Triad A-57-J Line to end of the Line

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CJ

Well-known member
GDIY Supporter
Joined
Jun 3, 2004
Messages
15,652
Location
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here we go again, feed the habit, i'm a monkey, i know.

always wanted a peek inside this seeming popular transformer, rotten leads so it was free,

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<Do you re-pave your driveway with all the tar you melt-out of cans...>

no, but a fight breaks out  every time i empty the garbage,  :D


here we go, same lams as the world famous HS-29>

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extra jimmies>

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what the heck, winding print with the big data missing?  ???

did somebody steal the micrometer?

ok, luckily DCR of wire is like quantum mechanics, it jumps in discrete intervals that make reverse engineering possible providing that we know two things:

1) length of the wind
2) measured DCR of the wind

this coil has a structure of pri-sec, which means that it will be easy to determine the MLT (mean length turn) of each wind, for which we also have the DCR,

so we have a 12 F lam with a 3/8" stack, a 12 F lam has a tongue  :-* of 11/32",

so the core tube is 0.34375" x 0.375",

McLyman has a formula for MLT shown in the pic below,

so we have a primary  MLT of 2.127" and a secondary MLT of 2.755",



 

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  • MLT.jpg
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so we have a primary  MLT of 2.127" and a secondary MLT of 2.755",

we know the turns of both the pri and sec, which is 750 T each,

so now we can get wire length - 750 * 2.127" = 1595.25" = 133 feet

and sec - 750 * 2.755" = 2066.25" = 172 feet

wire charts have DCR of the various gauges in ohms/1000 feet,

so we need to know what the DCR of our pri and sec winds would be if they were 1000 feet long,

1000 ft/133 feet = 7.519  and 1000 ft/172 feet = 5.814

so we multiply our DCR readings of the transformer by these factors to get our DCR/1000 feet equivalent, hopefully they should be the same as the wire for both pri and sec should be the same unless they tried to balance DCR by using 2 different gauges which is unlikely with a coil of this nature (cheap).

so 32 ohms and 44 ohms (pri and sec) = 32 x 7.519 = 240 Ohms/1000 ft and
44 x 5.814 = 255 ohms/ 1000 ft ,

MLT formulas are not exact nor does wire have the same DCR all the way through the spool, so we do not expect 1% tolerance from this method, but lets see if we can determine the wire gauge from the chart, hopefully there is enough distance between  DCR figures to make a good guess, also, older wire does not always match up with today's wire and wire charts,

looking at the chart we see that #34 has a DCR of 261 ohms/1000 ft, the next gauges up or down give 206 and 330, so it looks like we have a match,

so the Triad A-57-J has 750 T of #34 for both pri and sec,
 

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Hey CJ!

I know this is an old thread - but do you (or anyone else) know off hand what the core and windings were made of?

I'm doing some research on old Triads and trying to get a definitive answer as to what materials that were made of...

thanks so much for the good work!
Timothy



 

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