Datong VLF to 10m converterEarlier this year I obtained a vlf converter from Datong trough eBay. The total cost including shipping was about 12 euro. A real bargain. I saw the same converter a few weeks later again on eBay, this time it was won by a Frenchman for more than 60 euro. The Datong converter converts the vlf band to 28 MHz, so 28.000 MHz is actually 0.000 MHz. 28.136 MHz is the 136 kHz amateur band. And so on. You can also convert the medium wave bands too but at reduces sensitivity according to the manual. I attached a kind of loop antenna to the input wich hung in the bedroom (XYL not happy) and started listening to all kind of stations. I heard a NDB beacon from North-France and many others. DHO38 on 23,4 KHz was loud and clear. Many other stations were heard. The transmission of the VLF transmitter at Grimeton was planned fot july first. On a sunday. My XYL had to work so I took the kids and all my gear to my parents home. This time the videocamera was packed too. The antenne I made that day was a bit too large for the converter, the manual says that it has a lot of gain, a small whip antenna should be enough. The 14 by 2 meter loop produced strong broadcast signals everywhere. Found a potentiometer and wired it in the coax line to reduce the signal. Much better. The result of this setup can be heared and seen on this short video I made and posted on YouTube :

9 Responses to “CQ from SAQ VLF transmitter july 2007”

  1. James Hyslope says:

    Saw your video on youtube (first). Sent me on a QUEST for the “Datong” converter 🙂

  2. Joost says:

    Hi James,
    I have a schematic drawing of the converter, it uses an SO42P IC (obsolete I believe) if you like to build one yourself. But there are other converter designs one can build. You can order a new one at this site http://www.palomar-engineers.com/VLF/vlf.html (not cheap, but the Datongs I found after my auction on Ebay weren’t too).

    On the other hand, you can always receive up to 22/24 kHz using your sound card and a piece of wire. For example http://freenet-homepage.de/dl4yhf/spectra1.html or http://www.visualizationsoftware.com/gram/gramdl.html.
    See also http://www.vlf.it for more on VLF

    Enjoy, Joost

  3. James Hyslope says:

    Just won the Bid at eBay for the Datong VLF. Cost me with shipping USD $84.45 and seller requires money order only. So is going to take awhile for me to receive 🙂

  4. Joost says:

    Congrats, I had more luck back then, total cost was about $10 ~ 12. Don’t oversize the antenna 🙂
    I believe that I have a manual somewhere on my HD, if you need it, I’ll mail it to you (can be found at http://www.mods.dk)

    Joost

  5. F6eju jean claude says:

    hello to all radio friends.

    I have an issue with my qth surrounded by the montagnes.
    The signal of SAQ are very weak even with a long wire of 25 m.
    Vertical antenna for the Hf gives better results but SAQ on 17.2 Khz is still pratically impossible to hear or see.
    I have made a converter working fine on others signals VLF, drawing on my pictures Picassa web site
    I am seeking for the best loop for such reception, advice welcome.
    Thanks.
    Best 73
    F6eju
    http://picasaweb.google.fr/La.galene/RadioAmateurQRPPTunaTinF6EJU#

  6. Joost says:

    Bonjour Jean Claude,
    I have a Datong VLF converter but it seems that it has too much gain on the input, so big antennas are no good. But to be honest : the best results I achived was with the 24 turn loop in the summer. In the winter the signals seems much weaker to me….
    Maybe you could find more/better info on http://www.vlf.it
    On my Youtube movie all the other VLF signals are 9+20, but SAQ hardly moves the needle from the s-meter. The antenna was a 1 turn loop from 14 by 2 m. With a potentiometer in the antenna line to reduce overloading.

    Nice pictures on Picase 🙂
    73 Joost

  7. Jean Claude says:

    Thanks Joost for your reply that I found today ” 17 of January 2009″ Hi
    Have made some little progress . 🙂
    Will be happy to exchange ideas
    Best 73
    f6eju
    jean claude la.galene”at”gmail.com

  8. Joost says:

    Hi Jean Claude,
    I usualy post the replies on the comments here to benefit everyone.
    Have you ever tried it with an antenna in the input of your soundcard ?
    I have also built several years ago a BBB4 vlf receiver. You can barely call it a receiver 🙂 It is some kind of active probe with a fet amp. Look in Google for Steve McGreevy.

    Joost (who is now attacked by my youngest daughter, she wants to type someyhing on the keyboard)

  9. jean claude F6eju says:

    Hi Joost

    I am comming again Hi.

    In fact I have made an pre amplifier and got better signals.
    You will find some pictures at:
    http://picasaweb.google.fr/La.galene/HamRadioF6EJU#

    Next time I hope to read SAQ in better condition.

    Yes I have proved to connect the ant to the sound card with spectrumlab, but the best result with a vertical HF antenna is obtained with the op27 pre Amp.

    Will do a loop with biggest wire diameter possible and abt 70 turns as Renato advice me , see vlf.it

    We keep in touch.

    Best 73’s from the French riviera in jn33rv

    Jean Claude de f6eju