>This is an epilog to the recent discussion of filament inrush current
>reduction by means of controlled flux leakage in the filament transformer. I
>attempted to show in my comments that this was a viable concept
>theoretically, and some simple circuit analysis verified that. I also
>expressed some doubt about the practical possibility of accomplishing this
>without going to a different (and more expensive) transformer design. In
>order to fully resolve it in my own mind, I have done some additional
>research on the subject, consisting mainly of speaking with several
>well-qualified transformer designers. They all concurred with my opinion
>that
>the desired result is NOT possible with a conventional transformer. In
>particular, the primary and secondary have to be physically separated by a
>certain space to achive the controlled leakage. None had ever seen a
>successful design based upon a single, overlapped bobbin.
>
>One of my 'experts' has considerable experience with the SB200/SB220 amps
>and
>he confirmed my judgement that it has a conventional filament/bias
>transformer. The only current limiting will be that normally due to circuit
>resistance, including the fuse and AC linecord!
** I measured the filament inrush current on a SB-220 at 60% of what
Eimac recommends as max. (29A) The SB-220 uses a current-limiting type
filament transformer.
>
>> ...
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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