Power Supplies

Discussion in 'Amateur Radio Equipment Reviews' started by W1GVT, Oct 6, 2013.

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  1. AA4HA

    AA4HA Ham Member QRZ Page

    For 90% of what I do a linear supply is perfect. There are really only two advantages I see to a switcher;

    1) weight
    2) a slight advantage of efficiency under certain types of loads

    A linear supply has the advantages of;

    1) no RFI from DC/DC converters, oscillators, etc...
    2) repairable
  2. KB1NXE

    KB1NXE Ham Member QRZ Page

    I have two Pyramid power supplies. An adjustable and a fixed. Both are very stable linear supplies. Not expensive either. Sold by R&L (and others).
  3. BH3MDE

    BH3MDE Ham Member QRZ Page

    The linear supply good to HF radio low wave disturb output
  4. KF7VXA

    KF7VXA Ham Member QRZ Page

    I have a switcher that works great and an Astron that some idiot threw in the trash pile at the dump. It was bent and had been rained on, not to mention mud on it.
    I took it home, cleaned it up, replaced the broken fuse holder, straightened the cabinet, replaced the feed wires and it works like a champ.
    The one really good thing about the Astrons is that if there is a problem, they are very easy to fix. As was mentioned, a switcher, if it goes south, it's trash time. Not a bad idea to make a crow bar to go between a switcher and your equipment no matter what the manufacturer says.
    The switcher is an EBay special, 36 amps. It has held up great and is quiet. I bought it mostly for a smaller higher amperage supply for an EMCOMM box. I have added a crowbar. It's fan is pretty quiet and no decernable noise in the radio, but if it goes bad, it gets trashed. The Astron will get passed down to my son and most likely his too. I give the switcher another 2 years or so. I'm sure there are some darn good one's out there though.

    73's John KF7VXA.
  5. M0GVZ

    M0GVZ Ham Member QRZ Page

    MyDel MP-30SW3 which is sat right next to my TS590 and I used that in this last weekend's CQ-WW contest. I also have a SPS9400 40A.

    Your 20A one if its 20A constant plus a little for surge should be absolutely fine on SSB.
  6. M0GVZ

    M0GVZ Ham Member QRZ Page

    On SPS's the voltage regulation is a closed loop and if the IC doesn't receive the voltage it expects it shuts the whole thing down. There is no relying on feedback to shut the oscillator down - or at least on a decently designed one there isn't. The only thing that should happen in a SPS in a fail event is zero output unlike a linear which usually puts the full output of the transformer secondary less voltage drop over the rectifier.
  7. M0GVZ

    M0GVZ Ham Member QRZ Page

    My Manson EP925 Linear PSU had an horrifically loud fan. My SPS9400 switch mode has a loud fan. My Mydel switchmode is almost silent. If it has a loud fan it is because the manufacturer has put in a loud fan, not because its a linear or a switch mode. And for £10 you can swap the loud fan to a quiet one with as much if not higher cfm.

    I'd say that is more because of your lack of technical ability than the cost of repair. Any moron can diagnose a faulty linear - just keep going from the transformer until the voltage stops. A switch mode takes a little bit of actual knowledge. Usually all that fails is a cheap component in the feedback circuit or the IC itself which are pennies, actually cheaper than the few bucks you pay for the regulator in a linear.

    And yes I've seen the waveform coming from them on a scope and the waveform coming from linear PSUs as well. The only difference between the two is that the noise on the switch mode will be higher frequency but linears can and do have AC ripple.
  8. KY3W

    KY3W Ham Member QRZ Page

    Ah, yes. British arrogance at it's finest.

    I've repaired many PC PSU's over the years and I can assure you, they're not worth fixing. Most cases were around $25 in parts and an hours time. A new 550w PSU is around $50. I can say the same for Amateur PSU's. Often having spent as much as $50 in parts to have it fail again a few months later. I can't speak for anyone else but I'm not the kind of guy who would buy a new SPS then turn around and buy a good whisper fan for it. It should already have one.

    I only buy Astrons but I can tell you that when the VR fails, it often throws 19V to the rig. However, it's very low current and I've never seen or heard of that damaging a transceiver yet. And alas, no fan needed. Some of them do buzz a bit but I kinda like that.
  9. KG4NEL

    KG4NEL Ham Member QRZ Page

    Harkens back to an earlier day in radio :D
  10. M3KXZ

    M3KXZ Ham Member QRZ Page

    Racist :)

    I ditched the SMPS in my PC when it failed, and replaced it with one being given away free. If i was a moron then I would have spent time repairing the broken one. But my radio SMPS cost a lot more so that I would definitely repair rather than ditch.
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