power supply for qrp rig

Discussion in 'QRP Corner' started by KD2RON, Apr 22, 2016.

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  1. W5BIB

    W5BIB Premium Subscriber QRZ Page

    Thanks for the info Richard. It's as I thought, but wasn't exactly sure. I'm waiting on delivery of a NOS HWA-2036-3 supply for my HW-9 & picked-up this "wall-wart" @ our remaining Radio Shack for temporary use.
    BTW: Nice BIO/photos on your QRZ page. :)

    73 de Steve / W5BIB
    AA4OO likes this.
  2. AI6KX

    AI6KX Ham Member QRZ Page

    Changing the AC "polarity" has no effect on the DC output polarity.

    Wall-warts usually are fine for QRP rigs. Just get one that has about twice the current rating that what your 5-watter draws key down. 1-amp will work but 2-amps is safer.

    The 12-volt wall-warts all seem to have the correct DC plug and polarity these days but it can't hurt to check that the center pin is positive.
  3. W5BIB

    W5BIB Premium Subscriber QRZ Page

    I cut off the "plug" that it came with. Then checked (with VTVM) & found the "positive" side. I was worried about the "AC" polarity".
    BTW: I spent a very enjoyable 18 month tour (1965-67) off & on Okinawa @ Torii Station (Hanza) with the ASA 51st SOC & JSPC. :cool: I guess that's all changed now....
  4. AI6KX

    AI6KX Ham Member QRZ Page

    Not changed very much. The active duty folks and their families love their tours on Okinawa - a tropical vacation courtesy of Uncle Sugar. And the contractors are doing just fine thank you.
  5. K8JD

    K8JD Ham Member QRZ Page

    Wall Wart + GelCell
    I have a few gelcells , mostly around 6AH rated and not very big or heavy. I power them at a maintaining current rate from a mid size 12V wallwart that just has a simple halfwave diode rectifier and a filtrer capacitor. (I tore a few failed ones apart to find out)
    Those wallwarts are rated 12V 800-1000 mA. They have up t0 16 V open load so I use the GelCell to give me a more regulated solid 13V power. I use an automotive tail lamp between the wall wart and the battery, as a current regulator. This makes a fine field supply for QRP radio or auto radio bench supply.
  6. W5BIB

    W5BIB Premium Subscriber QRZ Page

    AA4OO - I heard you on 30m this afternoon but my 4 watts weren't enough!
    Nice fist Richard.
  7. W0RIO

    W0RIO Ham Member QRZ Page

    Beware of wall-wart ratings, most unregulated DC output wall warts are rated under load
    such as 12V/1Amp. At 0 amps, the voltage may raise to 18V or more and can fry your gear.

    Inexpensive switching power supplies can make a good QRP supply and can often be adjusted
    to an exact voltage such as the standard 13.8V. I've had good luck with MeanWell switching
    supplies. Switchers may produce a lot of RF noise, but the modern types are not too bad.

    Here is an analog power supply that I home-brewed, it's perfect for most 12V QRP rigs:
    KF5FEI likes this.
  8. KF5FEI

    KF5FEI Ham Member QRZ Page

    Ditto on the MeanWell supplies. You can score a 5-amp unit for pretty cheap on FleaBay. Just make sure you have a fuse on the power cable going from the power supply to the radio, just in case...
  9. KD2RON

    KD2RON Ham Member QRZ Page

    I was inflating my lawn tractor with my "Tire Slime" portable air compressor and realized it has a 12v output. Soldered the correct power plug and was in business. May be carrying a little extra weight but saved buying a battery and it has a nice handle and charger. Might also come in handy if I have a flat.
    W5BIB likes this.
  10. K8JD

    K8JD Ham Member QRZ Page

    This is Exactly why you need a current Regulator that actually limits the voltage into a storage battery. The battery sets a hard voltage limit as it is charging while you u use it to power your QRP rig.
    The discarded but working wall wart supply, light bulb siries regulator, and 6AH storage battery is a fairly inexpensive and lightweight setup to take into the campground or wilderness.

    Last edited: May 14, 2016

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