Anyone tried to fit an OEP (RS 210-6475) OP tx. to a DAC90A?

[Nickthedentist]

Hello everyone,

I grabbed an unloved and cheapish white DAC90A from the local "antiques" place yesterday for not very much.

The cabinet, grille and dial glass are nice, though the knobs have nibbles around the edge where some twit's been levering with a screwdriver.

Anyway, the OP transformer is o/c. I know I should send it to one of our experts for re-winding, but I have several new miniature output transformers in my spares store: https://uk.rs-online.com/web/p/audio...rmers/2106475/

Has anyone managed to shoehorn one of these in? They're fractionally bigger than the original, of course.

I wouldn't mind mounting it in an unconventional place, so long as it doesn't involve drilling the cabinet and is safe.

Any suggestions, chaps?

N.

[Ed_Dinning]

Hi Nick, it should work and has a suitable 2KV isolation, but frequency response may be effected. I'd be interested to know if it is noticeable.

Ed

[crackle]

Can you mount it on the speaker like in some other radios.

Mike

['LIVEWIRE?']

I have an OEP Transformer type B18A011F, wjhich is almost exactly the same size as the original, and will fit on the chassis. Not sure if RS list that one. I got mine from That's Audio in Kidlington, Oxon for £15.00

[McMurdo]

Yes, I've fitted one. It's fractionally bigger, frame-wise, than the original one. I cropped the two mounting ears on the new transformer slightly short (making the holes into slots) and then re-drilled the mounting hole nearest the front of the chassis, using the other one as-is.

PS, just uploaded a video to see what it sounds like

https://youtu.be/8jvOxhHKYOQ

[G6Tanuki]

Given that we're talking about an AM/MW receiver here - whose IF tuned-circuits should have at most a 10KHz bandpass for both AM sidebands - which means 5KHz after-detection, I don't think any replacement output-transformer is going to be taxed in regards of frequency-response.

"If it fits, and the impedance-ratios are right, go for it!"

[G8UWM-MildMartin]

The datasheet shows it as having the same dimensions as the Louth LT1360, which fits if the front hole in the chassis is re-drilled a bit nearer the edge. It overhangs slightly, but nowhere near enough to touch the loudspeaker.

[Ian - G4JQT]

I've fitted them in a couple of sets - DAC90A and A22. Maybe my it's imagination, but I got the impression the bass response wasn't as quite as good as the original transformers. Can't see why.

[radioman]

These transformers have interleaved 'E' and 'I' laminations -not stacked and with an insulating gap - so despite claiming 40mA d.c. rating I would think that they could start to suffer from core saturation problems which will not help their inductance and hence bass response.

Andy

[Ed_Dinning]

Yes, I hadn't spotted the non interleaved lams on the datasheet, so it should not really be sold as suitable for single ended use.
You could always dismantle and rebuild with about 2 thou of paper in the gap.

Ed

[Nickthedentist]

Originally Posted by 'LIVEWIRE?'

I have an OEP Transformer type B18A011F, wjhich is almost exactly the same size as the original, and will fit on the chassis. Not sure if RS list that one. I got mine from That's Audio in Kidlington, Oxon for £15.00

Thanks Mike.

That one looks a better option, doesn't it, folks? Specifically specified for use with a UL41: http://www.oep.co.uk/page-content/da...0issue%202.pdf

And OEP are literally a 15 min cycle ride from me. I wonder whether they'd supply direct?

Either way, I've decided to have the original re-wound, will PM you Ed

Thanks for everyone's useful input,

Nick.

[Ian - G4JQT]

Thank you for that link. Very interesting and I'll probably get a couple of those transformers.

[Sideband]

The only problem is....they don't show a picture of it on the website....does this mean they no longer stock it?

[Keith]

Available from their online shop - https://www.ebay.co.uk/sch/m.html?_s...A011F&_sacat=0

[Sideband]

All good then!

[Herald1360]

Page linked doesn't show any output transformer. neither does search of their online shop.....

[Station X]

http://www.oep.co.uk/products/audio/5

No picture, but if you click on the blank image it links to the data sheet.

I guess a phone call or email is needed to see it it's stocked.

[Ian - G4JQT]

Just received two lovely B18A011F transformers freshly made by OEP.co.uk for thatsaudio.co.uk after a friendly and helpful email exchange only two days ago!

I suggested that the may like to contact the BVWS and have an advert in the Bulletin showing their products and services. I forwarded the editor's details and they said they will make contact.

I got the impression they didn't know about the BWVS or the vintage forums which seems a bit odd as they describe that particular transformer as suitable for the UL41 - our kind of stuff. I always assumed that valve was for mainly domestic equipment, but maybe it is more widely used.

Anyway, this looks like a company that will have a few very useful items for us. I wish them luck.

Ian

[Nickthedentist]

Good work Ian. It's remarkable they sell any at all if there's no advertising with folks like us. Who else would want one?

I plan to ring them later to see if they'll supply over the counter in small quantities as I live only a couple of miles away.

N.

['LIVEWIRE?']

As I noted in post #4, I bought my B18A011F Transformer from That's Audio in Kidlington, but never thought to mention to them this and other Vintage Radio Forums, or the BVWS, so thanks, Ian, for so doing. I'd previously bought a rectifier valve from them. Their main thrust seems to be guitar & P.A. Amplifiers, but they're still the kind of company deserving support. Check out https://www.thatsaudio.co.uk/ for further information