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What is this thing?

Discussion in 'General Technical Questions and Answers' started by KI6ZON, Apr 7, 2012.

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  1. KI6ZON

    KI6ZON Ham Member

    I got this piece of equipment from a pile of free junk that was brought to a meeting of my local radio club. I have no idea what it is, though, it just looked like an interesting shack decoration. As the unit on the meter is micro amperes, I thought it might be some kind of field strength meter, but it doesn't budge even with RF power right next to it. It has no mark of any company on it except the meter, which reads MICRONTA. Any help identifying it would be appreciated.

    Here's the pictures: https://picasaweb.google.com/SutterLaird/MysteryDevice?authuser=0&feat=directlink
     
  2. WB2WIK

    WB2WIK Premium Subscriber

    I have one just like that, if you want to have two of them.

    Just kidding.

    Definitely homebrew. Looks like a critically tuned circuit, and if it's a DC microammeter may well be a field strength indicator of some sort although I didn't see a detector diode in there (might be one, just not easy to see). If it is, it may be critically tuned to some frequency you haven't tried and that's why it doesn't indicate anything.

    For example, if it's tuned to 13.68 MHz or something, unless you transmit there the meter may not indicate anything.
     
  3. KD8DEY

    KD8DEY Subscriber

    It's a home brew field strength meter (Uncompleted- tunable) used to foxhunt 11m operators.
    Those 2 holes in the front were intended for use to hook up a surplus WW1 Headset. :)
     
  4. WB2WIK

    WB2WIK Premium Subscriber

    Sounds reasonable. Probably accurate.

    How the heck did you know?:eek:

    If it's for CB and it does appear to be critically tuned, the meter wouldn't indicate anything unless you transmit near it on 27 MHz. Might respond to 28 MHz also, but probably not other bands.
     
  5. KI6ZON

    KI6ZON Ham Member

    Thanks! You got it! I keyed up my CB radio next to it and the meter moved (see photo). What was the headset used for?
    IMG_0649.JPG
     

    Attached Files:

  6. KD8DEY

    KD8DEY Subscriber

    High impedance magnetic headset to help keep from loading down the circuit while allowing you to listen in on the signal being "hunted"
    am I mistaken or is that a 1n914/4148 below the ceramic capacitor??
    the 2 holes looks like somebody knocked out the banana jacks.
     
    Last edited: Apr 7, 2012
  7. KK4AMP

    KK4AMP Ham Member

    Bubba, it's certainly a diode of some kind. OP, if you loook up a crystal radio circuit, you'll see some similarities between it and what you've got there. :)

    Guess the pot is there to keep the meter from pegging. :)

    So yeah... homebrew FSM. Micronta is just the brand name of the meter movement, which came from good old Radio Shack.
     
  8. KT7DAD

    KT7DAD Ham Member


    ??????????????


    Do you have little porslain figurines also?
     
  9. KI6ZON

    KI6ZON Ham Member

    I can clarify that. This was on a pile of junk that was going to be disposed of, and even if I couldn't figure out what it was, I thought it was cool and might look interesting with the radios.

    Could I put them back, and if so, how? I don't know if I have any use for it, but I've become rather fond of it.
     
  10. KD8DEY

    KD8DEY Subscriber

    Or you could just fill them with JB Weld, sand and paint.
     
  11. K9STH

    K9STH Ham Member

    There is probably a diode across the meter movement which cannot be seen in the photo. With the coil and variable capacitor it looks like it should work on at least 20-meters through 10-meters, maybe as high as 6-meters and as low as 40-meters.

    Just a simple field strength meter.

    Glen, K9STH
     
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