My PS-23ish project

Discussion in 'Homebrew and Kit Projects' started by AC9QC, May 19, 2017.

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  1. AC9QC

    AC9QC Ham Member QRZ Page

    Well, where to start; I'm pretty deep into building my own PS-23 substitute power supply. Yeah, I have more into this than one off Ebay would have cost before rebuild, but what's the fun in that? I'm using a combination of new buys, junk box parts, hamfest parts and recycled other stuff. I have a 3K 225W resistor I intend on load testing this with, and that will likely get hooked in series with one or two of my 250 ohm 50W resistors I have for my dummy load.

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    This is the first section, it's for 300V. I dremeled the board up with an engraving bit. It's crude but it seems to work well and make nice, wide traces.

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    A PC PSU makes a great source of snap-in capacitors and a hunk of the PCB can be used as a template for drilling their holes too.

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    All snapped in. Never mind the holes in my log book made in haste!

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    Rest of the holes for this side. I ended up putting the doubler circuit on the other side.

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    The down side is that the solder seems to "flatten" considerably due to the surface area conducting heat the way it does.

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    Some salvaged PC PSU parts; I had to supplement these with a Digikey order.

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    300V and bias board ready to go.

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    Here's the HV board. It's extremely simple, much like the original Heathkit was. The center rectangles are where the diodes will go ultimately, and the 2 holes in the middle are for the AC.

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    The two nearly assembled boards ready to go.

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    Inside of the chassis. Since I measured the main power transformer at 360-0-360 and I need 720ish volts and 300ish volts I'm going to be a bit over after capacitance is added. Yikes! I added a few resistors accordingly. Main B+ will likely still be higher than the original PS-23, but I've read of other OEM units running higher on a pair of 6146es and it's still within the range Heath gave for the HW-101.


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    The boards are going to be mounted on top (protective plastic below to prevent shorting from the PSU I'm using as a chassis) and from left to right:

    7HY choke salvaged from a GE Mastr TX power supply
    5HY choke from Digikey, new Hammond
    50VCT transformer from something I took apart years ago and can't remember. Reel-to-reel maybe?
    Hamfest power transformer. 720VCT, 12V and unknown center tapped green winding.

    You can see the connector on the side of the chassis from this view, it's above the left PCB.
     
    KA9UCN, AF6LJ and KE4OH like this.
  2. AC9QC

    AC9QC Ham Member QRZ Page

    Took my 225W 3K resistor and did a little load testing. I got 780V for my HV and 330V for my MV. I think that will drop down some more to about 290V when I have it at the full 150mA, and the plates will see about 800V when I have full B+ applied. I'm thinking it's time to start hooking stuff up to connectors, I have an HW-12 that will probably get hooked up first provided I don't have to do a ton of work to make the cables.
     
    AF6LJ likes this.
  3. K9STH

    K9STH Ham Member Staff Member QRZ Page

    You need to drop the lower B+ at least 50-volts if you are going to use the power supply with an HW-12. Heath provided the 2-different lower B+ availability on the HP-23- seres (and the PS-23 which is the same as the HP-23C) so that the power supplies could be used with a much wider range of Heath equipment besides the HW-10X and SB-10X series. Even the SB-110 / SB-110A require the lower voltage not forgetting the mono-banders, the MT-1, MR-1, HX-20, and HR-20.

    Otherwise, if you use the power supply with the higher low B+, you are going to have problems and may even damage the HW-12.

    Glen, K9STH
     
    K3XR likes this.
  4. KX4OM

    KX4OM Ham Member QRZ Page

    I would put the PC boards on 1/2-" metal standoffs, and move the other discrete components to the underside of the PCB, soldering them directly to the copper. That is for safety, assuming that you are not going to build a cage on the top of the chassis. I have the same issue, as my HP-23B has a Mike Bryce (Sunlight Energy Systems) HP-23R board, which mounts on top of the chassis with a lot of high voltage components exposed. Mike has a warning on the web site about safety with regard to that. It is mounted in the Heathkit SB-line speaker enclosure that has an open back. Rather than enclosing the back of the speaker with perforated aluminum, I'm contemplating modifying the power supply back to stock, with the four 500 volt caps mounted on top similar to the Galaxy AC-400 power supply that I rebuilt. That unit had enough space for putting all the other components under the chassis. I didn't need to use standoffs for the PB board.

    Photos of the Galaxy unit are attached. The other aluminum cap is a 25V 2,000uF can that I cut and stuffed with a new cap.

    Ted, KX4OM

    HV-caps-1.jpg HV-caps-2.jpg
     
    Last edited: May 28, 2017
  5. AC9QC

    AC9QC Ham Member QRZ Page

    Actually it's funny you should mention that, I have a sheet of acrylic here I was giving contemplation to bending to cover it up yet keep it clear; It seems to be a pretty junky piece (it cracked when I drilled it) so instead I'm giving contemplation to building some form of cane metal cage for it.
     
  6. KX4OM

    KX4OM Ham Member QRZ Page

    Another thing to consider for the cover is the aluminum tops of the HV caps. Following the Heathkit design, the ones in series in the voltage doubler circuit will have HV on the aluminum top of the cans.

    Ted, KX4OM
     
  7. AC9QC

    AC9QC Ham Member QRZ Page

    Yeah, my game plan I think is going to be to bend a piece of sheet acrylic so that it covers up the whole capacitor assembly or getting some cane metal and doing a more traditional style cage for it.

    I ended up having some issues with dropping the voltage down and consistency, so I made a series regulator using some zeners and an NTE94 transistor I got at a hamfest for free along with a heat sink I didn't think I needed from yet another hamfest I'm glad I got anyways. :) I hooked up my HW-12 up today, and it seemed to work when hooked up to the signal generator (it's AM, but it seems close enough to do crude tests :)) The radio is way more sensitive than my SX-43 is, enough so I was able to get down to -93DBm on the generator and still hear it.

    I need to get an antenna up, align it and start making use of my freshly minted license. Well, I need to get a mic set up on this HW-12. Would any general CB type mic work on it or do I need something more specialized? I have one amplified mic and a bunch that aren't.
     
  8. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    Wlw You are making good progress on this project.
    Good Deal. :)
     
  9. K6BSU

    K6BSU Ham Member QRZ Page

    If you are going to use a Dremel cutter to make lands on a Cu-clad, make sure those gaps are very wide! Inspect with a high power magnifier. (prevents later smoke!)

    It is actually easier to forget copper clad, and mount parts on plain epoxy board, through holes you drilled. . A dab of 5-min epoxy will hold parts until interconnected. Interconnect with pieces of solid insulated wire.
     

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