New fuse for Astron 35?

Discussion in 'General Technical Questions and Answers' started by KM6LYW, Dec 21, 2018.

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  1. KM6LYW

    KM6LYW Ham Member QRZ Page

    Does anyone know how to procure a "3 AG 8amp" fuse?

    I googled it a bit, and there's no consensus on what "3 AG" means, slow blow?

    I've got a spare 10amp fuse in there, now, but, obviously can't leave it unattended that way.

    fwiw, fuse was blown while I was installing a new switch -- previous owner had circumvented it in an unusual manner.

    thanks for any hints,
    -craig
     
  2. AA5CT

    AA5CT Ham Member QRZ Page

    From a quick Google search:

    The 3AG, cartridge, fuses are miniature electronic fuses having a diameter of 1/4 inch and a length of 1-1/4 inches and are very common in North America. The AG designation stands for "automotive, glass" and reflects its original design as an automotive fuse back in the 1930's.

    AND - more discussion about than you would ever care to read in this lifetime:
    https://electronics.stackexchange.com/questions/61297/what-does-3ag-mean-in-fuse-block-3ag
    .
     
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  3. K1LKP

    K1LKP Premium Subscriber QRZ Page

    HI CRAIG,

    THIS PLACE WILL PROBABLY HAVE WHAT
    YOU NEED REGARDING FUSES
    you do it electronnics.jpg
    http://www.youdoitelectronics.com/

    IN THEIR SEARCH WINDOW ALL I DID WAS TYPE IN
    3AG AND YOU ARE LOOKING AT THE RESULTS ABOVE.

    I HAVE NEVER ORDERED ANYTHING ON LINE.
    THEY ARE CLOSE ENOUGH TO MY QTH THAT
    I JUST DRIVE DOWN TO THEIR LOCATION
    AND MAKE PURCHASES.

    ALSO CHECK OUT THIS SITE

    https://www.ebay.com/b/Littelfuse-Industrial-Fuses/181831/bn_7565495



    BIG BIRD WAVE.gif

    N9HI_Have_a_Nice_Day.gif 73 K1LKP.jpg

     
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  4. KM6LYW

    KM6LYW Ham Member QRZ Page

    Automotive Glass -- thanks! The size chart really helps as well.

    I found a "3AG 8A" fuse on amazon, but it's rated at 32V (automotive obviously).

    So I'm trying to procure a "3AG 8amp fuse 115V"

    The only 30mm fuses I can find are rated at "250V" (including the burned one I pulled out of the supply). 115, 250? does the voltage have an impact? Do the blow on the wattage or actual current?
     
    Last edited: Dec 21, 2018
  5. WC5P

    WC5P Premium Subscriber QRZ Page

    The original fuse probably has a 250 volt AC rating. You won’t find that at an auto parts store. Best bet is to order it from an online vendor.

    Sometimes I miss having a Radio Shack store nearby.
     
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  6. KM6LYW

    KM6LYW Ham Member QRZ Page

    NL7W likes this.
  7. KM6LYW

    KM6LYW Ham Member QRZ Page

    K1KLP -- love your post - thank you! looks like a SSTV image :)
     
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  8. WB8NQW

    WB8NQW Ham Member QRZ Page

    As far as I know the current rating of a fuse is independent of voltage. 8 Amps is 8 Amps. The voltage rating applies to the housing containing the fuse element. I don't think you will find a glass fuse above 250V. When the fuse blows the container must safely contain the arc and the gas produced. As the voltage rating rises the envelope is fiber or ceramic and usually the physical size increases to eliminate internal arc after the fuse fails.

    Bob
     
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  9. WA9SVD

    WA9SVD Ham Member QRZ Page


    Most 3AG fuses (very common) are rated at 32 Volts (as said, for automotive use or similar) or 250 Volts; I don't know of any "125 Volt" fuses. A 250 Volt fuse CAN be used in place of a 32 Volt fuse, or the non-existent 125 Volt device. Power supplies use the 250 Volt fuse, because a 125 Volt device is FAR too close to normal line voltage variations, and a 32 Volt device is obviously not appropriate. You may try your local auto supply store, but check the voltage before you buy. an 8A/250 Volt fuse shouldn't be hard to find; if you have a Fry's close by, they should have it.

    Never, EVER use a fuse with a greater current rating than the original! (I.E., in your case, over 8 Amps.) There is a REASON the supply manufacturer specified an 8Amp fuse; don't try to outguess the designers. Doing so is asking for a burned out supply, or even a fire! You should try to determine WHY the original fuse blew in the first place, in case there is some internal problem that caused the fuse to blow.

    P.S. Fuses are meant to prevent a fire in case of a malfunction. They MAY (or may not) actually protect the equipment attached to the supply.
     
    KM6LYW likes this.
  10. K6JEA

    K6JEA XML Subscriber QRZ Page

    Or, you could call Astron.

    949-458-7277

    I got a replacement switch from them a few years ago.
     
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