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From: Andreé (andree.knott@t-online.de)
Date: 12 Sep 2002
Time: 01:13:57
Remote Name: 195.145.17.162
Easyer and less expencive than ordering a big package of ferrite beads would be feeding your TRX with "noiseless" DC-power. Perhaps your Kenwood accepts 12V. The noiselessnes of your cars battery will be guaranteed. If you switch off your mains house wiring at the main switch (we have such a switch for every appartment here) all local homemade noise should be switched OFF. If you switch the mains on again, line by line by the circuit breakers, you might find out the source (if it is inside your house). But this possibly does NOT show you how to avoid this noise flowing or radiating towards the antenna. Additional: Before you buy these ferrite beads try a bundle of four to six ferrite rods (taken from old AM radio sets, I always collect these, *) you might have in your rf-parts stock and wind the coaxial feed line(towards the Isotron) around it. I used 6 ferrite rods and wound about 10 turns, side by side, fixed them with some tape. The best place to insert such a choke might be a quarter wavelength before the cable reaches the antenna (because I suppose the Isotron uses the feedline as a counterpoise). If the feedline is bundled with other feedlines or fixed together with other feedlines at the metal structure of the tower, maybe it would be the best to seperate it for a while and take away the other feed lines to find out what is really going on. If you have enough ferrite rods (*) add such a choke into the mains line of your TRX. These chokes isolate a noise source that the noise is not able to flow along the line anymore. If this isolation works, because the noise really is flowing along the feedlines and is NOT radiated and if you use several parallel feedlines you have to isolate EVERY line with such a choke. This may be some effort...