[Amps] Microwave oven?

[Ian White, G3SEK]

Alek Petkovic wrote:
>You must also remove the two reluctance slugs that are wedged into the 
>core. Not sure what they do but you don't want them in there for your 
>ht supply.
>
In effect they make the transformer current-limiting, and indeed you 
don't want that. The slugs were force-fitted, so with a hammer and a big 
punch you can drive them out.

>A better option is to have 2 identical transformers and run the 
>primaries in parallel and the secondaries in series in a grounded 
>centre tapped configuration. This does away with the risk of the ht 
>flashover.
>
True, but it still leaves each transformer operating as a half-wave 
rectifier, with a net DC current flowing through the windings as well as 
the AC component. This takes the core much closer to saturation.

>There is another disadvantage with these transformers. The core 
>laminations are generally welded. I think that this results in 
>increased core losses and heating.
>
These transformers are designed "close to the edge" in every way, to 
keep the cost down - just compare the size and weight of them with the 
transformer you'd normally use in a PA that has the same power output as 
a microwave oven. They're undoubtedly better than no transformer at all, 
but not as good as the ones we normally use.


-- 
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
                            Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek