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Old 16th Mar 2020, 11:14 pm   #1
FERNSEH
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Default Another unknown line output transformer.

Found this line output transformer in a box of bits and pieces.
It's a flyback EHT transformer from the late Forties or very early fifties. Looking through the old Radio and Television servicing books the most likely set to have this transformer is the McMichael model 512.
If it's not the McMichael set it will certainly be from a receiver that doesn't use a damper diode.
Winding resistances are: primary 100 ohms, EHT 700 ohms, scan coil winding 2.2ohms.

DFWB.
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Old 17th Mar 2020, 10:56 am   #2
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Default Re: Anoher unknown line output transformer.

It's the MK 6 Bush TV22 David.
Very odd one. The problem is they were always buried in some sort of screening can and not a lot was showing to remember them by. It's certainly an early flyback by the look of it. John.
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Old 17th Mar 2020, 12:33 pm   #3
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Default Re: Another unknown line output transformer.

Hi John,
Mark 6 TV22? Never seen one of those.

DFWB.
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Old 17th Mar 2020, 6:13 pm   #4
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Default Re: Another unknown line output transformer.

It was an emergency replacement during the Suez crisis David around 1956. Any other interesting Lopt's? I have a few odd ones myself. John.
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Old 19th Mar 2020, 6:45 pm   #5
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Default Re: Another unknown line output transformer.

Here's another mystery transformer. Never ever seen one like this in more than fifty years of fixing TVs.

DFWB.
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Old 19th Mar 2020, 7:58 pm   #6
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Default Re: Another unknown line output transformer.

That looks very much like the one fitted in my KB EV30 fom 1949. two types were fitted. A conventional design and this very advanced assembly with the 'ring' Ferroxcube core. J.
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Old 23rd Mar 2020, 12:36 am   #7
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Default Re: Another unknown line output transformer.

David was generous enough to send this transformer to me, I want to try to graft it into my Cossor 916 which has been lying dormant for two years.

It certainly looks the part. The first thing I did was to apply a drop of glue to the former as it was free to move on the core and slowly fatiguing the delicate winding leadouts.

The EY51 is mounted on a piece of Perspex which forms one of the cheeks of the Tx. It had cracked popping out the ferrule that the anode wire passed through. Someone had dealt with this is an odd way,
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I recognize the metal cup as what cabinet makers used to hide the handle fixings inside cupboards and drawers. I even have a pack. It seems to be used as a corona cap (there's topical), but would you expect one?

Anyway I heated up a drawing pin and pushed it through the Perspex to make a secure anchorage for a working EY51.

Well I've put it off too long, time now to check for continuity, I left the overwind to last and it's open circuit.

However, careful examination shows some damage to the outer layers of the overwind at one point I can see it on one of Davids photos because I know where to look.
A little excavation with my trusty hat-pin uncovered two breaks, but none of the exposed ends showed continuity. in desperation I teased out and cut another half-dozen or so turns and was rewarded with an end that measured 443 ohms to the top of the primary.

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It seems to have a reasonable ring to it too.
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It looks like a porcupine with those cut turns, the wave winding and the tape holding it all in place is going to make it nigh on impossible for me to remove the redundant partial turns.

Will it work like that when delivering EHT?

I've got the regulation thirty miliamps DC flowing through it while I think what to do next.
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Old 26th Mar 2020, 6:55 pm   #8
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Default Re: Another unknown line output transformer.

Quote:
Originally Posted by rambo1152 View Post
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I recognize the metal cup as what cabinet makers used to hide the handle fixings inside cupboards and drawers.
I've seen those caps before but underneath furniture to act as feet. Tapped into the bottom of legs, or direct to the baseplate of things that sat on the floor. Remember particularly that a tuffet (another name for a pouffe in our house) had them in.
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Old 26th Mar 2020, 7:15 pm   #9
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Default Re: Another unknown line output transformer.

Also known as 'Domes of Silence'. [See EMI manuals] J.
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Old 28th Mar 2020, 12:02 pm   #10
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Default Re: Another unknown line output transformer.

Here's another line output transformer. The valve top cap connectors might be a clue to it's origins.

DFWB.
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Old 30th Mar 2020, 6:38 pm   #11
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Default Re: Another unknown line output transformer.

Wow! Where do yer find 'em David? I can't remember that one. John.
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