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In Duncan Amps PSU there is a place to enter the Ohms for the transformer secondary...
What should I use for the MQR 5500???
Effective DCR secondary for PSUD II
= Rsecondary
+ Rprimary * [Vsecondary {unloaded}/Vprimary]^2You'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 mADCR 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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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.
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.
..nt..
To infinity and beyond!!!
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