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Cobra 139 led light meter project 1 of 4

Discussion in 'Station & Mobile Pics' started by foxman362, Sep 21, 2018.

  1. foxman362

    foxman362 New Member

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    Cobra 139 led light meter project 1 of 4



     
    Shadetree Mechanic likes this.

  2. foxman362

    foxman362 New Member

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    Here's Cobra 139 led light meter finshed project.
     

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  3. foxman362

    foxman362 New Member

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    Cobra 139 led lights meter done project
     
  4. Robb

    Robb Yup

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    Several pople here do restore work on old radios too.

    I see you used a lot of tape. Have you tried using shrink tubing? When tape gets old, it can loose its stickum and may cause a short. Another thing that is often done to old radios on this forum, is changing out the old, dried out electrolytic caps so that the radio stays working. Really refreshes them.

    Anyway, best of luck on your restore job.
     
  5. loosecannon

    loosecannon Sr. Member

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    whoo boy that was a bit hard to watch.

    I don't mean any disrespect foxman, but i'm not sure why you decided to make a video of that. If it's to show others how to do this type of mod, then wouldn't you agree that this is not what you would hope to see inside your radio if you paid someone to do this?

    The video seemed to be about trying to make something work regardless of what had to be done to do so.

    you ordered the wrong LEDs and then proceeded to make an easy job hard by forcing them to "'work" in your application. the use of electrical tape inside a CB radio is a big no-no because it does not deal with temperature changes well at all.

    It's good that you are trying to learn how to fix your own radios and improve them, but if you are going to make a tutorial video, you should probably wait until you know the right ways of doing these types of things. scraping that wire with the xacto knife held on the top of the faceplate had me cringing!

    It's your radio, and you can do whatever the heck you want to it, but the right way to do it would have been to get some wide angle LEDs and fit them into the stock rubber holders. then use small gauge stranded wire soldered together and covered with correctly sized heat shrink tubing.

    here is a link to some great LEDs to use for meter lights:
    https://www.ebay.com/itm/20x-Bright...668865?hash=item21132d7c81:g:QzwAAOSw6WdXiWTn

    they come in red, blue, and white, work off of 12vdc, shine a nice wide even light, and are available from the USA for cheap.

    hope this helps in your future radio work.
    LC
     
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  6. sunbulls

    sunbulls Well-Known Member

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    The first time I did a LED blue light replacement was back when it became trendy, but I soon replaced them with bright white LED’s. I didn’t like them either, even when I dimed them down considerably. Both the blue and the bright white LED’s were simply too harsh on my eyes. More importantly, they made it difficult for me to see the meter needle and lettering. Many folks were also disappointed with the early LED household bulb replacements for good reason. In the beginning you only had a choice between bright white ones or those with a bluish tint. Both were harsh, not to mention they were expensive. As it turned out, at least for me, the old school incandescent bulbs were still the easiest on my eyes. Two things have now changed. They're no doubt an offshoot for others like myself that still wanted the old warm glow of a household incandescent bulb. We now have “soft white” LED’s, and wide angle “diffusion”. These newer LED’s with both attributes closely resemble an incandescent bulb light, but they have a little more yellow content. None the less they are very pleasing on the eyes. Diffused LED’s are great for radio meters. The standard ones are often too directional. This usually results in having a bright spot in the center of the meter leaving the outer edges too dim. The LED’s I use on my radios nowadays are all diffused. If they don’t come that way from the manufacture, I lightly sand them with my Dremel tool. The other issue is brightness control. In almost every instance the resistor that comes with a ready-made 12v LED makes them way too bright for a meter. I usually start experimenting by adding 1.5K ohms or more in series until get the desired amount of light. By comparison, I like replacing the old grain of wheat bulbs mainly because of their durability and minuscule current draw, and after considerable trial and error with my own radios, soft white diffused ones are the only thing I use now. I can look at them all day long without going cross-eyed into some hypnotic transcendental state. For me, it’s all about being able to read a meter effortlessly. As for cool looking colored lighting effects, I get enough of that at Christmas.
     
    Shadetree Mechanic and dave457 like this.

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