Heathkit HA-14 Restoration thread

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

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  1. WC5P

    WC5P Premium Subscriber QRZ Page

    Many years ago, a friend of mine brought me an HA-14 to play with for a few days. I was quite impressed with it. Very easy to tune, just peak it and set the drive where you want it. The lack of a load control was not a problem at all, assuming reasonably matched antennas. Sure did run hot though. You could probably toast your tortillas on top of the cabinet. That should be a fun little amp when you get it going.
     
  2. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    for the 4CX250 U would be best to use separate transformers like I did in the 6M KILOWATT I built (that never did work) Never did figure out why, it was built perfectly and the tuned circuits all dipped. for the 4Cx250s U need a regulated screen supply Think I had a separate transformer for it. It was very tricky cuz I had to build various time delay circuits. THERE is a 2 minute warm up on the filaments before U can apply HV to the tubes and U have to make sure U don't have screens only or it will blow the tubes. So there was quite alotta logic circuits and 555 timers I had to construct to make it. That all worked. What didn't was RF OUtput. think it only put out about 100W or so. Thats no good for a KW LINEAR!! So it got put on the "maybe I'll look at it someday again shelf." that project caused me to quit the ARCEC CLub for a year. The Homebrew contest judges awarded 1st place to helically wound antenna over the 6M KILOWATT!! so I said PHOOEY on the club for a year and during that time is when all the fuss ensued, where the President was ousted by a COUP and it was in total turmoil until I took it back over. I restored order, mended the fences and brought peace back to the community. So now everyone is happy again and the club is growing once more. We lost over half the membership in that COUP! They are slowly coming back and we see more and more at every meeting. But it will be a hard climb to get it to where it was 10 or 15 years ago! But atleast there is PEACE in the community again. Some meetings were so out of hand U thought there was going to be a RIOT!
     
  3. AF6LJ

    AF6LJ Ham Member QRZ Page

    We should pull out that amplifier and see what is wrong with it.
    That won't be so hard to troubleshoot.

    I have a screen voltage transformer that would also supply low voltage for the control circuits if I chose to incorporate them.
    It is not hard to remember to wait a few minutes before applying plate voltage.
    Using the voltage divider method to provide screen voltage is actually best, because if the plate supply fails the screen goes to zero also. While that is not a real elegant way of doing it, it is fool proof.
     
  4. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    I forget what I did, I got it here in a a box. The AMP itself is on display in the West WING of the Museum It is very compact, about the size of a toaster laying on its side, with full metering too! IT really was an outstanding project. Too bad it didnt work!
    U shoulda come today to the RAdio HOSPITAL, the boss didn't show up. Peter came over and delivered the flyers for the Santee STreet fair!
     
  5. AF6LJ

    AF6LJ Ham Member QRZ Page

    Roommate is out of town until late Monday night.
    Maybe next weekend or the first weekend in June.
    Is the control grid bias supply in that amp adjustable?

    Oh that is right there is an event next weekend....
     
  6. N2EY

    N2EY Premium Subscriber QRZ Page

    How can sonmething be "an outstanding project" if it didn't work?
     
  7. AF6LJ

    AF6LJ Ham Member QRZ Page

    Here is the much discussed SB-200 transformer which has been sitting in the same garage for the last twenty years, so there is some surface rust which is easy enough to clean up...

    There is a little history behind this transformer; it is perhaps the only SB-200 transformer to be purchsed from Heath without a defective transformer traded in, at the time it cost $63.00 My ex walked into the Heath retail store back in 1973 and bought this along with some SB-200 tank circuit parts. a Load cap, tune cap, and a blocking cap (door knob type) The guy at the counter was the resident ham (I believe his first name was Herb) He took down the order and too, the money. All the parts showed up at once and my Ex went and picked them up. That was a lot of money back then, the plate transformer and the loading cap made by TRW cost just about the same....

    Two weeks later my Ex went back in to pick up some small parts for a project (the same CB amp he bought the heathkit parts for.) he got to the couter and Herb informed him of all the HELL he caught for selling an SB-200 transformer and not receiving a defective one in return. How do I know this story is true? I've seen the invoice for the parts.
    Well here are some pictures............
    [​IMG]

    [​IMG]

    [​IMG]

    As you are aware these transformers were potted in pitch or some similar compound, I don't expect the thing to be full of moisture. Nonetheless this is an old transformer despite it having less than a two hundred hours of actual use..
    My ex was the type that would build something to prove ether that he could or some concept then after using said project for a while it would usually end up being partially cannibalized for another project.
     
  8. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    While it is sitting there on the desk, can U measure the distance between the holes, from center to center of the oblong holes, so I can start designing the chassis. It is going to be a very heavy unit. That is not the same transformer they used in the HP-24. Yours is easier to mount with the mounting wings on the bottom. but those will hafta be bolted to some serious metal to keep from warping. I don't know what kinda chassis U were talking about a few posts back, but my idea using the aluminum angle pieces and bar is easy to fabricate here cuz I have a cutoff saw that goes right through it like butter. Then I have the SHEAR in the back and Brake. SO this is the finest Homebrew shop around. Just wish I owned the place! A friend from the DX Club is on his way over for me to Field Check some DXCC QSLs! SO I threw the TR-4 off the table for now.
    Once I get the chassis designed I can order the MOUSEY WOUSER Parts. I will put them on a Radio Shack perfboard that will fit in the other side of the chassis from the xfmr. It will be way way unbalanced A wiser move might be to make it longer and put the transformer in the center SO I will hafta build up the sides after all to put in the meters. I have a pair of meters I had planned on using for the SB-200 project that fell through. Some projects just never get finished.
     
  9. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    It almost worked! That is closer to than not WORKING at all!

    It might have been my test set up too. I was trying to drive it with a Lafayette HE-45 which might have been too lame.
     
    Last edited: May 25, 2014
  10. WA6MHZ

    WA6MHZ Subscriber QRZ Page

    Here is the meters 500uA FS on them, will hafta calculate the meter resistance.
    so it will be tricky to make the appropriate voltage dividers for them. The most painfull part will be cutting the 2 5/8" holes to mount them
    [​IMG]

    Still don't know what to do about the grid meter
     
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