Heathkit HA-14 Restoration thread

Discussion in '"Boat Anchor" & Classic Equipment' started by WA6MHZ, May 23, 2014.

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  1. AF6LJ

    AF6LJ Ham Member QRZ Page

    Mouser has them...
    http://www.mouser.com/Search/Refine.aspx?Keyword=Hammond+die+cast+boxes
    Here are some ideas...
    http://www.mouser.com/catalog/catalogusd/646/2116.pdf

    Four inches by four and a half inches.
    You will need holes for the wires, they are half way between the four and a half inch centers.
     
  2. AF6LJ

    AF6LJ Ham Member QRZ Page

    Ah Micor base station meters, I have those exact meters.
     
  3. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    WE use those boxes here at work on company products. They are very sturdy, but also very difficult to drill. WE have to send them out to a Machine shop to MILL out holes. So other than a tiny hole they are impossible to drill. They have all sorts of slots inside for PCBs, SO I will stick with the original plan of using the Aluminum angle brackets and aluminum bar. The bar will go under the xfmr probably at a right angle to where the leads come out I can file the bar if necessary. I need to find two 8A Circuit breakers now too. They were available CHEAP at the EL Cajon Junk store!! OH HOW I MISS THAT STORE!!! don't know if I need a fan for the PS. This will be an Ideal project for the HOMEBREW CONTEST coming up in November. I always automatically win my catergory cuz I am entered in the WA6MHZ Catergory which doesn't compete against other club members as it is no contest! No one else in the club has access to a World class Manufacturing facility (so it wouldn't be fair for them to try and compete!) The club used to issue nice wall plaques to the winners but now they are poor and don't have the budget for it!
     
  4. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    Why would a Micor use a 3000V Power supply?
     
  5. W9GB

    W9GB Ham Member QRZ Page

    An Electrical Conduit 2" Punch has an actual O.D. of ~ 2.416 inches.
    That will get you close -- that a file, reamer, and nibbler can usually finish the enlargement.

    The 250 watt (1/4-kilowatt) Micor base station used the Eimac 8560AS ceramic radial beam power tetrode ??
    Maximum plate voltage for that tube was 2,000 VDC, maximum plate current 250 mA.
    http://www.cpii.com/docs/datasheets/75/8560AS.pdf
     
    Last edited: May 26, 2014
  6. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    Thanks!!! I will look for that! I tried a circle cutter once but it was designed for WOOD (cutting holes in doors for doorknobs)
     
  7. AF6LJ

    AF6LJ Ham Member QRZ Page

    Micor upright high base station / repeater.
    They built a number of high power tube base stations / repeaters.
    For example they built an 800 MHZ repeater that used a 3CX400U7 in a cavity tuned amplifier.
    Very conservatively rated at 125W. Truth is you had to work to keep them from running 150-175W.
    That amp used a 1500V feroresonant power supply, had a really big transformer.........

    They also made 900 MHZ paging transmitters that used 8640s that would put out 350W.
    All that stuff is solid state now. I have worked on that stuff.
     
  8. AF6LJ

    AF6LJ Ham Member QRZ Page

    Are you sure you are not talking about the stainless steel versions.
    The aluminum ones are easy to drill, it is like drilling a hole in a cube of butter.

    You might want to look again at the second link and I think you will find you can find boxes of the proper size that don't have slots.

    Don't drill too many holes yet, we haven't discussed price...
     
  9. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    Comparing the SB-200 to the HA-14, they use almost the same exact grid circuit with the only difference being a 1.5 ohm resistor coming off the bottom of the 20uhChoke/3.3K resistor junction with the Relay. then there is a 33 ohm to ground to key the relay. SO it would be an easy modification to insert a 1.5 ohm resistor in the line between C6 the .02 uf cap and the C8 the 2uf 150V cap. From that point I would run a wire to Pin 4 of the Power connector which is currently unused. that is the point I can monitor the GRID CURRENT which would be just like the SB-200 then. STILL Hafta do some circuit mods to compensate for the Meter change. Probably will use the HV meter and have it set to 0-300mA full scale to match the meter calibration. I have a label make machine here at work I can add lettering on the meter face to indicate Grid Current. It is probably better to watch the Plate current and grid current at the same time instead of HV and Grid Current. So the HV will become a dual use meter. Alotta KIRCOUGHS LAW USE ahead to figure out resistor values!!!
     
  10. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    Well I don't expect u to gouge me on it. Is it worth $100 to U?
    I had another ham offer me one for $100 but it would have taken $50 shipping to get it!
     
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