Need competent tech.

Discussion in 'Amplitude Modulation' started by N8WXT, Aug 10, 2019.

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  1. N8WXT

    N8WXT Premium Subscriber QRZ Page

    Mine are the same two for the lv caps but behind those where you have a large rectangular oil filled cap for the hv mine has two round ones . I have seen 32v1 transmitters with the rectangular hv cap in them so i dont know if that was a production change or if they were changed out ? . My manual does show the ones like i have in it so if i cant find a similar i might see about looking into changing it out for one similar to what you have in the hv section.
  2. N2DTS

    N2DTS Ham Member QRZ Page

    I think I changed mine to a 10 uf oil filled cap.
    I had some of those old round ones, but of course they are all very old...
    I may be able to give you an oil filled cap that fits...
  3. N8WXT

    N8WXT Premium Subscriber QRZ Page

    Ok as i said there are two of them but one seems to be ok its not leaking and i would be more than willing to pay you for the cap and shipping if you have one that would work.
  4. N8WXT

    N8WXT Premium Subscriber QRZ Page

    This is a pic of the placement of them on my 32v1 and of the one that leaked .

    Attached Files:

  5. WB2GCR

    WB2GCR Ham Member QRZ Page

    It's not mandatory that it be round, with a nut to mount on the bottom.
    These are not usually in production today.
    Someone may still have them, dunno.

    It is possible to open the can at the bottom, and replace the guts with a modern
    electrolytic (or sometimes film) cap. Epoxy it back together. This takes some
    appropriate tools.

    Alternately, you can also build up your own cap, using some aluminum or even
    PVC tubing, and a means to affix the cap to the chassis. Silicone rubber will hold
    the replacement cap inside the tube. A hole saw or flycutter will make the plug
    for the top and bottom from flat sheet using a drill press. Etc.

    Even a "twistloc", screw terminal, or PC mount cap could be employed using
    a short plastic or phenolic spacer/adapter arrangement.

    What's the value of the cap?

    The good part is that today's caps are typically much smaller for the same specs
    compared to the old...
  6. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    According to page 4-2 of the manual, there is 315 VDC coming out of the 5Z4 rectifier. Even with higher line voltages, the voltage should be well under 350 VDC. As such, modern 450 VDC capacitors should work fine. I would replace the 4 mfd 600 VDC capacitors with either 4.7 mfd 450 VDC capacitors or 6.8 mfd 450 VDC capacitors.

    Either one of the new capacitors are going to be very small in physical size and will easily fit under the chassis.

    I would definitely replace the 5Z4 and both 5R4 rectifiers with solid-state rectifiers. Remove the 5.0 VAC filament windings completely from the circuit. The Collins 32V- series, just like the Hallicrafters HT-32- series and HT-37, are VERY prone to the 5.0 VAC windings to short to other windings because of the presence of B+ on the winding. Going to solid-state rectifiers removes the high voltage from the 5.0 VAC windings because the low filament voltage is not required for operation.

    Glen, K9STH
  7. N2DTS

    N2DTS Ham Member QRZ Page

    Not sure I would use old caps, modern ones are much smaller and new...
    I have some though, never used....
    If you want them, let me know.
  8. N8WXT

    N8WXT Premium Subscriber QRZ Page

    I have decided on staying with a single cap I just ordered a new 8 uf 1000 volt from i have also ordered a new voltage rectifier tube as the one in it is not what is listed in the schematic . Thank you for the offer ill post updates here as I progress further into it im learning more and more as I do this but I want to do it so as to learn about the transmitter given my vary vary limited knowledge about electronics .
  9. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page


    An 8 mfd 1000 VDC electrolytic capacitor is probably going to be like 2-each 18 mfd 500 VDC capacitors in series inside a single tube.

    Glen, K9STH
  10. N2DTS

    N2DTS Ham Member QRZ Page

    Plasticap makes oil filled caps. I have some nice small ones that are a lot of capacitance and high voltage for their size.
    I think the original round ones were electrlytic caps, at least I always thought they were, early ones.

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