BTI amplifier

Discussion in 'Amateur Radio Amplifiers' started by N2ZD, Nov 24, 2019.

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  1. N2ZD

    N2ZD Ham Member QRZ Page


    I have a BTI LK2000, with a peter Dahl transformer and a 3-1000z tube in it, I went physically thru the whole amp and and when I turn it on, it blows the houses circuit breaker.
    The fuses are all good and the proper size.

    I’m going to pull the tube and see if the amp fires up without it to rule that out to a degree.
    Then start checking the other goodies.
    The caps look like computer grade Mallory’s which bolt to the board and it uses ceramic bleeders it appears.
    Just figure I’d throw this out there to see if anyone had any ideas as it’s a pretty uncommon amplifier. It also appears to be the HD model and with the Peter Dahl it should be pretty stout.

    Regards Richy N2ZD
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Those were great amps as I recall.

    Never owned myself, but did use one at Steve's, W3BGN's contest station outside Philadelphia years ago when he invited me to be part of a M/M group in the ARRL DX. He owned it, and maybe still has it (don't know).

    3-1000Zs have not been manufactured in decades, so I hope the tube is good!

    I see you're on Static Island, which is only about 80 miles NE of W3BGN's place. If you have problems, maybe reach out to Steve and see if he can offer any advice.
  3. KU3X

    KU3X Ham Member QRZ Page

    If you need a tube and can't find a 3-1000, get a 4-1000. That's what most guys use rather than no tube at all.

  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    For sure. 4-1000's are way more available, and I even have spares for my own 4-1000 amplifier here. All "pulls" from broadcast stations 30 years ago and they work fine. Damned rugged tubes.
  5. N2ZD

    N2ZD Ham Member QRZ Page

    Thanks for the replies! would you think a shorted tube of this ilk is a common failure? This thing blows a breaker right after hitting the switch lol.
    I’m going to pull the tube in a little while and crank it over to see what she does. I’m guess the tube is “fubar” but we’ll see.
    This thing has 4000 Screws holding the cage on lol

    Regards Richy N2ZD
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Nah, I'll bet it's only 3995 screws.:p

    A shorted tube can do what you describe. However, so can a shorted rectifier or filter capacitor or lots of stuff.

    Certainly try the amp without the tube, and be careful. If it passes the "everything powers up fine without the tube installed" test, then yes, it's likely the tube is a goner.
    WA7PRC likes this.
  7. N2ZD

    N2ZD Ham Member QRZ Page

    Thanks, I’ve rebuilt quite a few amps over the years but I laughed when the breaker blew but not the fuse. I’m like dang that was fast!! Lol
  8. N2ZD

    N2ZD Ham Member QRZ Page

    No tube, hit the on switch and blew the breaker, so with the tube out it did the same thing. I’ll dig into the cap bank and rectifiers tomorrow and see what’s going on.
    The multimeter was set for plate KV and it did develop about 1000v on the meter before it blew the breaker, then bled down to zero. It’s got some big ass caps in there so I’ll change it all out anyway. I don’t know how old the caps are but they are radial caps with two bolts holding them to the board.
  9. W1QJ

    W1QJ Ham Member QRZ Page

    Same thing happened to me. A big home brew pair of 4-1000’s would blow my panel breaker but not the amp breaker 30 amp. I brought amp up slow on a Variac and no problem. I bought a brand new breaker and it was fine. You could have a weak breaker. Try bringing the amp up on a Variac. Or install a new breaker or a higher current breaker.
    N2ZD likes this.
  10. WL7PM

    WL7PM Ham Member QRZ Page

    yeah- yeah! Bigger Breaker. Plug it in to the dryer outlet !
    N2ZD likes this.

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