I suggest that you change the caps and the equalising resistors too!
Our Henry Tempo 2002A started making fizzing and crack noises some 12+
years ago during a contest. L:uckily at the time I had a spare
rectifier + caps + resistors bank which I substituted to keep us on air.
On further investigation we found that the 2W Carbon Composition
resistors that were supposed to be 470K were all over the place -
anywhere from 470K, 500K, 600K, 900K and one was > 2M - hence the
voltages across the caps were not equal and this lead to stress on the
caps which could have resulted in an explosion!
There are good quality, high voltage, high current Metal Oxide Film
(MOF) resistors which should be considered these days.
Mike G8TIC
On 24/12/2014 02:10, Alek Petkovic wrote:
BANG!
Yep. They were talking about the electrolytics.
Change 'em, before you have to change your underwear.
73, Alek.
VK6APK
On 24/12/2014 7:59 AM, John G3UUT wrote:
Sorry folks, are we talking about the string of smoothing
electrolytics or a ceramic RF filter cap here? I'm curious about
this as when I switched my 2m amp on recently which hadn't been used
for about a year there was a regular series of 'snaps', the frequency
of which gradually diminished as it warmed up. I was worried by this
but it didn't seem catastrophic and seemed to be improving with time
so I left the amp on. By the end of the contest the amp was usable
(typical) - I couldn't really use it earlier as the snaps put quite a
high level pulse of QRM into the RX path.
73 John G3UUT
On 23/12/2014 11:08, Andy Cook, G4PIQ wrote:
Oh yes. I heard this coming from one of our old Alpha 78s during
CQWW CW at 5U5Z some years ago. It did this for quite a few hours
and then in the middle of the night there was a big bang and the
room filled with smoke as one of the filter caps let go. It
certainly woke the operators up. I should change those caps now!
73
Andy, G4PIQ
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