W.E 618 B Transformer

  Western Electric mic input transformer  618-B

that lam is no longer available,  doc hoyer bobbin winds this with a 38 EI lam.

disclaimer: ***this data is from a phone conversation, not an actual dissection***

now we're talkin.  I'll dig around.  I have several sets of Z measurements from auction images.  Gee, these things were only $600 apiece 10 years ago.....

emrr said:

now we're talkin.  I'll dig around.  I have several sets of Z measurements from auction images.  Gee, these things were only $600 apiece 10 years ago.....

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This one seems a little more in line.

http://cgi.ebay.com/-Western-Electric-618B-input-transformer-tube-preamp_W0QQitemZ260482825456QQcmdZViewItemQQimsxZ20090927?IMSfp=TL090927146003r6386

Here's a pair for only 8K, with a no return policy.  :

http://cgi.ebay.com/2-X-Vintage-Western-Electric-618B-Input-Transformer_W0QQitemZ300346912074QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item45ee122d4a&_trksid=p3286.c0.m14


For a MC stepup transformer, this is gotta be the ultimate overkill.  ;D

Mark

anyone with a bad attitude about audiophiles is banned from this thread; you'll have nothing to add here.  ;D

This thread is about dissecting class distinctions in a read-between-the-lines manner.  No direct commentary!  Stick to the tech at hand.  Thank you, please drive through! 

Besides, after you've bought a Pultec and a Fairchild 670, you need something to lust after. 

Be warned, as with anything this expensive, there are fakes out there.  Fakes that would fool an experienced WE dealer at a long glance. 

The official reference data says it has a mag shield, but no reference to an electrostatic shield.
30/250/600 : 25K
total DCR 214:2680
average of 19 HY inductance on low winding
30-15K rated response

I have seen DCR measurements of 9.9/213/(222 total) : 1145/1642/(2k78 total) for the windings. 
Also seen 9.6/202/(212 total) : 1100/1530/(2k63 total)

There is a secondary center tap that I only see used in one amp for PP operation.  All other examples use the full winding SE.

I've heard from some old timers who worked at the WE plant here that it was an extremely difficult wind, by all accounts. 

emrr said:

This thread is about dissecting class distinctions in a read-between-the-lines manner.  No direct commentary!  

Click to expand...

Previous post edited for between-the-lines-courtesy.  8)

CJ said:

great!  how did you get those numbers?

the impedance ratio matches the turns, but only if you figure the pri used in parallel,

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The taps aren't brought out as separate sets; so you can't parallel anything.  Numbers came from official WE data and from several ebay examples listing measured Z's. 

CJ said:

splicing #48 is a bi-atch!

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... let alone winding it  ...



unless you have tensioners like this:





Even with CNC machine I'd still cut a special precision low friction roller guide.

Best, M

looks very pretty.  Is she free on Saturday?  More coffee needed, and I'll revisit. 

why would you want to go out with a wire tensioner?
you want to Relieve tension, not create it, 

i had the peerless k 241 d winding info a lil too close to the 618 b info, you know the rest of story, sorry!

i wonder howe many bots picked up that bad drawing  :

here is the orig diag:



anybody know the ratio on the 197a?

something to 600?

CJ said:

anybody know the ratio on the 197a?

Click to expand...

24K/6K:600

i think the pri is bi fi on this, makes more sense,

but the turns are right and everything else,

this would also make sense to the MC guys, they would have a nice, balanced low r pri for their cart,

and also, the engineer from peerless was known to "borrow" from the western electric winding data,

so this transformer is actually, by dumb luck, a lot like the first drawing i had up, which is the k-241-d,

that peerless is probably  #2 when it comes to mc xfmf favorites,


i have the lam i believe for the 197a, a lot like a 112 EI,  1  & 1 /8 th tongue,  9 / 16 " legs,

1 inch stack, = 1.12 sq inch cross section, beefey,

weird pri winding, might be bi fi as well,

here is a pic of the we 618b:



and the preamp:


no bi fi winding on this thing, you just flag the end of pri 1, then wind the rest of the coils,

and when you finish the last sec, yo start another 125 turn winding, and splice it to the first winding,

huh?

CJ, did you ever make one of these?

not yet,

the lamination is no longer produced, so it chilled me out,

Bummer.

  For WE 618 info :



For WE 618-C  DC resistance value :

Red/white stripe to Black  785 ohms
Red/white stripe to Red      209 ohms
Black to Red                        994 ohms

Black/white stripe to Blue      1738 ohms
Green/white stripe to Blue      1777 ohms

thanks or the cool data sheet!

going to try and find a core that has about the same inductance,

Is this transformer used for this? I'm interested in building one after I solve my being an idiot problem on my RCA BA-2