At 07:06 PM 07/31/08, you wrote: >...Or two FM stations 1.6 mc. apart. We've had this problem on 2m >with two stations 600 kc. apart. > >With FM stations the intermod product is far wider than the IF >bandwidth of your receiver, so it isn't much of a problem until <both> >stations are silent, such as between words/sentences. It can make for >a tough-to-find source. A spectrum analyzer and beam can be useful to >*see* the intermod product to help find the source of mixing. > >Laryn K8TVZ
When the 220MHz repeater band was first getting started in Los Angeles there was a local gentleman that was importing Midland 13-509s - Bill DuHaime, WA6NTW. I suspect that 90% of the '509s in southern California went through his garage at one point. He used to sell them with 223.5 simplex, 223.0 simplex, 223.94 (his box), and he sold crystals for 223.98 (the ARES box), 224.94 (the Mount Wilson box) and a few more. He had built up the 223.94 repeater from a high band RCA 500 receiver, a 13-509 transmitter backed off to 5 watts and a homebrew 60 watt tube PA deck. People were amazed that a 509 mobile could live with a duty cycle that approached continuous keydown from 4pm to 8pm every day. Anyway Bil invited me to a coordination meeting, and it turned out to be the first 220MHZ coordination council meeting after 220 split off from one of the other councils. One comment made at that meeting, by a very well known broadcast engineer, was that 1.6 was absolutely the worst choice for 220 repeaters. He commented that 1.6 was the most common co-tower spacing for FM stations across the country. He said that 1.4, 1.5, 1.7, 1.8 anything would have been better than 1.6. I have no idea if that was or is true but if so, then it is an interesting bit of trivia... Mike WA6ILQ
