Bob -
Looking at your photo again, I'm assuming the cap at the lower right is
the one you are concerned about. Are you sure it's 'blown'?? They are
coated with wax, and when heated the wax tends to accumulate on the
lowest point, and is much thicker and has that 'brown' color. It' VERY
unusual for a disc ceramic to fail unless it's physically damaged.
Also, that one is on the lower RF side of the feedthrough, meaning it
shouldn't see much if any RF over and above the AC filament voltage.
That is a 'garden variety' disc ceramic cap, 0.1 uF, and the 'Z5V' code
means +10° to +85° operating range, and +20 / -80% capacitance change
over that range. Interesting that yours seems to be marked 'backwards',
i.e., +80 / -20%. The most common is 'Z5U' which is a +20 / -55%
variety. The absolute value isn't all that important.
The voltage isn't marked, but most disc ceramics of that type/era were
600V DC unless marked otherwise. These days they are typically lower
voltage, 50 or 100V DC, which would still be more than high enough.
Any of the usual suspects, Mouser, Digikey, Allied, etc. should have
plenty. Even better, if you have any sort of electronics surplus stores
left, they would have boxes of them. Hamfests are also a good source.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
ROBERT SMITH wrote:
Hope I'm not getting into trouble posting this again. I have a late
model L4B amp- serial number 6122. I'm new to this Drake and vintage
gear so please bear with me. I blew a Ceramic Disc capacitor on the
L4B C -26, Stamp .1 Z5V+80 -20. This goes to the RFC 2 then
to one of the 3-500Z filament. It has to have high amperage thru it
I would image, plus what voltage? Tube info says 5 volts on the filament.
So what I would like to know where I could fine a replacement for the
blown one and a couple extras. Part number ect. I have enclosed
a picture of the blown cap. I think this is used for keeping RF away
from croke and filament??
Thanks
Bob w0vu
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