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#11
September 4th 06, 12:58 AM
posted to rec.radio.shortwave
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Question about the Timewave ANC-4
Ron Hardin wrote: wrote: I have the ANC-4 (original JPS version), which was a great help with random wire antennas. It seems to be of no use with my welbrook. I tried to use the built-in noise antenna on the ANC-4 to make a null with my Wellbrook and never managed to get that to work. Of course, the Wellbrook is a very quiet antenna in the first place. It works fine with mine, using a wellbrook ala1530 and an active whip (or another wellbrook 1530). I don't think the built-in noise antenna is likely to work though. I tossed mine out. OK. I'll try an active whip. Still, I think the built in noise antenna should work. It was fine when I was cancelling local computer noise. With a wellbrook loop and a whip _located right near it_ (near means fraction of a wavelength), you get the same pattern as with two whips separated by a quarter wavelength, but without using any real estate, laid out in the plane of the loop, ie. a double null at one endfire and a max at the other endfire, opening up to a V and sweeping to a double null at the opposite endfire and max at the other. Two loops separated by a quarter wavelength are handy for some things, like nulling in advance a particular station, and then nulling another altogether with the ANC-4, without having to go to multiple ANC-4's. There is an odd thing with two loops, though. For nulling a station by phasing, paradoxically, you should put the station near the max of the loop, not the null. The phase of the signal from the loop gets more and more unstable as you approach the loop's null, and harder and harder to phase out with the ANC-4, is the reason. It's comparatively easy near the loop's max. -- Ron Hardin On the internet, nobody knows you're a jerk. |
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