Gary Schafer wrote:


Try find a sub that is close to the design impedance of your desired
transformer.

-Chuck Harris

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While it is true that there is a limit as to how far you can "stretch"
the impedance of a mod transformer before getting into trouble, you
can go an amazingly long ways.

As an interesting example: The Stancor Poly-Pedance transformer that
has multiple taps to obtain various impedance ratios (15 to 120 watt
series) uses the same taps for 2000 ohms primary to 1150 ohms
secondary (1.74:1 ratio), as it does for 20000 ohms primary to 11500
ohms secondary. Also the same 1.74:1 ratio! That's a 10:1 range!

The link below has the ART 13 and other transformer info.

http://www.amwindow.org/tech/htm/modtran/modtran.htm

Select Miscellaneous to find the ART 13 transformer specs and
connections.

Other transformers (stancor etc.) are listed also.

73
Gary K4FMX

Hi Gary,

Yep, you can get away with alot if you start with a transformer
that is overdesigned. The Stancor Poly-Pedance transformer must
have an excessive amount of iron for the 20K range, and an adequate
amount for the 2K range.

Not always the case. One would tend to think that the ART-13's
tranny would be built to be on the light side, being as it was
made to fly in an airplane. But I don't remember them being all
that light.

-Chuck Harris