Through-Ground Radio. (Below 500 KHz)

Discussion in 'Homebrew and Kit Projects' started by KJ4JAE, Dec 30, 2009.

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  1. KA7FTP

    KA7FTP Ham Member QRZ Page

  2. KJ4JAE

    KJ4JAE Ham Member QRZ Page

    Andy, yes I believe it was you and your website. I can remember on the site that the author had "given up" on transceiving through the ground and switched to monitoring natural VLF signals.

    I also enjoy monitoring these and am always listening for anything else and, like you, have dreamed of hearing someone else or even making a contact with someone else doing the same thing.

    I have my theory, but am not 100 % sure why I could never get strait audio or voice to come in without distortion and garbling.

    My receive amps were almost perfect and with the gain wide open could pick up and loudly play music or a tone in the 15 MICROVOLT range!!

    I soon found that this much gain was not needed, as the qrm in the ground even after much filtering was much stronger than this, so I switched gears to building the most powerful transmitters I could.
     
  3. WE0H

    WE0H Ham Member QRZ Page

    Hey John,
    I used to own a 3586C SLM. They are nice as long as they don't have issues. The battery must be replaced in them as it will leak and etch away gold plated traces on a board as well as migrate further down and eat a expensive connector. They are very stable freq wise. Big & heavy, but they do receive very well. I traded mine for a TS-930 and built a linear transverter which runs 2kc thru 510kc.

    You could build a nice transverter for your HF rig and get the same results plus the ability to transmit down low.

    Mike
     
  4. KD0CAC

    KD0CAC Ham Member QRZ Page

    WE0H ,
    Thanks John
     
  5. K6OQK

    K6OQK Ham Member QRZ Page

    HP-3586 B & C as receivers

    I'm sorry to be commenting on this so late, but I just ran across your question.

    Both of these make excellent VLF receivers, although I prefer the B version as I feel it's a bit more user freindly. They cover from almost D.C. to 32 MHz and are single-sideband receivers only, giving a choice of either upper or lower sideband (they do make a great CW receiver also). They take getting used to and you need to be aware that the AGC is in 5dB steps. This is because they are Auto-Ranging Voltmeters and not designed to be used a normal listening type receiver. However, you can lock the auto-range function so that it is not as bothersome, such as when listening to an AM Broadcast station where the sideband power is all over the place, So, in addition to using mine as a piece of test equipment, I do spend time using it to just listen around.

    I see them on eBay for anywhere between $50 to $1500. I'm sorry I don't remember the option numbers, but if having the Hi-Stability option and Jitter Measurement options is nice, but not necessary. You can drive them with an external 10 MHz reference for higher stability, which is what I do. The ones much above $450 seem to sit there for a long time - sometimes for years. I paid $300 for my first one and $75 for my second one, both off eBay and both in good condition. But like all eBay test equipment purchases you need to have some idea of what you see in the way of pictures and what the seller is saying, or is not saying.

    Bottom line: They are excellent receivers. They are the Rolls Royce of the Selective Level Meters.

    Burt, K6OQK



     
  6. G7HNY

    G7HNY Ham Member QRZ Page

    Earth signalling

     
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