Posted by Phil Townsend (A) on January 29, 2007 at 06:48:17

In Duncan Amps PSU there is a place to enter the Ohms for the transformer secondary...
What should I use for the MQR 5500???

Phil
Santa Fe
Phil
Santa Fe

• Measure it and calculate - VoltSecond 19:31:26 01/29/07 (0)
  In Reply to: MQR 5500 and Duncan Amps PSU...HELP!!! posted by Phil Townsend on January 29, 2007 at 06:48:17:

  Effective DCR secondary for PSUD II
  = Rsecondary
  + Rprimary * [Vsecondary {unloaded}/Vprimary]^2

  You'll also have to be very very carefull and measure the unloaded secondary voltage.
  Or set V secondary unloaded
  = Vsecondary rated
  + I rated * effective DCR used for secondary in PSUD II
  and ignore the difference between Vsecondary unloaded and loaded in calculating the effective DCR.

  Example:
  Vrated secondary 230V rms
  Vrated primary 115V rms
  DCR secondary 100 ohm
  DCR primary 20 ohm
  Irated secondary 200 mA

  DCR for PSUD II = 100 + 20 * (230/115)^2 = 180 ohm
  Vsecondary for PSUD II = 230V + 180 ohm * 200 mA = 266V
  (When checked
  [115V - 20 ohm*0.2A*266/115]*266/115-{100 ohm*.2A) = 224.6V loaded
  for 5.4V error out of 230V)

  If you want, you can iterate a couple times to get a better value, personally, I wouldn't. But for perverse curiosity I'll do one iteration:

  DCR pass 2 = 100 + 20 * (266/115)^2 = 207 ohms
  Vsec pass 2 = 230V + 207 ohm * 200 mA = 271V
  (When checked
  [115V - 20 ohm*0.2A*271/115]*271/115-{100 ohm*.2A) = 228.8V loaded
  for 1.2V error out of 230V)
  
  
  Play safe and play longer! Don't be an "OUCH!" casualty.
  Unplug it, discharge it and measure it (twice) before you touch it.

  . . .Oh!. . .Remember: Modifying things voids their warranty.
  
  

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• Re: MQR 5500 and Duncan Amps PSU...HELP!!! - Gordon Rankin 14:29:47 01/29/07 (0)
  In Reply to: MQR 5500 and Duncan Amps PSU...HELP!!! posted by Phil Townsend on January 29, 2007 at 06:48:17:

  Phil,

  First off using the 5500 for mono Bugle's would be a little more than required.

  I looked to see if I had some extras but I don't. I hope Mikey will make more of these since I still use them.

  You may want to go too like a hammond 300 series. Though many of those have really high current ratings and are way too much for the bugle also.

  I might suggest using like a 6V4/6X4or5 and using like a PGP8.1 for mono 45 amplifiers.

  Thanks
  Gordon
  
  J. Gordon Rankin
  
  

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• Re: MQR 5500 and Duncan Amps PSU...HELP!!! - mqracing 08:01:48 01/29/07 (0)
  In Reply to: MQR 5500 and Duncan Amps PSU...HELP!!! posted by Phil Townsend on January 29, 2007 at 06:48:17:

  Hi Phil:

  As Bas suggests... best would be to measure one. From memory I think the hv sec dcr of this trans is somewhere in the 250 to 275 ohm range.

  And a quick note... if you don't have a 5500 or access to one already... please be aware that we are no longer making this part number.

  MSL
  
  

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• Do you have a meter? Best would be to measure them. nt - Bas Horneman 07:48:54 01/29/07 (0)
  In Reply to: MQR 5500 and Duncan Amps PSU...HELP!!! posted by Phil Townsend on January 29, 2007 at 06:48:17:

  ..nt..
  To infinity and beyond!!!
  
  

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