I had a questionable HV transformer in an SB-220. I applied low voltage (6
or 12 VAC) to the secondary to see if I got voltage across the primary. No
big voltages here.
I say without knowing that your secondary resistance ought be far less than
1K.
73, Mike N4NT
----- Original Message -----
From: "John (KE5C)" <ke5c@hot.rr.com>
To: "Ten-Tec Reflector" <tentec@contesting.com>
Cc: "Steve Bosshard (NU5D)" <bosshard@gmail.com>
Sent: Wednesday, April 12, 2006 2:32 AM
Subject: [TenTec] anyone lose a centurion hv xfmr?
the short question is, does anyone know the approximate secondary
resistance of
a centurion hv xfmr? the reason i want to know is that i am trying to
determine
if i've lost my centurion hv xfmr without actually measuring the secondary
voltage.
the full story is that i had the amp on but not in use. i thought
something
fell down in the shack due to an unusual noise. everything looked in
order, but
then i noticed the amp was off and one of the line fuses had blown. i
took the
cover off and saw nothing unusual and decided to replace the blown fuse
and put
the cover back on. this seemed to bring the amp back to life, so i put it
in
line and turned the orion down to about one watt and keyed. all seemed to
work
(i am using a qsk loop), so i advanced the drive to 20 watts and
fortunately i
was monitoring grid current because it went sky high in a hurry. i
switched the
meter to hv, and there was none. after some *extremely* careful
troubleshooting, i determined the hv primary is receiving 230 vac, but i
have no
way (and little courage) to try to measure the transformer secondary
voltage.
however, the secondary resistance (with the rectifier board connected) is
initially more than 1k ohm. the apparent resistance falls with time due
to the
capacitors charging via the vom, and reversing the test polarity restores
the
resistance to more than 1k ohm until the other bank of capacitors start to
charge. this also suggests to me that both sides of the full wave bridge
are
intact. hence, i am thinking i may have an open hv xfmr secondary,
although why
would that blow a fuse???. i don't know what the xfmr resistance should
be, but
certainly less than 1k, right?
thanks for any comments, john
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