This AC power transformer is from a long ways back in time, I think it was some tube Sansui preamps but the memory is not so good these days!
Nice compact transformer if you need to make your own tube gear, preamps in particular
AC POWER TRANSFORMER
Country of origin is probably Japan (but not stated on the transformer)
Please be aware that there is no mention of International or Australian safety standards on the labelling
ID labelling on the transformer is:
5T-741 (primary side)
39.12.24 (side of the frame)
No other markings other than the voltages at each terminal
Type: E iron core
Primary & Secondary are fully isolated - this is NOT an auto-transformer
All terminals are solder tag
One side of the transformer has one end of the primary winding (yes, just one end) and the taps are: 240V, 220V, 117V, 110V, 100V AC
Unusually, the 0V of the primary winding is physically over on the other side of the transformer, next to the secondary 0V
The secondary has 0-6.3-11-107V output markings
These are all marked on the transformer insulation card/paper material ... please read my test results below to see what I actually measured.
Current on the secondaries, here I would only be guessing - but it will not be high, enough for a tube heater or two (6.3V) and perhaps 20~50mA for the 97V AC anode supply. If this 97V is connected to a full wave bridge with filter caps, something around 135~150V DC should be possible and a typical 12AUX7 could draw up to 3mA per tube, depending upon bias conditions - well within the scope of this transformer.
DIMENSIONS:
61mm wide x 50mm height x 62mm depth
The mounting has been modified by the equipment manufacturer, the mounting on one side has been cut away and the other mounting has been bent through 90 degrees so some work may be required to mount this transformer in other equipment.
WEIGHT:
775g
TESTING:
I made basic resistance tests on all windings but tested ONLY using the 240V input winding.
Secondary outputs measured
97V AC
12V AC
6.6V AC
The only winding that seems to be about 10% down from the marked voltage is the 107V terminal.
These measurements were all made under NO LOAD conditions.
I also checked the insulation resistance between both the primary and secondary windings to the transformer frame - here I am reading infinity using a 500V megger.
COSMETIC CONDITION:
USED
Clean
ALL solder terminations are secure and undamaged
NO damage to the insulation
This transformer is now safely packed into a sealed clear plastic packet, waiting to do some work once again
