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Restoration of the R-390A

Discussion in '"Boat Anchor" & Classic Equipment' started by SV2SBE, Nov 28, 2019.

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  1. K6BSU

    K6BSU Ham Member QRZ Page

    Now, I'm worried! I thought those "bathtub" capacitors were sealed and would last forever. There are some in my SP600 that I didn't change when I changed all the other paper caps. Well, the radio works fine, so I'm wondering if I should bother with the bathtub caps?

    (not exactly worried, but only "concerned".)
     
  2. SV2SBE

    SV2SBE Ham Member QRZ Page

    last check before the "smoke test" and the start of alligment procedure

    78793945_10217785555302131_1072625823992774656_n.jpg
     
  3. SV2SBE

    SV2SBE Ham Member QRZ Page

    i dont know if they will last forever, but mine was 60 years old. The line filter that was selaed too, was drop my main house fuse 3 times, until i remove it and check the receiver without the filter.
    So, anything in that age range will fault sooner or later. You choose the depth of the restoration.
     
  4. SV2SBE

    SV2SBE Ham Member QRZ Page

    After an hour listening and preparing to start the alignment, suddenly the house main fuse dropped, rsset it and dropped again. Searched for the fault in the 390 and the fuse of the radio was ok. So i desoldered the line filter and tested alone, dropped the main fuse again.
    Now you know, a propane torch, heat and open it, it was a big mess with all that wax to clean, and you can see the components, 4 capacitors to change and 2 coils to clean.
    will tell the results soon.
    78994115_10217834068154922_1675449665379631104_n.jpg 79218679_10217834068754937_5885652101006098432_n.jpg 79507011_10217834069634959_1287721252215062528_n.jpg
     
  5. WB2GCR

    WB2GCR Ham Member QRZ Page

    Beeswax.
    Heat gun + metal or glass cooking pan.
    Removes all but a thin coating.
    Solvent will take the rest, need be.
    Save, heat, pour it back in.
    Likely the caps... :D
     
  6. SV2SBE

    SV2SBE Ham Member QRZ Page

    ready - tested -
    surgery succeed, patient alive!!
    79376246_10217837092870538_7232400239821324288_n.jpg
     
    W7ANM, KB2FCV and KA0HCP like this.
  7. W5UAA

    W5UAA Ham Member QRZ Page

    Cape Newenham? My father was there 1954 as an intercept radio operator for the Air Force also. Passed weather traffic, welfare and routine messages via CW. Also "dit ditted" the russians on the other side on Christmas and New year's eve. Maybe you new him? Maybe you remember him with a couple of stripes and spoke with a funny french accent? Same name as me, but no "Jr."
     
  8. W3TA

    W3TA Ham Member QRZ Page

    The caps in those line input filters are typically very leaky and when the radio is plugged into a GFCI outlet will easily trip it. On my 390's I typically remove that filter and replace it with a modern line filter - no more GFCI tripping! I make a blank off plate for the hole from some Delrin. Once the cover is installed, you never see it.

    IMG_3922.JPG IMG_3923.JPG IMG_3951.JPG
     
    WB2GCR likes this.
  9. W2VW

    W2VW Ham Member QRZ Page

    Is that leaky or just enough capacitance to allow enough current flow to trip a GFCI?
     
  10. WB2GCR

    WB2GCR Ham Member QRZ Page

    Hope you refilled it with the Beeswax??
     

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