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hallicrafters SR-2000 time delay relay?

Discussion in '"Boat Anchor" & Classic Equipment' started by WA6MHZ, May 20, 2013.

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  1. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    I am going to recap the PS, but on K9AXNs site, he recommends 90uF caps and not the usual 200uF that I replace stock caps with. So will have to look for those. His website shows a nice pic of a recapped PS
    http://k9axn.com/_mgxroot/page_10801.html
    he has the caps up on Plexiglass panels on spacers above the chassis.
     
  2. W4OP

    W4OP Ham Member QRZ Page

    Join the Hallicrafters Yahoo group. The most knowledgeable hams on the 2000 inhabit that group.

    Dale w4OP
     
  3. WD0GOF

    WD0GOF Ham Member QRZ Page

    Here is my recapped PS-2000. I etched pc-boards for the caps. Nylon standoff's from ACE hardware. I used dual 50uf caps, paralleled each section to get 100uf in order to reduce the ESR. Ended up with ripple measurements 1/2 normal.

    P1010018.JPG

    73, Walt.
     
    Last edited: May 22, 2013
  4. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    What size caps did you use, Walt? (uf value and Voltage)
     
  5. AF6LJ

    AF6LJ Ham Member QRZ Page

    The picture shows dual fifty microfarad caps at five hundred volts.
     
  6. N2EY

    N2EY Premium Subscriber QRZ Page

    In the picture they are labeled 50/50 uF, 500 volts. That gives 100 uF, very close to the recommended 90 uF.

    Nice job, Walt!
     
  7. WD0GOF

    WD0GOF Ham Member QRZ Page

    Actually the original design for those caps is 90uf/500vdc, double check your manual. Eight 90's in series for 11.25uf. Eight 100 in series yeilds 12.5uf so not much difference. The MOST important thing is the ESR rating. Some inexpensive readily available caps have ESR's of greater than 2 to 3 ohms. A good cap for this application will have less than 0.5 ohms. The caps I used are rated at 0.08ohms.
     
  8. AF6LJ

    AF6LJ Ham Member QRZ Page

    That is a good job,
    By the way Pat, if you should want to copy one of the rebuild jobs shown in a link presented earlier in the thread I have some plexiglass sheeting of the same thickness used in that one power supply rebuild, you are welcome to it.
     
  9. KE3WD

    KE3WD Ham Member QRZ Page

    The typical tolerance of electrolytics is so wide that a 90uF or two 50uF in parallel are both likely to be above the 100uF mark in actual practice.
     
  10. N2EY

    N2EY Premium Subscriber QRZ Page

    Good points all.

    Some folks might benefit from an explanation of why low ESR is so important in that application.
     
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