• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

hammond 1650

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puginfo405

Member
2009-08-25 9:01 am
  • #1
    i did not find any rules for the PT and OPT orientation on a top and down position. all the rules of thumb on here are applicable to side by side or single plane placement (which goes by 90deg out in the core orientation). im in a position where i need to stack the OPT right above the PT on dual plane.

    although 90deg placement of the core is still observed, is there anything else i need to watch for? the OPT is hammond 1650R (above) and PT (custom) is about 280VA. they are practically resting on each other with a heavy gauge (2mm) plate in between. any problems here?

    thks for any help.
     
    kevinkr

    kevinkr

    Administrator
    Paid Member
    2004-09-14 4:09 am
    Boston, Massachusetts
    www.kta-hifi.net
  • #2
    Even placed at right angles there is some potential for induction from the power transformer into the OPTs. I would mock something up and make absolutely sure that magnetic coupling is not a problem before you build this amp.

    You'll need to put some sort of load on the PT (I'd just use silicon diodes, an electrolytic cap and a large load resistor across the HV secondary drawing the typical operating current of the amp) and orient the OPTs in the proposed way and measure the voltage induced into the secondary with resistive load. More than a mV or two is cause for concern.
     
    P

    puginfo405

    Member
    2009-08-25 9:01 am
  • #3
    kevinkr said:
    Even placed at right angles there is some potential for induction from the power transformer into the OPTs. I would mock something up and make absolutely sure that magnetic coupling is not a problem before you build this amp.

    You'll need to put some sort of load on the PT (I'd just use silicon diodes, an electrolytic cap and a large load resistor across the HV secondary drawing the typical operating current of the amp) and orient the OPTs in the proposed way and measure the voltage induced into the secondary with resistive load. More than a mV or two is cause for concern.
    Click to expand...

    thks for the input Kevin. so what im understanding here is,
    - power up the PT with actual load
    - stack PT and OPT cores at 90deg off
    - load OPT secondary with abt 8ohm resistor (primary open)
    - measure voltage at OPT secondary (zero is the target i guess)

    cheers
     
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