>I have an old BTI LK-2000 that I'd like to revive, condition unknown.
>Could someone point me to a FAQ/etc. on the judicious procedure to bring it
>up slowly to start?
** -- Brad Thomas' design was basically ok for its day. However, a few
circuit improvements are in order.
One problem with the LK-2000 is that the HV electrolytic filter caps run
on the ragged edge of V breakdown. Unless the HV filter board has been
modified for 10, 450v units, I would replace the 8, 450v caps with 8.
500v Panasonic/Matsushita caps from Digikey. I would also use Panasonic
100k-3w MOF for the equalizer resistors to reduce heating of the filter
caps.
- Another problem with the LK-2000 is that a 3-1000Z has c. 0.7 pF of
feedback C. By comparison, a 3cx1500A7/8877 has 0.1pF of feedback C. To
improve VHF stability, a lower VHF-Q parasite suppressor is in order for
the 3-1000Z. However, this mod will reduce 10m output by c. 2%. If the
3-1000Z ever needs replacement, Eimac's new 3cx1200Z7 has only 0.07 pF of
feedback C, so it is less squirrelly. // The instability problem can
also toast the 10m, 15m, and occasionally the 20m bandswitch contacts.
[see
http://www.vcnet.com/measures/BTI.bsw,JPG
on my Web site].
gud luck, Scott.
Rich, AG6K, 805-386-3734, www.vcnet.com/measures
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