Bill
Yours is the same as the S50 in catalog, just terminal arrangement
and marking are different. Plus the taps on the primary, for low line
voltage, high line voltage, probably.
The two 5000 V posts are the ends of the taps for 2500 and 2500
windings, and the two 6000 posts are the ends of winding at 3 kV each
with respect to ground. The center tap is to be used, as those
transformers were rated to be used in full wave center tapped
operation, 2 diodes for rectifier instead of a bridge of 4. If you
were to try and use the end-to-end voltage into a full wave bridge to
get much higher voltage, you may damage the secondary winding as the
center tap would float, supposed to be at chassis potential with that
iron. It was rated to work at 2625 or 2175 VDC output, when connected
to a two section choke input filter, with 300 mA DC ICAS rating. It
should not be used for 300 mA for 24/7 operation without cooling
down. But for intermittant ham transmissions, its probably fine for
that.
As others have probably said, the amperage on the 115 VAC side will
be dependent on the load, if you are running AM, CW, or SSB. Using an
L input filter as the transformer was intended, should result in
lower peak current. Knowing that you only have 300 mA and 2625VDC, it
could supply 787 watts intermittantly, which might be the DC input to
an amplifier of 500 watts output. For SSB it might be pushed a bit
for current, but the voltage would probably sag in response due to
the secondary and primary wire size. With 787 watts off a 115 volt
circuit, you would draw 6-8 amps, no more than some vacuum cleaners
in homes. That transformer is undersized for pushing a 4-1000A
tetrode to decent power. From what I am told, that tube can run
higher HV. You will find it a bit low on voltage for that, although
it will work in a pinch, with about 500 watts output at lower gain.
73
John
K5PRO
>Message: 3
>Date: Tue, 8 May 2007 19:23:03 -0400
>From: "Bill Otten" <harpman54@tampabay.rr.com>
>Subject: [Amps] Transformer question...
>To: <amps@contesting.com>
>Message-ID: <001001c791c7$d3f77d80$6701a8c0@Home4Bill>
>Content-Type: text/plain; charset="iso-8859-1"
>
>Hi, I'm new to the group and just learning a great deal reading
>through the archives of this list. One question I have: I was given
>a United Transformer model S50 (called the special series in the
>only reference I could find online...a 1962-63 catalog). The S50
>listed there isn't the same as the one I have. THAT one was listed
>as 115volt primary with secondaries of 3000-2500-0-2500-3000.
>
>The one I have has the two 115 volt primary taps and a center tap,
>but there are 2 connections on top marked 5000volts and two more
>marked 6000 volts. I haven't a clue what the DC amperage rating
>might be on this amp, nor do I have any clue as to whether it would
>power an RF deck. I think my concern would be the pull on a 115 volt
>circuit to run 6000 volts out. Size is about 10" high by 9" wide by
>7" deep. Plenty heavy.
>
>Bottom line: I'd appreciate any insight into this transformer and
>whether it would supply an amp somehow. It tests fine. 10 volts in
>and about 470volts out on the 5000v taps. I can't recall the results
>of the 6000volt taps but they were a bit higher than the 5000 volt
>taps.
>
>I have the RF deck already complete...a very nice 4-1000A, just got
>to deal with getting a power supply to fire it up.
>
>Thanks!
>
>Bill
>KC9CS
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