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![]() also check their fundamental and see if you can detect the fm on it, that should be obvious enough also and something you could go demonstrate to the engineer that may show him they have a problem that developed after their certification. Bingo, I just went to thier fundimental and in FM and WFM I can understand the radio perfectly ... Nice and clear. Weirdness. Scotty W7PSK. |
#22
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On Wed, 24 Jan 2007 17:50:56 -0800, "RST Engineering"
wrote: Because he's got a SINGLE frequency interfering with his station. He reported a single frequency, that does not limit the problem to a single frequency. I already explained that. Care to calculate the order of filter that will do 80 dB as a low pass filter? That is not particularly difficult, quite common in fact. Standard engineering syllabus teaches us that you enjoy a 6dB/Octave or 10dB/Decade roll-off for each reactive element in a filter. I already suggested a 6 or 8 pole filter which brings us up to your 80dB for an entire band, much less a single frequency. Slam dunk simple. I am quite sure that many here that are experienced in actual bench work would nod in agreement that the better part of a project is building the things around the electronics - like an enclosure, connectors and such - than with the electronics. 8 off the shelf items (actually 4 pairs) vs. 2 with one of the two needing to be variable AND tuned? Is that such a major demand on the bench skills of an amateur radio operator? And the Q of the components necessary to make the insertion loss negligible at 160 meters? For receive? C'mon now. And 160M instead of the band he is interested in, 80M? Anyone can contrive to fail, that's plug simple. The next set of restrictions will have us going down the garden path to build a crystal lattice filter for the sake of unneeded astronomical Q and to achieve spectacularly low insertion loss - turn up the RF gain. The issue is moot with the probability the issue revolves around spurs from corroded, weather beat connections. I have a buddy who suffered identical issues from an AM station 1 mile away. He wire brushed poor joints and solved the problem that filters couldn't solve. 73's Richard Clark, KB7QHC |
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