W.E. 6L6 OPT

CJ · May 13, 2014

here we go again,

transformaholic relapse #19,

a perfectly good Western Electric 6L6-GC push pull that was functioning well in a DIY Ampeg Portaflex bass amp up until this point,

had to find out what made it sound so good,

a spiritual awakening of the coil/core variety,

sneaking into the pic is a guitar pick, made from a Wells Fargo debit card that is also no longer functioning,

CJ · May 13, 2014

cost of sawing the transformer: 1$

cost of knowing where to saw the transformer: $1,000 dollars
(a Steinmetz joke)

after the saw comes the heat gun, then the electric bill, ???

CJ · May 13, 2014

1945 black tar does not melt easily thanks to poly-chlorinated-biphenyls, (PCB's)

Dupont, better living thru Chemostry, which is what you need after smelling the vapors from the potting compound and dirty sock used as pot holder,

CJ · May 13, 2014

this is called lead flagging, a mundane but important part of transformer mutilation,

CJ · May 13, 2014

say hello to my little friend, the hack saw,

removal of black tar coated hardware is time consuming, so...

CJ · May 13, 2014

lead flags fall off sometimes, so we do a backup drawing,

CJ · May 13, 2014

luckily the coil was dipped by itself, so the lams fell right out after the keeper lams were removed,

rusty after 70 years of hibernation, wonder if that's why this thing sounds so mellow,

CJ · May 13, 2014

nice workmanship back then, clear insl with wire staples,

CJ · May 13, 2014

7 more wires under the outside wind which is a 60 ohm job for long distance speakers, maybe a PA on a battle ship as this is a Navy transformer,

CJ · May 13, 2014

some leads come from the left, some from the right, removing the lead plate and trying not to rip out wires, so we heat it up first,

coil is placed on the winding machine so we can use the turns counter when unwinding,

CJ · May 13, 2014

do not know the reason for splitting the insl into halves, maybe to allow impregnating fluid into the coil, maybe to give the coil shape, maybe to save money on insl,

CJ · May 13, 2014

layered paper coils require margins so that the wire does not fall off the edges during winding and to provide some distance to the core so the coil does not short out,

nylon bobbins allow more turns per layer, margins may or may not change the high frequency response of the coil as capacitance changes as turns per layer changes,

CJ · May 13, 2014

can this gap be a winding tweak to perhaps break up symmetry and thus change capacitance?

maybe,

this coil has a very flat response as you will see from the freq graph,

CJ · May 13, 2014

another gap on the opposite side, getting close to the inner wind which is a 600 ohm tapped job which can be used as a nice balanced direct out for a mixing board,

CJ · May 13, 2014

very heavy wire used on the 600 ohm wind, #28,
this puts the high turns pri right in the center of the coil. better response? better insulation from the high plate voltage to the core? maybe both,

CJ · May 13, 2014

finally down to the first start, lead 7, strong core tube, built with more paper than most coils,

CJ · May 13, 2014

this partial layer is to improve hi freq response,

these tweaks come from experimentation and will be kept secret by the company,
so you will not find any info on this in text books,

you want inner layers to be flat as they form the foundation for the rest of the coil,
so if you see a partial layer this deep into the coil, you know that it is for tuning purposes,

CJ · May 13, 2014

here is the print,

CJ · May 13, 2014

freq response>

CJ · May 13, 2014

pri inductance vs freq>

W.E. 6L6 OPT

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