Anyone ID this Loptx ?

[Al (astral highway)]

On the can there’s a date , 14 Dec 1988? This is maybe an inventory date instead of a mfr date.

I haven’t seen one with this appearance before ...

There is an auxiliary transformer with the blue winding being an overwound primary: underneath is a ferrite core with enamelled wire as a secondary. I’m not sure what this served ?

Thanks folks

[Heatercathodeshort]

It's an Ekco T161. Two versions were produced as this is the first version with the U25 mounted externally in a cradle with isolated heater winding. The heater winding of the early versions broke down to the core. The original heater winding for the EHT rectifier was then used to drive the small isolation transformer with a heavily insulated heater winding.
Later versions employed the familiar arched Perspex transformer. John.

[Al (astral highway)]

Thank you , John! Brilliant help.

Can you signpost me go any relevant sets using it so I can see their line-output stage? And do you know the EHT voltage driven at the correct frequency?

Cheers

[Cobaltblue]

The Model John gave is of the EKCO TV T161 the LOP valve was I believe a 20P1 the tube was designed for 10KV so I guess its there or thereabouts

Cheers

Mike T

[Al (astral highway)]

Thanks , Mike.

[Al (astral highway)]

Originally Posted by Heatercathodeshort

It's an Ekco T161...

John, fascinating.

It has a very unusual appearance for a line output transformer, doesn’t it?

1) It’s in an alu can (presumably oil-filled instead of bitumen - it’s vey light );

2) there’s no obvious EHT-tolerant lead or colour indication. (I’m assuming the central lead is EHT?)

3) there are long, flexible tinned wires for the other lead-pits

Do you have any details of the pinouts? This one appears to be NOS.

Cheers

[Peter.N.]

Never seen one of those, well familiar with the clear plastic ones that fall in half though.

Peter

[Cobaltblue]

Snips from trader 1039

Cheers

Mike T

[turretslug]

It's difficult to be sure but is the date 1958, rather than 1988?- the third numeral appears to be flat-topped, suggestive of a '5'. That would seem more credible, I know some stuff used to get stocked for a surprisingly long time but keeping a spare for a 405-line only TV for some 35 years after model introduction and 4 years after the transmissions closed down seems excessive!

Is the parallelled V9a in post #8 snippet 2 one half of the dreaded U801?

[Heatercathodeshort]

The circuit shows the resistance readings of the transformer so it should be easy to sort out the connections. The circuit does not show the U25 heater isolation transformer but all replacement transformers were fitted with the 'cradle'. [Later receivers employed the 3 link chassis with the familiar arched bridge Perspex housing] Reading technical notes of the time shows that all the early transformers broke down! Must have been a nightmare for such a reputable firm such as Ekco.
Yes TS. two anodes of the four anode U801 were employed as the boost diode.
The U801 with it's 80V heater was just a valve too far. Regards, John.

[Al (astral highway)]

Mike, thanks for the snippet...

So is T2, with the line drawn to ‘b’, EHT?

[ms660]

Originally Posted by astral highway

Mike, thanks for the snippet...

So is T2, with the line drawn to ‘b’, EHT?

T2 is the circuit ref. for the transformer but yes the black circle in the center will be extra high voltage out (AC) to the EHT rectifier....Often referred to as "RF" by some folks in the servicing trade.

Lawrence.

[Al (astral highway)]

Thanks, John.

I’m reading the snippet on a mobile device as no computer at the moment, so I can’t see great detail.

Very detailed post, thanks!

[Heatercathodeshort]

Hello Al, What are your thoughts on using the transformer? It is versatile for narrow angle tubes and simple line output circuits but has it's limitations due to it's early birth of flyback EHT. The original circuit was for a self oscillating line output stage but was changed on the later chassis. J.