Magnacast 5000

[Mike(Mont)]

Look at what happens right about 1988.
http://helios.izmiran.troitsk.ru/cosray/months.htm

As for the Scan Gun antenna, I assume it is a coil similar to the VR2000. There is a photo of one on the Mexico Trip page http://www.lrlman.com

Carl, the download instructions on the VR site show how to test the unit.

[J_Player]

Interesting photos, Mike(Mont). After looking at the pictures of the magnacast 5000 and the VR 2000 Mexico trip pictures, It appears that the "Forward Gauss" machines are actually AM transmitters and special receiving antennas that locate places of varying signal strength. In addition to the scan gun, the VR 2000 and magnacast 5000 also contain a loop antenna which looks similar to the antennas used in radio direction finders. The loop antenna for the Magnacast 5000 is a larger rectangular antenna compared to the red square antenna shown on the VR 2000 photo.

From what I have seen in the photos and manual, it appears the "Forward Gauss" methods center around broadcasting an AM radio signal, then surveying the air out in front of the broadcast antenna for signal strength. Presumably, the signal will be stronger depending on the existence of a target in the ground. The two devices used to measure signal strength are the loop antenna, and the "Scan Gun". The loop antenna is probably a simple coil of wire designed to pick up the signal that was broadcast and allow a survey of where the strong signals areas are. The "Scan gun" does not give many clues just looking at it, but I would think maybe it works similar to a RF sniffer that is tuned to the broadcast frequency. Perhaps it performs a functions similar to the loop antenna, but with finer resolution, or maybe it is designed to pick up a RF signal that is to be demodulated.

[Dell Winders]

That would be my wild guess since many of the frequencies used for Frequency Discrimination are within the AM range. Dell

[J_Player]

A closer inspection of the "Forward Gauss" machines shows that the VR 2000 is not using a "Scan Gun" on its receiver, only a loop antenna to pick up the signal. The loop antenna on the magnacast 5000 is apparently the transmitting antenna, not to be used at the reciever for surveying the signal strength. I presume the VR 2000 also has a similar loop antenna for transmitting the signal.

It appears that in the magnacast 5000, the old receiving loop antenna of the VR 2000 was replaced with the "Scan Gun" receiving antenna that was made to be adjustable.

Judging from the use of the Vernell machines, I would suspect the broadcast frequencies to be at the AM broadcast band or lower.

[Mike(Mont)]

I'm still interested in any info people have about the Forward Gauss technology. The Vernell website says the original version was quite successful. I suspect there must be some improvements now with the Magnacast 5000 or else locating conditions are acceptable again?

BTW, I read on a Chinese website that the VR1000B uses 400-3000 Mhz so any AM reception would probably be some lower harmonics. I wonder if one of those spectrum analyzers could be used as a receiver for a DIY system? I guess you would need to know how to build the transmitting antenna or maybe use a walkie-talkie for the transmitter.

[J_Player]

400-3000 mhz is pretty much all of the UHF spectrum. Devices that use these frequencies include UHF television, cordless phones, amateur radio, mobile radios, radar, radio astronomy, cell phones, satellite radio, wireless LANs, and microwave ovens. The problem of building a receiver is you should first get an idea of the receiving frequency before constructing the circuitry and antennas. A quick test (if the actual frequency happens to fall in the UHF TV band), is to use an old-style portable UHF TV with an analog tuner to try to pick up the signal. If the VR1000B sends an AM signal in the UHF TY band, then you should be able to see some video patterns on the screen when you tune to the transmitter frequency. You may even be able to use this portable TV to survey relative signal strength in an area in front of the transmitter. But this works only if the transmitter is sending a frequency that the TV can receive.

Since the "Scan Gun" receiver is only used on the newer Magnacast 5000, I would think this locator uses a higher frequency than the earlier VR1000. The reason is because the "Scan Gun" is physically smaller than the large loop antenna used in the earlier machines, which leads me to suspect it contains a loop antenna to pick up a smaller wave, or higher frequency.

At this point, it may be a good idea to get some help from Carl to test and see what kind of signal the VR2000 puts out. ie: What frequency or frequencies, the radiated signal strength, and what sort of modulation. This information will provide good clues to what kind of receiving equipment would work best to pick up a signal from the transmitter. The antenna design and receiving electronics depends on what frequency, the transmitting technique, and the modulation being used. I would be particularly interested to know if there are any constant or varying lower frequencies being sent as an amplitude modulation signal, possibly in the 500 khz to 3 mhz range.