Greetings topbanders. . .
While CQing early this morning I began noticing a faint but troubling smell in
the shack. It smelled like over heated wiring or electrical components. It
continued to get stronger as I realized the odor was coming from the Alpha 99
amp. Indeed, a few moments later it tripped out. I dug into it this afternoon
and discovered a leaky 75 pF/6 kV cap which is one of five such caps in a
parallel bank that is pulled in on the band switch to achieve tank resonance
only on 160m. I have removed the bad cap making the amp operational once again
with the air variable tuning cap making up the lost C (and there’s still a
little C to spare on the air-variable). After some searching I cannot find a
75 pF/6 kV cap. Mouser does not have anything even close in terms of the high
voltage rating (hopefully I didn’t something). The closet thing Newark has is
47 pF which I have ordered. I’m guessing the 47 pF is probably OK but how
important is equal current distribution across the five caps? Maybe I don’t
need to be concerned about it? If I really do need the correct 75 pF/6 kV cap
does anyone have ideas of a source? Replying privately is fine. See you
all in the Stew. 73. . .Dave, W0FLS
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
|