Connect with us

What does the "C/W" on this transformer data sheet stand for?

Discussion in 'Datasheets, Manuals and Component Identification' started by John Smallberries, Jul 29, 2013.

Scroll to continue with content
  1. John Smallberries

    John Smallberries

    Jul 29, 2013

    I have a data sheet for a Hammond 291BX (, and there's a line in it that says the following:

    Sec. Voltage (RMS) 660VCT @ 138mA C/W 50V TAP , 6.3V @ 3A / 5V @ 3A

    This transformer has three secondary windings: 5 volts, 6.3 volts, and 660 volts. The 660-volt winding is center tapped and also has a 50-volt tap on it.

    What does "C/W" stand for?
  2. techiesteve


    Jul 27, 2013
    I've no idea, other than a guess. 'Complete with' to indicate its a tap on the 330-0-330V HT winding rather than a separate winding as is often the case. The 50V tap would typically be used to supply a negative bias to the control grids of the push pull output valves in an amplifier.

  3. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Coupled with?

    Reading the title, I was all prepared to say "degrees C per Watt" -- But I can assure you that in this case it's not!
  4. shrtrnd


    Jan 15, 2010
    I don't know either, but I'll guess too:
    The 660VCT, is 600 Volt Center Tap,
    so I'd speculate 138mA C/W 50V TAP, might be 'Center/Wire'.
    Probably, only the mfgr knows for sure.
  5. MP4BJI


    Aug 25, 2013
    Transformer tap

    Sounds as it is a tap for providing negative bias. If it is a tap, you can tell its connection by comparing the overall winding resistance and the resistances to the tap from each end of the winding.
    Or you could just power it up and measure its voltage related to the other windings (be careful of the high voltages).
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day