A little more progress has been made on my radio problem. I have = discovered that the radio tower is less than 2 miles from here. Also I = hooked up a small speaker to the amplifier and I can hear the radio = station on the seismograph. I tried unplugging the coil and I could still = hear it although it was much reduced. When the pre-amp was unplugged I = couldn't hear it at all. So it looks like the coil is acting as an = antenna for the pre-amp. The cable from pre-amp to amp may also be doing = so but to a lesser degree (it is shielded). I tried several other coils I = have around the lab and they all worked fine as antennae. So I doubt that = another coil would help. A different pre-amp might do it if I could get = one. Do your seismographs have pre-amps? Is there a diagram? I called the electronics company and they are working on it. They seemed = to doubt that shielding it would work since AM is long wavelength. The = guy at Wards is on vacation so I can't get any parts from him for a while. = =20 While I was listening to it, I made some observations. When I touched the = intrument the magnet would move and the radio signal would go out. I = guess the instrument signal overpowers the radio signal when it is moving. = Also, my touching the coil or preamp seemed to affect it too. With the = coil unplugged, I could hear better if I touched the pre-amp. However = with the coil plugged in touching it would often stop the signal. It = seemed very touchy. =20 Anyway, If this gives anyone some ideas, I would love to hear about it. John Tacinelli Earth Science Instructor Rochester Community and Technical College __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>