rjr@mgweed.UUCP (Bob Roehrig) (09/18/85)
To answer Steve's (possibly some others as well) question on VLF, here are the basic rules as quoted from Part 15 of the FCC Rules: 15.111 OPERATION BELOW 1600 kHz: A low power communication device may be operated on any frequency between 10 and 490 kHz or between 510 and 1600 kHz subject to the condition that the emission of RF energy on the fundamental frequency or any harmonic or other spurious frequency does not exceed the field strength in the following table. Freq (kHz) Distance (meters) Field strength (uv/meter) 10 - 490 300 2400/F (kHz) 510 - 1600 30 24000/F (kHz) 15.112 ALTERNATE PROVISIONS FOR OPERATION BETWEEN 160 AND 190 kHz: In lieu of meeting the requirements of 15.111, a low power communication device may operate on any frequency in the band 160-190 kHz provided it meets all the following conditions: (a) The power input to the final radio frequency stage (exclusive of filament or heater power) does not exceed 1 watt. (b) All emissions below 160 kHz or above 190 kHz are suppressed 20 dB below the unmodulated carrier. (c) The total length of the transmission line plus the antenna does not exceed 15 meters. -------------------------------------------------------------------------------- One publication dedicated to VLF experimentation is called "The Lowdown". It is a monthly publication and the cost used to be $10/year. There have been some real DX contacts made on the 1750 meter band, I am told. Some stations have worked several hundred miles. It appears that the only way to get a decent signal out is to use a vertical and lotsa radials. Antenna efficiency is poor, to say the least. 15 meters (50 feet) on 1750 meters is about like trying to use a 2 meter whip on 160 meters! The only commercial manufacturer of transmitting equipment that I have seen is Palomar. They also make a receiving converter. Surplus ARC-5's and some other surplus VLF receivers are also popular. With a 15 foot loaded vertical mounted on a 50 foot chain link fence, I have been heard a mile away (not very impressive, huh). There are supposedly quite a few experimenter's "beacon" stations on at night and weekends, but I have never heard any myself. "Call signs" usually are the experimenter's initials. DO NOT USE AMATEUR CALLS THERE! Because there are megawatt stations on this band in Europe and the USSR, one must pick a frequency carefully to avoid getting clobbered. Shielded loops, loopsticks, and some active (whip) antennas are the best for receiving. Bob K9EUI
bill@videovax.UUCP (William K. McFadden) (09/20/85)
You can also get 1750 meter transmitters/receivers/transceivers in kit and finished form from: Panaxis Productions P.O. Box 130 Paradise, CA. 95969 (916) 534-0417 Bill McFadden Tektronix, Inc.