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Thread: George, Eddie, Warren, Jerry, Pat ('MHz) et al - inductor question

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    Administrator N8YX's Avatar
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    George, Eddie, Warren, Jerry, Pat ('MHz) et al - inductor question

    Can any folks who may have been involved with the electronics industry during the '70s help me out with a part?

    Below are pictures of a molded choke. It's a 10uH value but I'm not sure of its current rating.

    Which manufacturer made these things, and what case type is it?

    Bonus Points: If you have a few in various values kicking around your junk box I'll gladly buy them from you.

    IMG_20140302_120401_958.jpg

    IMG_20140302_120342_297.jpg
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    Conch Master KJ3N's Avatar
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    What did it come out of?
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    La Rata Del Desierto K7SGJ's Avatar
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    Those were quite common in TVs of that era. As I recall, they were often used as peaking coils in Chroma and IF circuits as well as sound IF. They were often made by Miller and Millen. I looked in a 1960 Miller catalog I have, but could not find that configuration. I don't have a clue as to max I through them. If you have a bad one, I suppose you could crack it open to see what size the wire is. What did it come out of, and what circuit was it in?
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    Administrator N8YX's Avatar
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    Quote Originally Posted by KJ3N
    What did it come out of?
    Quote Originally Posted by K7SGJ View Post
    Those were quite common in TVs of that era. As I recall, they were often used as peaking coils in Chroma and IF circuits as well as sound IF. They were often made by Miller and Millen. I looked in a 1960 Miller catalog I have, but could not find that configuration. I don't have a clue as to max I through them. If you have a bad one, I suppose you could crack it open to see what size the wire is. What did it come out of, and what circuit was it in?
    One of the Stoner exciter boards currently on the bench; circa 1978. See the ongoing restoration saga over in the CB section of the site. If one takes a look at the circuit in question, there's no apparent way this thing could source enough power to cook itself unless a collector to base short is occurring (which it isn't) -or- the transistor is oscillating instead of amplifying.

    I have a collection of these parts upstairs, sourced from many old Radio Shack "Coil and Inductor Assortments" (remember those?). Of course, I don't have a 10uH...
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    La Rata Del Desierto K7SGJ's Avatar
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    I am assuming it is in the collector circuit source supply. What device number is it feeding? You can check specs for the device and get an idea of max I.

    Never mind, I just read the other thread post.
    Last edited by K7SGJ; 03-02-2014 at 01:22 PM.
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    Administrator N8YX's Avatar
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    Take a look at bottom center of the JPG in the link:

    http://www.sofafunker.de/stoner/stoner_analog_2.jpg

    The inductor in question is L514.

    I found some 10uH parts in my junque-box upstairs but they're about 2/3 the size of the original - even though the coil itself appears to be would on a form of the same size.

    From the looks of things, I'm the first one to get into the PA area of the rig - it's all original.
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    La Rata Del Desierto K7SGJ's Avatar
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    Quote Originally Posted by N8YX View Post
    Take a look at bottom center of the JPG in the link:

    http://www.sofafunker.de/stoner/stoner_analog_2.jpg

    The inductor in question is L514.

    I found some 10uH parts in my junque-box upstairs but they're about 2/3 the size of the original - even though the coil itself appears to be would on a form of the same size.

    From the looks of things, I'm the first one to get into the PA area of the rig - it's all original.
    E-B short is about all I can see, that would cause that, too. Since that didn't happen, about the only other condition would be if the driver were driven into saturation or was biased full tilt. I can see where the choke would open before the device would be damaged. If you can't find a suitable replacement, you could wind one on a 47 ohm 1/2 or 1 watt resistor as a form, and remove the 47 ohm resistor that the choke parallels on the board; at least until you can find another 10uh of that configuration for original aesthetics.
    Last edited by K7SGJ; 03-02-2014 at 01:45 PM.
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    Conch Master KJ3N's Avatar
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    Given the maximum collector current of the MRF-476 is 1A, I would think that one of the following would suffice.

    http://www.mouser.com/ProductDetail/...aWsPXPTjmfQ%3d <- rated for .5A

    http://www.mouser.com/ProductDetail/...2CTE%252bUU%3d <- rated for 1A
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    I'm thinking you may be right, Jim.

    After I get done with a few other radio related activities I'm going to revisit this thing...with a scope and a couple more pieces of test equipment. Last night, the problem still manifested itself if the PLL/Counter Board was unplugged from the chassis. All RF and IF signals are generated on that particular board, so something is causing the device in question to behave weirdly. I need to see if an oscillation is present.
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    I can't see well here on the phone want it is. Probably those 3 hole ferrite sleeves but I can't tell. I am guessing that Q is more important than inductance values. I started in the business in 1980.

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