1950s/60s Output transformer identification - UK Vintage Radio Repair and Restoration Discussion Forum

Megatron · 21st Feb 2020, 8:55 pm

Can anyone identify the output transformer on the top right of this chassis? i came across this for sale and it reminded me that....
I bought one similar on a scrap chassis years ago when NVCF was at NEC, then 2 years ago was fortuate enough to find another at NVCF so have a pair.
They both test identically for turns ratio.
I then saw one on an auction site with some instructions that the seller was going to scan for me but never did. it was described as a universal OP transformer and was I am sure either parmeko or partridge.

Theyre quite distinctive looking, have 4 secondary windings, push pull primary, with UL. , but also airgapped core and tappings that suggest for PP or SE use.

would be good to find a data sheet. or any information on manufacturer or specs. in paticular if they can be used single ended.

Megatron · 5th May 2020, 8:30 pm

Bumping. Someone must have seen one of these before.

Nickthedentist · 5th May 2020, 8:48 pm

Crop of original pic...

toshiba tony · 5th May 2020, 8:51 pm

That looks a right beast, I never got further than building a Mullard510 And revalving PA gear in the 80s, but how many stages has that one got. The rectifier and the output bottles are obvious but what was the valve line up in the earlier stages?

Megatron · 5th May 2020, 9:00 pm

I dont know anything about the amp in the picture, as I say it was for sale and I recognised the transformer as the same as my pair.

Looks like a stereo amp with mismatched output transformers? or may have been dual mono with one channel for top and one for bottom?
Tetrode output stage with Gas regulated screen supply?
maybe a leak copy?

what do we think the valve line up is? i thought 6F6 or 6V6 outputs 5u4 rectifier acouple of S130s in series for screen supply regulation at 260V
then maybe 3 double triodes, one shared between channels as first stage & phase splitter then one each for drivers for output stage.
cant think of a small ST shape double triode though? ECC32/35 maybe ?

21st Feb 2020, 8:55 pm	#1
Megatron Pentode Join Date: Mar 2019 Location: Monmouth, Monmouthshire, Wales, UK. Posts: 166	1950s/60s Output transformer identification Can anyone identify the output transformer on the top right of this chassis? i came across this for sale and it reminded me that.... I bought one similar on a scrap chassis years ago when NVCF was at NEC, then 2 years ago was fortuate enough to find another at NVCF so have a pair. They both test identically for turns ratio. I then saw one on an auction site with some instructions that the seller was going to scan for me but never did. it was described as a universal OP transformer and was I am sure either parmeko or partridge. Theyre quite distinctive looking, have 4 secondary windings, push pull primary, with UL. , but also airgapped core and tappings that suggest for PP or SE use. would be good to find a data sheet. or any information on manufacturer or specs. in paticular if they can be used single ended. Attached Thumbnails

5th May 2020, 8:30 pm	#2
Megatron Pentode Join Date: Mar 2019 Location: Monmouth, Monmouthshire, Wales, UK. Posts: 166	Re: 1950s/60s Output transformer identification Bumping. Someone must have seen one of these before.

5th May 2020, 8:48 pm	#3
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,864	Re: 1950s/60s Output transformer identification Crop of original pic... Attached Thumbnails

5th May 2020, 8:51 pm	#4
toshiba tony Heptode Join Date: May 2006 Location: Accrington, Lancashire, UK. Posts: 978	Re: 1950s/60s Output transformer identification That looks a right beast, I never got further than building a Mullard510 And revalving PA gear in the 80s, but how many stages has that one got. The rectifier and the output bottles are obvious but what was the valve line up in the earlier stages?

5th May 2020, 9:00 pm	#5
Megatron Pentode Join Date: Mar 2019 Location: Monmouth, Monmouthshire, Wales, UK. Posts: 166	Re: 1950s/60s Output transformer identification I dont know anything about the amp in the picture, as I say it was for sale and I recognised the transformer as the same as my pair. Looks like a stereo amp with mismatched output transformers? or may have been dual mono with one channel for top and one for bottom? Tetrode output stage with Gas regulated screen supply? maybe a leak copy? what do we think the valve line up is? i thought 6F6 or 6V6 outputs 5u4 rectifier acouple of S130s in series for screen supply regulation at 260V then maybe 3 double triodes, one shared between channels as first stage & phase splitter then one each for drivers for output stage. cant think of a small ST shape double triode though? ECC32/35 maybe ? Last edited by Megatron; 5th May 2020 at 9:07 pm.