triode Philips TC2/250 SE amp?

[marconi118]

I am a lucky (maybe unlucky) owner of 2 triodes philips TC2/250
is- it possible to build an SE amp of decent quality with it?
I estimate plate impedance to 4KOhm

would try to use a microwave oven transformer as a platte transformer....
what working point would you advice? plate and grid voltage?
datasheet annexed

 

[Osvaldo de Banfield]

Microwave transformers lacks air gap. So the primary will be saturated by DC current and large distortion can occur.

 

[gupsta]

Perhaps you are very lucky as they might be rather valuable but also fragile and also impossible to replace. I bet they would sound wonderful.

If you haven't done so already , I'd suggest having them tested, then decide to either spend big on good iron, or sell them for maybe big $$$, or if they're duds then turn them into a piece of artwork or donate to a valve museum.

Being fragile and potenetially quite valuable I wouldn't risk damaging them doing it quick and cheap with a microwave transformer etc.

Slow warm up (constant current) on those fragile filaments is important!

If you decide to spend big and do it right. Monolith Magnetics may have some suitable transformers. But if they go ping and die, consider that you would have to rework the circuit for some other tube type assuming you don't have any spares.

 

[euro21]

is- it possible to build an SE amp of decent quality with it?

IMO not.
As you can see in the datasheet, with this tube C or B mode feasible.
The most linear A (practically zero bias, or A2) section is around 500mA...1A anode current, where overall dissipation is out of range.
On the other hand these tubes requiring even enormous grid current.

 

[Fuling]

I wouldn't start a project based on a rare and expensive tube that I only had one pair of, but: Unless this is one of those tubes that has to be run with the anode hot enough to auto-absorb gasses, perhaps it could be run at around 1/3 of its capacity and then replaced with 211s?

 

[toshiba_nz]

They look wonderful!
Talk to

Miles Prower​

to get the best info

 

[50AE]

You could probably use a microwave transformer's core, but it won't work as it is. There is a magnetic shunt and also split bobbin winding. You will have cut the welds, rewind the transformer with the necessary amount of interleaving, then reassemble it by also inserting and airgap.

 

[marconi118]

not necessarily a MOT transformer, if you can give me an advice on suitable output transformer that don't cost a fortune?
and yes if not armfull for the tube I could run it at 800v instead of the 2000v used for clas C operation

 

[Fuling]

https://shop.piemme-elektra.it/Categories/93/Products/8472

Probably about as cheap as it gets for a transformer in that size range.