How many lams for OPT?

[Landins]

Just gotta try this. M6 lams arrived the other day and copper is on the way. According to seller these lams are for 2 hs-52:s. What? Surplus deal unnoticed or is the core on the hs this wide? This is 140 lams 0,014 thick. Turns, windings and so forth are posted here on forum (i.e. Thank you CJ) but Im a little bit uncertain on amount of lams. Somewhere in the region of 40 seems resonably correct. Fair enough? Mxr for reference.

 

[joaquins]

I just put the last one with little force, not too much but not leaving anything loose.

I like your winding rig! etheory has something to do with it?

JS

 

[Landins]

Nope and thanks! Just grateful that my mother saved these childhood artifacts.

How many lams did you end up with in the end? I gotta figure out how big of a bobbin i gotta fold. Ill try to see if there is some perm specs and start in that end.

 

[mitsos]

says here 7/8" stack.  Also says 50/50 core though? That would be 50% nickel, if yours are M6 (steel) they won't work with the same turns. Well, it should "work" but it won't have nearly the same inductance, so bass may suffer, depending what it's used for. please take pics, interested to see the outcome.

 

[Landins]

:Ahhrrmm. Yes Im a bit ashamed over that . It took me a while to get the dimensions right. 7/8" is approx 22 mm so the stack is indeed for two opts. And thanks for the reminder of winding scheme. Ive soon read every post by CJ on this forum.

Inductance may be an issue. I went for sellers description that these are meant for the HS-52. If i get a lack of bass I may go down in wiresize and up the turns. Since it it is a parafeed output, dc is no problem. Got a bigbig 4uf russion PIO as output coupling.

Working on my second v76, found it hard to get hold of nice opts on the market; got :mad, built lego . Help me straighten this out. Parafeed output seems quite tolerant to opt primary z as long as anode of opt-tube is properly chokeloaded? I know CJ went for the Hs-52 on the v72 and jensen 15k for the v76. Original pri-z is somwhere around 80k in original.

Winding noob as me will go for trial and error by ear.

 

[MatthisD]

You should expect much lower inductance, too low for a 15K or 10K winding. I'm guessing the HS-52 primary measures 80H to 100H which isn't generous to start with and if then stacked with M6 it would be under 30H I'd imagine. If you then reduce the wire size to 0.07mm or smaller to allow for more turns it will be more difficult to hand wind with wire breaks more likely, also the DCR of the secondary will become quite high if you maintain the turns ratio. I don't mean to discourage you from winding this but it will be tough to get good results with M6.

 

[Landins]

Hmmmm this is bad news. And im all so exited about winding!! 

If I understood you gentlemen correctly the possibility of gaining high reactive values with the M6-core is slim. The M6 is perhaps aimed at transistorbased/DOA low impedance use?

Not by discouragement but, its a waste of time winding something that doesent have the right conditions. Any suggstions on use of these lams? I have: windingmachine, M6 lams, wire 0.10, 0.15, 0.25 mm in great lengths, patience, curiosity... I wants: plate chokes, output trafo high z - to line. And I dont like to have material lying around unused

 

[mitsos]

well, for comparison, those lams are slightly larger than a 1/2", which is what's used in the small API output, the 2623.  Those have 3 windings of 75 Ohms each, and are about 600 turns or so.  CJ's HS52 sheet above, calls for 2 windings of 255T to make up the secondary (with taps for the other ratios).  Anyway, so 500 turns on the HS52 core would give you about 600 Ohm impedance, whereas on the API, it's 75 Ohms.  The inductance needed for 75 Ohms is much less, and I'm guessing you'll get just slightly higher inductance on the secondary than a winding of an API2623.  So, based on that, pri inductance would be nowhere near what it ought to be, so my guess is it wouldn't work too well.

You can use these for a 600:600 line transformer, sort of like the HS56, although that also uses nickel, it will still work with steel. You could probably build a couple chokes as well, I've seen some about this size.  Edcor has some smaller trafos, maybe their site might give you some ideas.  For output trafos maybe go with something larger, or nickel or both.

