Old transformers?inductor to identify please if poss....

[gary o]

Anyone know anything about these or the quality of them & what I could use them for in DIY ?
Heres pic



Well they came from unidentified apart from the make EMI tape
recorders....see this thread ...sorry pics are extra large tho...

http://www.groupdiy.com/index.php?topic=26678

Questions ..

would this quality be any good, I think these recorders they came from were semi domestic

Are the trans made by EMI...or who

the round thing in the centre has 1 coil on it is hand written type 728 ? IS this an inductor?
DC resistance with my cheap digital multimeter of 20.3 Ohms ...again any use for DIY ?

The one on left in centre has 944 stamped on it the one below it has a***rans is that altrans ? type 208 .... that one came out of a 1940s wave meter..any any use for DIY?
these two look very similar maybe both made by altrans ?

The top & bottom centre two on there sides top has 92925D on it bottom has 913 on it..they were from the EMI tapes mic inputs I think..again is quality any good ?

Finally the big one its quite a lump has A4 plus another unreadable stamp on the top on the other side on the coil covering is stamped 1428* cant read last digit..it has 600 Ohm output with centre tap that went straight to U pad on top 3X150 Ohm res then to 600 Ohm OP socket theres also 2 terminals marked 0 & 15...could that be 15 ohms output for speaker ?
it measures 3.9 Ohms DC with my meter & 600 Ohms measures 22 Ohms DC. I fed it output from my redd DIY & got decent sound from 600R output..
wondering if it would take HT thru its primary ? for my other BA type pres, how do I find that out without cooking it? if I cant obtain info on it

Maybe its old junk but thanks for looking

 

[rafafredd]

I do have some of these (I think two of them are type 208 also), and they test really well for level vs frequency response. Is it really 40s? Tests like 60s iron... I´ll check the exact number of mine. I have two models of transformers and an inductor, that looks like a high H plate inductor.

 

[gary o]

Hiya rafa the 208 thing came from a army wave meter thing il check the details of that machine but think it was 1947...Could that inductor be ok fo r V72 then ?
the big output transformer seems to work well as redd OP tran gotta do some more listening tests tho.

Thanks

 

[rodabod]

I've asked about the 208 one here before too. I belive Rob Flinn gave me some info. on it.

 

[MartyMart]

I have a a pair exactly like the one with 913 written on it, four leads on the
bottom.
One says 913 and the other 965/997 !
They came from a valve mic-pre from the 60's could have been an EMI ?
Have not tested them out yet, they were a gift.
MM.

 

[gary o]

Cool thanks for yr thoughts guys...cant find that thread roda ...I just took out the inductor from the other tape rec it has type 727 on it DC res of 107 Ohms

 

[rafafredd]

with that DC resistance you obviously won´t get even close to the inductance needed in a V72... If I recall, it´s 12k and 800H (or more???)... 107ohms probably gives you 5-10H typically. You could use it with a 5687, both sections in parallel for a really low impedance drive, and it sounds great. Get an H meter or use a vac mA meter to get an impedance guess on inductors and transformers... A sig gen, a pot and your scope also does the trick in a nice way for transformers.

 

[gary o]

Yeah went and dug out my V72 schematic of as u say its way out ...
5687 Tube is that ??

Thanks.

 

[Rob Flinn]

[quote author="rodabod"]I've asked about the 208 one here before too. I belive Rob Flinn gave me some info. on it.[/quote]

I did ????? Are you sure ?

I think I have some of these transformers somewhere, & was led to believe that they were from the BBC by the doner. Over to you Roddy !

 

[gary o]

Mine came from my old EMI tape recorders..I have TV program about BBC Radiophonic workshop (fascinating progam) in the prog theres 2 tape recorders that look alot like mine... Im not saying they are my two but similar models at least must be EMIs.