images mostly of AM and FM stations that are in the vicinity of the receiver. For example, I have a cheap Radio Shack AM/FM radio that is easily overloaded. Just pointing the whip antenna in the direction of the nearest FM station (about two miles away) is sufficient to produce images of that station all over the dial. The problem is not with the whip, it is the front end. Correct, which includes the first mixer too. Either the front end needs better preselection using some kind of LC circuits and/or the active componants (transistors) need to be operated at higher voltages to provide more 'headroom' from overloading. A good receiver uses both methods in conjunction with well designed RF amp's and mixers'. ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
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