Triad AO-3039T Output Transformer

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andYz00m

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Santa Cruz, CA, USA
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. :D
 
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dougsta

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Jan 1, 2022
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Edinburgh
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.
 

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CJ

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Jun 3, 2004
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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>

test.JPG
 
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dougsta

New Member
Joined
Jan 1, 2022
Messages
13
Location
Edinburgh
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

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Jun 3, 2004
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14,313
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California
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,
x1.JPG
 

CJ

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Jun 3, 2004
Messages
14,313
Location
California
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..

hi  v.JPG
 

CJ

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Jun 3, 2004
Messages
14,313
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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

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Joined
Apr 15, 2020
Messages
54
Location
Santa Cruz, CA, USA
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

IMG-0734.jpg
IMG-0735.jpg
 

Fdieck56

New Member
Joined
Dec 6, 2021
Messages
18
Location
Dallas
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
 

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