UTC CG-300 Pinouts??

Discussion in 'Tube Audio' started by zekk, May 29, 2011.

  1. zekk

    zekk Active Member

    Hi Folks,

    Can anyone please help me to figure out the variable primary connections?

    Pri: 0v, 105v, 115v, 220v, & 230v.

    Sec: 625v - 515v - 0v -515v -625v.

    Data sheets does not show pin connection!


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  2. PakProtector

    PakProtector AK member

    I suspect the secondary is in two separate pieces, and likely the primary as well. One bit of primary will be 0-105-115 and the other 0-115 so the entire combination of input voltages can be configured( ex. the 220 is created with the 0-115 connected in series with 0-105 of the first bit I think ). Now the secondary is likely created by putting the two bits in series. Now if that is the case you can make a 615-110-0-110-615 secondary by reversing the polarity. Perhaps useful for creating a negative rail bor either bias or a cathode follower...:)

    See what is connected to what with an Ohm meter, the primaries will be low compared to the secondary and there *MAY* be a separate tap for grounding the core.
  3. zekk

    zekk Active Member

    Thanks, Douglas!

    Using a variac to check out the pins, it's confirmed that the sec. taps are 7 to 11 at 625-515-0-515-625 respectively.

    Applying 105v to pin #1/#2, #4/#5, pins #7-9-11 reads 625-0-625v.
    The same 105v to pin #1/#3, #4/#6, pins #7-9-11 reads 515-0-515v.

    So, I've two pairs of primarys.

    If I series the primary for a 230v supply, will I be getting a doubled voltage across #7 and #11, eg: 1250-0-1250v? :eek:

    Regards, Zekk.
  4. zekk

    zekk Active Member

    ... just answered my own question!

    By connecting pin#3 and #4 together and applying 230vac to pins #1 and #6, I got 625-515-0-515-625v on pin #7 to #11 respectively.

    Thanks all for watching.

  5. PakProtector

    PakProtector AK member

    But you can arrange a 220 connection and apply 120V to it and deliver a little more than half that voltage. It will cut the volts/turn and make it radiate less which may be useful in a lower voltage design a typical linestage would use.
  6. zekk

    zekk Active Member

    Thanks again, Douglas!

    I'm building a SEUL TT22 with EL802 as driver.

    So, needs high voltage !

    Will post pics and schematic when ready.

    Regards, Zekk.

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