Linear Or Switching Power Supply?

Discussion in 'General Technical Questions and Answers' started by KT4JX, Mar 29, 2008.

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  1. NA0AA

    NA0AA Ham Member QRZ Page

    I have three Astrons, RS-7, RM-50 regulated linear supplies, one SS-25 switcher and two Pyramid 3 amp regulated. Plus the bolt-on switcher accessory PS for the Yaesu FT-897.

    All of 'em work just fine for the jobs they do. The Astron switcher has a fan which I find annoying, none of the linears require them.

    Unless you have to schelp it around, I see no reason to go with the added complexity of a switcher.

    My two cents.
  2. N6YG

    N6YG Ham Member QRZ Page

    I was using a early Jetstream switching power supply for a while. It had major issues with birdys and RFI. It was really easy to compare it to my Astron 70 amp supply. I just tuned up and down the bands and took notes. then switched the power supply and did it again. The Switcher was definitely producing lots of noise. It probably wouldn't be an issue because the only time you would notice it, is if you just happened to be on the same frequency as the RFI. I wish I had saved those notes, If I recall quite a bit of the noise was outside the ham bands but there was enough inside the bands to make me ship it back.

    I'm sure they have improved since then. All they needed to do was move most of the RFI off the ham bands.
  3. KC9ECI

    KC9ECI XML Subscriber QRZ Page

  4. W8ATA

    W8ATA Ham Member QRZ Page

    I have two linear supplies, both Astron. One is the 50 for powering two HF trancievers (one at a time) and the 35 for the small VHF/UHF shack rigs. I have had no problems with either and they have some years on them. Rarely do you hear any negatives about them. They are keepers.

    My new amp I am now shopping for will have a switcher supply. In my opinion the major switcher power supply manufactures are for the most part designing clean supplies. They have come to realize we won't buy the hashy ones. And we get what we pay for.

    My best to you.
  5. PA5COR

    PA5COR Ham Member QRZ Page

    I have 2 Sec 1223 PSU's switched mode, both clean and used on hollidays.

    I always build my own PSU's L200 as regulator, first one 80 amp still used on the workbench after 23 years hard use
    Second one 15 years 40 amp, also on the workbench, used hard.

    Feeding my FT 847 and FT 100 is the homebrew 40 amp 45 peak PSU linear L200 voltage and max amp regulated.

    I use overkill transformers, rectifying bridges, for the 40 amp .5 Farad buffer condensator, slow start, input mains filter, output filter, check with scope the output with different loads for any sign of oscillation or noise.
    Transistors used are 2N3772 8 of them on an heatsink with 5" temperature controled fan.
    On that heatsink the rectifying diodes are mounted as well, automotive 150 amp each.
    Crowbar overvoltage protection.

    Then it gets an 24 hour run of full output into an load, and has to survive that.
    Followed by an 24 hour short circuit test.

    If that all passed succesfully, it is taken into service.

    Maybe i waste some power, but i had never one PSU failed on me i build myself.
    When you have an small fortune of transcievers beeing fed with an PSU, i don't want it to fail.

    Just my 2 p
    Last edited: Mar 29, 2008
  6. N8UZE

    N8UZE Ham Member QRZ Page

    I have an MFJ switching power supply and it's great. There's no noise and it's light as a feather. I take it out to Field Day, on trips, and have even loaned it to friends when they go on trips. If you get a good switching power supply, designed for amateur radio use, there should be no problem.

    I also have linear power supplies (got them with the radios in each case). They are, of course, quiet by nature. However they are HEAVY and thus very inconvenient for portable use.
    W1SRR likes this.
  7. W4HAY

    W4HAY Ham Member QRZ Page

    I've used Astron linear supplies for years without any problems. If I was going to be carrying one around a lot, I'd consider a good quality switcher -- unless it was for small-signal work.
  8. W4INF

    W4INF Ham Member QRZ Page

    My Jetstream JTSP28 has worked well under hard demands and I have no complaints.

  9. N5USR

    N5USR Ham Member QRZ Page

    I'm partial to linear supplies since they (usually) have no moving parts and are very quiet. I have a couple of Astrons (35 and 20 amp versions) that I bought used and they still run great 24x7 15 years later.

    But I did recently buy a Jetstream switcher, the light weight sure is nice for some applications. And it does its job just fine without any RF noise issues. The cooling fan, though, drives me crazy! It cycles on and off with temperature, and is almost the loudest cooling fan I've ever heard (second only to the fan Dell put in my Power Edge server). At some point I'll do surgery and replace it with something quieter, but wow...

    The Jetstream has for now been relegated to my repeater setup in the back room where I don't have to listen to it!
  10. K8JD

    K8JD Ham Member QRZ Page

    The only application I would consider switching PS is 2M grab $ go setup where I will be on FM and listening to local, strong signals. Weight and convenience art the only plus for that .
    The home station where the PS is buried under the desk and weak signal work is the norm, required a noise free device.
    There are some high end switchers that actually have adiquate filtering, but these are rare and expensive.
    I have several Astron supplies, RS 7 for running VHf mobile rigs in ;the house and the RS
    35 and 40 for HF rigs.

    7 go portable setup
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