 

[MatthisD]

I agree that a bobbin wound bifilar 1:1 or trifilar 1:1+1 output is the most logical use for these and to look at the Edcor transformers that use this Lam and Sowter's v76 interstage choke which is a similar size. All wound without insulation between the layers in order to maximise the number of turns that can wound in the available space. 0.1mm wire is too thick for a high impedance plate choke on this core. See the hammond 155C, my guess would be that it is wound with 0.09mm which may have enough turns that once the core is replaced it could be useful for something.
  If you want a dual chamber bobbin for a 15mm stack height and a chassis mounting bracket to fit this lam you can get a 6VA power transformer from Mouser, dump the core, cut the windings off the bobbin and then rewind it with very thin wire. I don't like the waste of materials that this creates but for a one-off DIY job it would save having to make or source those parts elsewhere.
  You could design your own low impedance choke for a Neve BA183 with 0.25mm wire. As it is so few turns you won't have wasted too much time if it is a failure.

I have 50/50 laminations of this size, some are new the others from old UTC and Jensens, so its not impossible to DIY the HS52. If you do want to wind one you'll need 0.09mm wire to get 2850 turns total otherwise if you were to use 0.1mm wire you'll have to add extra layers which will use up the winding space that the secondary should occupy. On top of that you have to consider the insulation material thickness and an enclosure to house it or another form of mounting the transformer.

 

[Landins]

Bought a house today and Im a father to be. That was easy. This is hard.

Thanks for suggestions and ideas. Just confusing about different information and I was awol on geology in school. CJ:s schem points at 50/50 but http://groupdiy.com/index.php?topic=35664.20 points at M6. Anyways the choke path is interesting. Problem with output choke on the V76 is that it must handle 12 ma of plate current so wire cant be too thin. I rewound the hammond 156c tightly and fitted 8500 turns of 0,1 in three chambers glued up on original bobbin. Dcr up to 1,6k (to low) and it doesent choke until 1,75khz.

Winding a choke on the m6 may be intersesting following the v72 disassembly here on forum. But to keep capacitence low a dual och tripple bobbin is the way to go. But fitting vs wire size is still an issue. The v72 choke is wound with #44 i belive, but then the ef804 only draws <1 ma.

Got some two kilos army supply pwrtrafos 230/6v 1940:s stuff with bobbin and all. They may do the trick.

 

[Landins]

Ignore info on rewound hammond. Miscalculated.

 

[Landins]

Ok. Patience lost and I went for a wind with what I have and wound according to HS-52 specs. Looks kinda good to me. Test conditions: 2v pp, 4uf, cap, 600ohms dummy load. 20hz:

 

[Landins]

2khz:

 

[Landins]

20khz, little bump:

 

[CJ]

looks ok,

if using regular lams as opposed to 50/50, just increase the stack,

maybe try 1.5 times the normal stack and see what happens,

you might have less inductance, but saturation level will go up from 12 k gauss to 18 k gauss with the steel lams,

this means you can increase the plate voltage on the output tube,

 

[Landins]

Yeah. Im quite pleased for a first wind.

I have more lams left than used in this first attempt so Ill build a paper bobbin that fits all of them and see how it looks. Core will be bigger.

For future project i located permalloy kits from the motherland Germany.

Drc readings are 540 ohm something on primaries (I upped the turns to 1500x2 just cause i had room and because its a nicer number), and only 10 ohms on secondareis as I used a bit thicker wire.

Final judgement will be i live situation with reactive load. Reactive dummy loads, anyone?

 

[Landins]

Did another one according to specs with more serious insulation and bigger core. This is what gives in Henries:

100hz - 60H
120hz - 56H
1Khz - 15,7H
10Khz - 1150mH

Impedance presented at 100 hz is, if my calculations are correct, around 41K.