Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ALBATROS1234 on May 17, 2018, 07:58:31 pm

Title: i have a perfect power transformer but the high voltage winding is too high. can
Post by: ALBATROS1234 on May 17, 2018, 07:58:31 pm
next build i want to do is a supro 6424 and the transformer voltage requirements are approx 305-0-305(to 320-0-320)@150ma. i have a great transformer with both 5v 6.3v at 3amps plus and a 200ma high voltage which measures 400(ish)-0-400 is it feasable to drop basically 100volts with a resistor? i tryed to hook the pt to a power supply i had with a bridge and normal value caps and resistors and got just over 540vdc. granted i will be using a 5y3 so that should be approx 400 x 1.2=480vdc right? in the above described power supply test i placed a couple resistors on the +dc leg and found i got approx 120vdc drop with a 2.7meg 3watt. the question is am i ok using a large value resistor to drop this much voltage imediately after a 5y3 ? the sluckey model 24 supro schematic wants 350vdc on the first node of the ps so by my approximation i would have to drop 480vdc to 350 either right after the 5y3 or perhaps i should drop what i need on each leg to get proper voltage outputs for each of the 3 nodes 350 at node 1 340 at node 2 and 288 and node 3. i guess theorhetically i could put a dropping resistor in at the output nodes of the ps if that would be better for the 5y3 etc.
Title: Re: i have a perfect power transformer but the high voltage winding is too high. can
Post by: sluckey on May 17, 2018, 08:16:42 pm
Don't do it. Get a more suitable PT.
Title: Re: i have a perfect power transformer but the high voltage winding is too high. can
Post by: ALBATROS1234 on May 17, 2018, 09:27:41 pm
is it gonna screw with current supply or perhaps the 5y3 as i suspected? in theory it seems like it could work but something was gnawing at me to ask the pros. my other options with what i have on hand is to use a bridge with one of my lower voltaged no ct xfrmrs but i think my best scenario with that i will be slightly shy of the voltages suggested in your schematic . like i know i can get 290 to 300vdc at node 1 but thats 50volts less than requested. although i built a killer sounding 12ax7/12aq5 amp with only 180vdc at 1.6 watts. guess ima save my pennies.
Title: Re: i have a perfect power transformer but the high voltage winding is too high. can
Post by: ALBATROS1234 on May 17, 2018, 10:14:20 pm
screw it just bought a 315-0-315 hammond @160ma i dont know what ima use this other beast for.
Title: Re: i have a perfect power transformer but the high voltage winding is too high. can
Post by: USAampsRus on May 23, 2018, 08:36:09 am
Quote from: ALBATROS1234 on May 17, 2018, 10:14:20 pm
screw it just bought a 315-0-315 hammond @160ma i dont know what ima use this other beast for.

sell it on Ebay or Reverb.