is it possible to wind your own F40 t-12 tulamp preheat ballasts

if it is how would you do it

I come from 240V place, here it would be a breeze, just winding a choke - 2 lamp fixtures just use 2 separate chokes

This is abulky but workable option since nothing prevents you from embedding a 120/240V voltage converter (autotransformer) in the fixture to power it with 240V

IIRC Eltam Mini 40N ballast (4ft 40W T12/36W T8 on 240V 50Hz, can be used with FS-U or FS-4 starter) is 0.87H inductance and few tens ohm wire resistance, but i can be wrong



As for "real" 120V Preheat ballast, there is needed a core with shunts as the same core is acting as the voltage converter and as the ballast itself. I am thinking whether a microwave transformer can be rewound for this purpose but i am unsure, and i dont know how to find out the magnetic shunt required

here the Universal 2 lamp F40 preheat ballast and it High power factor. If i were you I would submit a best offer
 http://www.ebay.com/itm/New-MagneTek-205-TC-P-Universal-Ballast-for-two-F40WT12-Lamps-Transformer-/310417749031?pt=LH_DefaultDomain_0&hash=item484656f427

@funkybulb that is too expensive for two of those
@ash winding separate chokes and 120 to 216v autotransfomer and then putting them all in 1 case is possible

Winding would be easy, finding the parts to make a transformer that is "ballast size and shape" might be more difficult. What kind of core would one use to wind a choke?

Pretty much anything given that it is big enough to not saturate

Modern fluorescent chokes are wound on steel EI (a type of core where the steel plates are in the shape of E and I, same as most transformers), but there are others as well - some old chokes i have are wound on a stack of metal plates in open magnetic circuit (magnetic flux travels part of its way in air) and padded with some more plates from the sides

The Eltam Mini 40N (240V 50Hz 36W T8/40W T12 choke) is wound on something with cross section about 800 mm^2 and IIRC its induction is like 0.87 H, wire resistance few tens ohm (the Mini 40N is known to overheat, so  so better to use a bit larger core about 1000mm^2)