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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