Epiphone Guitar Amp Output Transformer

[CJ]

this thing sounds good and i don't know why, so we are about to find out what gives,

3.8K : 8 Ohms,  pair of 6L6 but we use EL34's,

 

[CJ]

sq wave response very good, unloaded>

 

[CJ]

unique freq response, flat from 10 to 60 K Hz, then at 120 K Hz, output level drops to about half and stays there with no peaks or valleys, never seen that before,

do not know who made this, no EIA code,    TF 502 0 and 5246540  stamped on bells,

getting our lead breakout>

 

[CJ]

had a mandrel for EI 125 sq stack so we are ready to roll,  or unroll,

 

[CJ]

tape job

 

[CJ]

1 9/16"  winding length, offset margins, looks like #31 AWG, nice and tight,

 

[CJ]

layered paper coil, probably about 0.0015"  , strictly eyeball, we will measure tomorrow,

 

[CJ]

did we really eyeball .0015" layer insl?  oh  heck no, we read it off the handy dandy RDH4 winding data tables in the back of the book,

 

[CJ]

couple layers of clear poly, then the secondary, no taps, just 8 ohms,  lack of taps usually makes for a better xfmr,

so structure is gonna be just    pri - sec -  pri  which is not too common for a power output,

looks like 16 gauge, strictly eyeball,

 

[CJ]

83 turns in three layers,    filament tape works well for lead anchors,  poly tape will stretch, glass cloth is also good as the adhesive tends to stick better after varnish dip, 

 

[CJ]

inner pri, start is red CT splice,  finish is brn    913 turns ea section so final turns count is 1826 : 83 which works out to 22:1  , Z ratio therefore turns squared = 484 : 1, times 8 ohms = 3872 : 8 ohm speak,

good varnish job, got all the way across the inner winds,

coil was blocked with a wood wedge, about 1/8" on one side and a sharp point on the other, so the coil sits a bit off camber,  the wedge makes the coil/core assy tight and prevents the core tube from collapse as there is a lot of incremental  pressure as the coil is wound,  ever wrap a bunch of string around your finger until it is ready to burst? imagine that with copper wire of many turns,

it is good to assemble right away, i remember coming into work and seeing winders pissed off because one of their core tubes had collapsed, which means a complete rewind and wasted copper,  a slipped ship date and a scornful supervisor which led to a fight in the parking lot,  ;D

 

[CJ]

important for NFB purposes; note that blu and brn are opposite typical Fender OPT>