Hi fellow Hams, I'm J.B.Young III . KJ4JAE. My work has recently been menchaned in the international magazine Monitoring Times, specifically in the column Below 500 KHz, by Kevin Carey, WB2QMY. December 2009 issue. My work should also soon be up on Renato Romero's site:http://www.vlf.it/ I'm sharing this with you, because I was recently in the hospital and almost died. I have years of work on this project and don't want my work to be lost. My attempt to publish a book on it has failed. I only wanted to recoup some of my R&D costs, but looks like I better go public now. The Schematics I've included (thumbnailed) are my property (Empire CO.) but I am sharing them to all who want to build the circuits as long as noone uses my designs for their own financial gain. Feel free to copy the circuit diagrams to your computer or hard copy them so you can distribute them to other hobbiests. These circuits are strait out of my notebook (scratch pad) and are drawn by my own hand. the writing is not the best, since I usually scribbled in a hurry, excited about doing more experiments but having the desire to record my efforts. For years now, I've been experimenting (allong with many other hams) with trying to transceive through the ground. A lot of people are familiar with the VLF signals that cause currents to flow in the ground beneath our feet. Some of these signals are man made, and some of them are naturally occuring, such as 'Sferics and the famous 'Whistlers' believed to be caused by lightning. These signals can be recieved with loop antennas in the air, other antennas, OR can be directly tapped into by sticking copper probes into the ground, a few feet apart and connected to a vlf receiver, or even a high gain audio amp! (filtered to take out 60 Hz power line buzz). I wanted to see if anyone who frequents QRZ, was in to this sort of thing like me, and share all my knowledge about it. The receivers are simple, see first attachment. All you need is an op-amp, a LM386 N-4, 8 ohm speaker, battery, and two ground probes along with a handful of resistors and caps. No need for an a.m. demodulator circuit, the audio amp will do that for you through the process of auto-rectification. To transmit through the ground isn't as easy. A lot of people believe it's impossible to achieve (at least, with any distance at all) and have given up. I know a ham who buried an antenna and transmitted at 1 Kilowatt and could receive the signal only a few FEET. However, they were going about it the WRONG way. I also tried for a long time to transmitt with only one rod poking in the ground, could never make it work. UNTIL I tried sticking 2 rods in the ground a very wide distance apart and hooked the output of a high voltage/low current audio amp I homebrewed to them. THEN the signal traveled very far. For instance, my current transmitter delivers about 170 Volts (peak to peak) to the two poles, the signal is an A.M.modulated carrier at 17 KHz. The poles, which are copper pipe, are about 300 feet apart and go about 3 feet into the ground. I can pick up the signal with my receivers up to about 1/4 MILE away! I hav my portable receiver in a nice handled case and hook the two receive probes to it through an earphone jack. The poles on the receiver need only be placed a short distance apart (about 3 feet). The farther the tx poles are seperated, the farther the signal will transmit. Same thing for the receivers, put more seperation between the ground rods and the more sensetive the rx becomes. My first several transmitters were just audio amps, they put only audio into the ground. Although I could pick up the signal a good distance, it was always badly distorted. I always play a c.d. player with music into my transmitters when experimenting, unless I have someone else around that can speak into a mic (which is not very often). I couldn't understand why the transmision was garbled, when my Tektronix O'scope showed a perfectly clean signal with the ground rods attached and the tx running. So I decided to make a tape of me generating various audio tones, speaking the frequency over the tape, starting at 300 Hz and going to around 20 KHz. I softly spoke each frequency in between each change. I went out into field around my house to listen... The audio tones came in clear but my speech again was GARBLED. UNTIL the tape reached the 8 KHZ tone. For some reason, when I made the tape, I spoke "Eight KiloHertz" WHILE the tone was running, instead of before I generated it. While standing there in the field, I heard for the first time, crystal clear voice come over my receiver. I was breathless... Then I repeated the experiment over and over, wondering why my voice could only be understood with around a 5 to 20 KHz tone RUNNING IN THE BACKGROUND. (Anybody figuring this out yet?) It took me a while, but I theorized that because of velocity factor (the fact that r.f. travels at different speed based on frequency through conductors) and other factors, that since speech and musics' frequencies vary over many octaves, that the individual waveform componants were arriving at my antennas at different times and out of phase/sync. Based on this theory, I thought to myself. If I only transmitt a SINGLE frequency and A.M. modulate it, it should work. After all, that's EXACTLY what my audio amp had done in the first place. When the 8KHz tone was transmitting and I spoke, my voice was being linearly mixed with that signal by the amp. In other words, my voice was "riding the back" of the 8KHz sinewave much like an A.M. carrier I then constructed an A.M. Modulator using the XR-2206 chip, amped the output up from about 2 volts peak to peak to around 170 at 17 KHz, and the rest is history.... It's now been several years since I finally completed my first two fully functional Underground VLF Transceivers and had my first underground QSO, between me and my neighbor across the street. On Monday 9-18-06 I saw the ultimate success of my efforts. Using 4 copper rods hammered into the ground about 3 feet, (2 in front of my house and 2 in front of his) with a seperation between mine of 40 feet and his 20 feet AND over 200 FEET between the two independant systems, I had the pleasure of talking to another person THROUGH THE GROUND with crystal clear sound and LOUD modulation. I have included the FULL schematic of the final transceivers on the last thumbnail. Theorectically, this sytem will go as far as you want it too, you need only seperate the poles farther apart. The system appears to go about THREE times as far as the poles are seperated. You want a range of 6 Miles? Seperate the poles by 2 miles. This sounds VERY impracticle, but there ARE uses for such a system. Suppose you wanted to have a covert 2 way intercom between two houses seperated by a river.... or seperated by a street like my neighbor and I.... Radio can be eavesdropped on, a wired intercom would be impossible because of the river or street, you get the picture. Besides it's FUN!!! I hope there will be lots of comments and interest... To answer some questions beforehand, I use the untuned wideband audio amp as the reciever, with a high pass filter of around 300 Hz, so I can listen and demodulate any signal I detect from 300 Hz to around 400 KHz. I have monitored NDB's and just bout anything else you can imagine in that frequency range. The 100 KHz LORAN C, should be the first thing you hear when turning up the gain pot on the receiver. Using a tuned A.M. receiver seems to do nothing to increase the range, I've already tried it. I used a Palamar VLF converter with the ground probes feeding it, and the converter plugged into my AOR 8200 tuned at 3017 KHz (listening to 17 KHz) and have almost the exact same range as with my hombrew receiver. The second attachment shows the receiver with a .01micro Farad cap shunted across the input, and a .22nano Farad cap between the receiver and ground rod. The first cap stops signals above 400 KHz (namely A.M.Broadcast Transmitters) and the second cap provides a highpass critical frequency of 30 Hz, this makes the receiver start amping max at 300 Hz (Critical frequency times 10) which reduces power line buzz at 60 Hz and asscociated harmonics to an acceptable level. I've also included the XR-2206 schematic for an A.M.modulator for connecting a c.d. player or microphone circuit (also thumbnailed) that forms the basis of an A.M. Transmitter that will go from about 10 Hz to 1 MHz. The XR-2206 can be bought from Unicorn Electronics for about $3, and the TL082 is about 30 CENTS (also bought the LM386N-4's from them for about a Dollar a pop. I'm interested to see some reponses and make contact with other experimenters. Have fun (I have!) -73's.