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Powering multiple devices on single power supply

Discussion in 'General Technical Questions and Answers' started by KN6KKW, Feb 4, 2021.

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  1. KN6KKW

    KN6KKW Ham Member QRZ Page

    I have a samlex sec-1235m and a yaesu 991a radio. I just purchased a tuner for HF and realized I have no way to power it. It looks like a power pole power block is the way most people are going. I don't have the money for that right now though.

    So, my question is can I connect the tuner to the same terminals on the samlex power supply that my radio is using? I was thinking of twisting them together and then putting them in the power supply. Is there any danger or will this work temporarily until I get a power distribution system.

    The tuner (LDG AT-100PRO II) uses .5 amps I believe.
  2. W2SGM

    W2SGM XML Subscriber QRZ Page

    Perfectly fine, as long as you've got a fuse inline to the tuner. If you don't, you can pick them up from an auto parts store and crimp them in. It's a good idea to fuse both sides.
  3. W4NNF

    W4NNF XML Subscriber QRZ Page

    This will work fine...but makes for a mess of cables. When you are able, go to powerpoles and a powerpole strip. :)
    KU3X and KN6KKW like this.
  4. KN6KKW

    KN6KKW Ham Member QRZ Page

    The dc cable that came with my tuner doesn't have a fuse on it. I guess I need to learn how to get the fuse on the power cable. I've never done it before. How do you determine which size fuse to use? The tuner manual says it uses 500mah

    Is it really bad/risky to try it without a fuse? I sort of want to try it just to make sure the tuner works but I don't want to fry the tuner.

    I know my radio came with two fuses on the dc cable but the tuner didn't for some reason.

    Thanks for all the help.
  5. WA9FZB

    WA9FZB XML Subscriber QRZ Page

    Most of the small accessories I've seen (tuners, audio filters, etc.) do not come with inline fuse holders because they originally were used with wall-wart power supplies. Those things are never fused. Doesn't mean that is smart, just cheap.

    You can probably buy an in-line fuse holder and 1-amp fuse (at 12 VDC) at your local auto parts store for a couple of dollars.

    You could also use a commercial or homebrew terminal strip to connect two devices to one power supply. Just run heavy wire to the term strip and connect the two devices to it. I don't know your experience level, so I won't insult you by trying to explain how to make and use a terminal strip. If you need help, just yell and we will describe it.
  6. W4NNF

    W4NNF XML Subscriber QRZ Page

    Is the tuner powered by the radio? Is so the fuse on the radio protects it. I wouldn't worry too much about "no fuse" on these things. As FZB says, they are generally powered by wall-warts, which you could do if you are concerned.
  7. K2CD

    K2CD Premium Subscriber QRZ Page

    Going the other direction here. You say the tuner uses .5 amp, I assume at 12 - 15 V DC. A good quality wall-wart of 1000mA should handle that load. You could possibly do that until you arrive at a more elegant and permanent solution. I have a whole drawer devoted to wall-warts just for this type of use.
    KN6KKW and KC3PLJ like this.
  8. N3PM

    N3PM Ham Member QRZ Page

    I've used these a lot. 3M makes them and they use blade style auto fuses.

    3m fh 2.jpg 3m fuseholder.jpg
    Mike N3PM
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    "I have four 120V AC outlets in my room. Can I plug a lamp into one, a fan into another one, and a TV set into another one?":p

    The power supply doesn't know what's connected to it.:)

    Although regarding the AC line thing, my mother used to think that if you unscrew a light bulb from a lamp, electricity would run out all over the floor or something.:eek:
    2E0CIT likes this.
  10. WA9FZB

    WA9FZB XML Subscriber QRZ Page

    That could work, as long as the wall-wart is not a source of RFI. . .

    As NNF brought up, though, does the rig have a connector on the back to power an external tuner from the rig's 12 VDC supply line? If so, just use that and piggy-back onto the rig's fuse. The tuner won't care, nor will the rig (or the power supply).

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