Triad AO-3039T Output Transformer

[andYz00m]

assgasgrass nobody rides for free

You're killing me with these zingers. Im staring at the screen using maximum brain power trying to apply my basic understanding of the math and theory and BAM you throw this in.

 

[dougsta]

Nice! Thanks Doug!

always wondered about the ma for this #50,

extrapolates from that graph to about 1.5ma,

View attachment 88445

While working on my transformer calc program I revisited my extrapolated AWG chart.
I must admit to have had the correct amount of single malt (If it's not Scottish, it is crap!) for inspiration the night I made the 1st chart but too much for my organic calculator, C2H5OH induced leakage of the axons leading to my neurons receiving a -20bB cut...
Those neurons are dead to me now, anyhoo, today with a clear head I converted the AWG axis to log scale and up popped a nice straight line, the 1.5mA sits bang on the line too, I'll drink to that.

 

[CJ]

wire changes from old to new, this chart is kind of in the middle>

 

[CJ]

and this one from RDH4, it has different stuff, like how thick the insulation should be for various gauges

 

[CJ]

wrapped 3600 turns of #38 around the old former and plopped it onto the old
core to get inductance for the data sheet,

reads

41 Henries @20 Hz
36 h @ 100 Hz
25 h @ 1 K Hz

inductance curves are always flatter for a gapped core, this is one of the benefits, stable permeability.

once you pull apart a butt stacked EI core, you will never get it back to where it was due to burrs from the varnish, and other things that aging causes, rust, deformation,

i found this out during a rewind an an old Masco output transformer for a harp amp.

so we are going to bump these ratings up to 50 H at 20 Hz and call it good.

the rewind now has 100 H so bass response should be better.

DCR was 684 for the #38 AWG we used, so most likely Triad used #39 AWG. This wire is also used in their other outputs like the HS-50.

entering the inductance value into the lamination spreadsheet for EI 75 yields a perm of 700 which was typical for non grain steel back then. It might have been 800 before magnetic aging, no way to tell now.

testing the old core with the test winding>

 

[dougsta]

wrapped 3600 turns of #38 around the old former and plopped it onto the old
core to get inductance for the data sheet,

reads

41 Henries @20 Hz
36 h @ 100 Hz
25 h @ 1 K Hz

inductance curves are always flatter for a gapped core, this is one of the benefits, stable permeability.

once you pull apart a butt stacked EI core, you will never get it back to where it was due to burrs from the varnish, and other things that aging causes, rust, deformation,

i found this out during a rewind an an old Masco output transformer for a harp amp.

so we are going to bump these ratings up to 50 H at 20 Hz and call it good.

the rewind now has 100 H so bass response should be better.

DCR was 684 for the #38 AWG we used, so most likely Triad used #39 AWG. This wire is also used in their other outputs like the HS-50.

entering the inductance value into the lamination spreadsheet for EI 75 yields a perm of 700 which was typical for non grain steel back then. It might have been 800 before magnetic aging, no way to tell now.

testing the old core with the test winding>

View attachment 88523

CJ, I don't know if you've posted details about testing before, but what's the bare minimum test gear needed to do some testing like this?

There's an old tube audio signal generator in the photo, could this be home brewed? eg take a 1Vrms sine out of an old Win7 laptop running REW and feed it into a pre amp/power amp stage for, eg a 1-10Vrms sine wave.

I have a DMM (rms) and a CRT dual ch scope.

Doug.

 

[CJ]

ok this thing is all pruned up and ready to go>

 

[CJ]

done with the Wake and Bake,

hadware keeps lams and gap tight during processing,

spar varnish, non-water based used for dipping, 8 hrs at 200 F ,

neighbors think i'm cookin crack at night,

wandering around the back yard with a flashlight at 2 am does not help,

 

[CJ]

habit from the transformer shop days, round screw head goes on the high voltage side.

this does not matter at300 volts, but at 30 KV like some of the stuff we used to build, the engineers did not want any sharp edges on the business end of the xfmr, due to the possibility of corona developing especially when hi-pot testing..

 

[CJ]

ship it!

 

[Whoops]

Great Thread,
Thank you CJ

 

[beatnik]

round of applause !!!

 

[andYz00m]

Humbled and grateful!! Thanks, CJ.

 

[CJ]

your welcome.

i am worried about the power transformer for this preamp, if the wire in the pwr xfmr is in the same shape as the wire in the output, then it might be a good idea to start sourcing a replacement, possibly a toroid type if hum is a problem, you will be able to tell if hum is an issue when you fire up the unit with the new output transformer..

 

[andYz00m]

Triad R-3A. Looks like I can get another one for ~50$. Or probably find a suitable modern replacement. The values seem pretty standard.

Voltage on the heater secondary is (2.7VAC/3.8VAC).

The higher votage section is 263VAC

 

[Disco Volante]

Love the Funk. Digging out my 60's Tektronix scope/generator today..
Nice work, kinda suspected you'd have a bobbin ready on a shelf for that;-)

 

[solkatten]

Really nice work

 

[Fdieck56]

done with the Wake and Bake,

hadware keeps lams and gap tight during processing,

spar varnish, non-water based used for dipping, 8 hrs at 200 F ,

neighbors think i'm cookin crack at night,

wandering around the back yard with a flashlight at 2 am does not help,
View attachment 88573

No officer… I was just checking on the transformer potting. What else would I doing out here at 2 in the morning with a flashlight?

Get in the squad car buddy, you can explain it to the desk sergeant at the station