How to measure step up transformer ratios

I own a vintage Tango Step Up Transformer that has a selector switch with settings labeled 3, 10, 20 and 40 ohms.  I've used it quite happily for years and have just relied on trials to match the settings with my cartridges.  But I'm now thinking of buying a Soundsmith Paua, which evidently sounds best at 1K+ loading.  

I would think my Tango's '40' setting might work . . . but before buying the cartridge it sure would be nice to know what the ratios of this mysterious but awesome SUT is ;-)

Is there an inexpensive tool I can buy to measure a step up's loading ratios?  Thanks for any insight you can share.  

PS -- I've often thought that I should have the Tango modified to bypass the selector switch . . . but it's beat all comers in it's present form, and they were mostly direct-wired single ratio designs.
You could do this with your PC if you were willing to hack a couple of those cables. :)

Get a signal generator (lots of free out there, including Room EQ Wizard).

Load the output with a typical resistor.

I'm not sure what the appropriate voltage range is, so you may need a multi-meter to calibrate the output first. You don't want to overload the transformer (if that's even possible).  Maybe 100mV is a good range?

Use the microphone inputs to measure the voltage at the in and out sides of the transformer.


Thanks Eric but all of that is out of my league for sure.  I grade pretty high on analog setup skills but when it comes to technical stuff like you've described it would take me a week to understand and execute haha
I did find some measurements of other SUT's on the Vinyl Engine's "Marriage of Step Ups and Cartridges" article.  There were two listed with four settings and both topped out at 470 ohms . . . I would think that's likely my unit's highest ratio as well.