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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 couldn't find low ESR caps, so I ordered ones that had 1.33 ohms. Probably poor but it will still work. Can't find any of the Dual 50s like Walt has, so I ordered a 100uf/500V set. Hope it will work.
     
  2. AF6LJ

    AF6LJ Ham Member QRZ Page

    That should be fine and for the current demand you should be okay.
    The ones I ut in Oscar were low ESR and somewhat pricy.

    http://www.mouser.com/ds/2/427/159pulsi-35821.pdf
    Really good caps...
    I picked up eight 390MF at 450V
    They are low ESR and not cheap at nearly $17.00 each.
     
  3. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    Last edited: May 23, 2013
  4. KE3WD

    KE3WD Ham Member QRZ Page

    Be careful about looking at this as a "one input" problem.

    While the ESR is one of the parameters we look for, that parameter is likely to be of more value if the capacitor is going to be pressed into service in a switching power supply.

    But your use will not be hammering these capacitors like a switcher does. Not hardly.

    The aluminum electrolytic, as listed in the link, I look for the Temperature Rating. Higher is better.

    This capacitor has a 105 deg C Temp Rating and that is very good.

    Should work fine for a long time in this circuit.


    73
     
  5. AF6LJ

    AF6LJ Ham Member QRZ Page

    The ripple current rating will give you a clue as to the ESR
    Those caps you ordered have .65A ripple current rating.
    From what I have seen that is not bad.
    They should outlast you. :)

    What are you going to mount them on?
     
  6. AF6LJ

    AF6LJ Ham Member QRZ Page

    Good points, the only reason to keep an eye on the ESR of any cap used in power supply service is in relation to internal heating, which will shorten the life of the cap. In voltage doubler applications high peak currents can be an issue.
    When I selected the caps for my SB-220 (Oscar) that was my concern. I wanted caps that had both low ESR and a high operating temp. They will never see that temp, even if I ran the amplifier in an RTTY contest, all the better since my intent was to replace them once in the life of the amplifier.
     
  7. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    My mounting will be good old Radio Shack Perfboard. I can score some standoffs like the others have in the pix. I made a PCB for the SB-230 PS and it was a very messy affair where I splashed Ferric Chloride on my shirt and ruined it. Then it turned out I made the traces wrong and had to do some Cutting and patching to repair the error! So PERFBOARD will work fine and I ordered more 100K 5W resistors for bleeders. 17 dollars each???!!!! Man, that is ALOT of money for caps!!!! I didn't pay that much for my SB-200!!!

    In other AMP news, Now that I have 2 new 572Bs, I will put those in my current SB-200 and take the existing ones out to try AGAIN with the 6M amp. I saw a 6M SB-200 at Dayton, so that conversion is common!
     
  8. N2EY

    N2EY Premium Subscriber QRZ Page

    It would be interesting to see some calculations here showing the real effects of different ESRs in this particular application. (Yes, I could, but I'd like to see some other points of view).
     
  9. AF6LJ

    AF6LJ Ham Member QRZ Page

    That should work fine and standoffs are cheap.
    I have made a few PC boards using artwork and a contact printer.
    It makes correcting those layout mistakes easy and developing them before etching can be done in a bathroom with the window blocked or even in a black bag.
    Cool! My money is on it working.

    Besides the obvious effects like internal heating and shortened life when used in voltage doubler circuits, what did you have in mind. This isn't much more complicated than Ohm's Law to get you in the ballpark in terms as what to expect.

    In terms of dynamic regulation in high voltage low current supplies (More than 500V less than 2A) ESR has a very minor effect on dynamic regulation. The only reason to go out of one's way for low ESR caps is to minimize internal heating.
     
  10. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    I would like to know that too. When U need EIGHT caps, at $17 each, that is $136! at $4 each that is a more comfortable $32! So what I need to know is why the low ESR caps are worth a HUNDRED DOLLARS more than the not quite as low ESR caps! And, what the difference will be seen from such. I have used regular (non-LOW ESR) caps in the rest of the power supplies and amps I have repaired and all seem to work great! My Drake L7 is worked HARD every day, even on HIGH POWER RTTY!
     
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