The correct internal-inductance of Windfeld cart.?

Dear Axelwahl: I don't know to what brochure you are reffering but here you can read that >10 ohms:
http://www.ortofon.com/index.php?option=com_content&view=article&id=230&Itemid=225

I don't know too why is so important to you the internal-inductance but you can ask directly to Ortofon here:
http://www.ortofon.com/index.php

Regards and enjoy the music.
Raul.

According to the Ortofon specification sheet, the PW has an internal resistance of 4 ohms, and an output of .3mV. If you are trying to work out what kind of step up transformer will work for this cartridge, those numbers are what you need. These are pretty much normal numbers for a relatively low output cartridge.

As for the inductance, I have no idea. Why would you need to know the inductance? I would assume that the PW is like any other MC cartridge, which means an insensitivity to capacitance loading.

Thanks for the help, why I asked for the correct impedance?
To determine the bandwidth of my system after SUT loading!
f/3dB = R / 2pi*L ...that's why :-)

Got it right now by primary loading 13ohm! Fidelity Research XF-1 type M (1:31.6 ratio) ergo 47ohm natural impedance with 47k phono-pre input impedance. (47k/31.6^2 = 47ohm)

So, 13*47/(13+47) = 10.18 ohm primary input impedance to match PW >10ohm recommended impedance.

The brochure I was referring to is the very one THAT CAME WITH THE CART! Mr. Rauliruegas
(Ortofon do know about their miss-prints, why ask?)

Meanwhile NOBODY at Ortofon commits to a correct impedance figure, other then 10 - 100uH -- Not so professional I say --- the reason? "We don't measure it..." well, well, well

Axelwahl, You originally asked about inductance, not impedance. This naturally led some people to ask why you wanted that information, since the proper loading of your cartridge is easiest to calculate based on the square of its turns ratio of the SUT you are using, if you know the desired load. For example, if you want the cartridge to "see" a 100-ohm load (a reasonable guess for a cartidge with a 4-ohm internal impedance, altho I know the Ortofon likes to see a higher value), and if your SUT has a turns ratio of 10:1, then the proper value of the load resistor on the secondary side of the SUT is 10,000 ohms. (The square of the turns ratio = 10^2 = 100; 100*100 ohms (the desired load) = 10,000 ohms.) If you want the Ortofon to see 500 ohms, then you need a 50K ohm load resistor. Maybe you know all this, but the fact remains that inductance of the cartridge is not needed to make this calculation. Folks were trying to help you.

Hi Lewm,
thanks for sharing the calculations.
1) Fidelity Research XF-1 type M, is 1:31.6 xfactor i.e. 30dB.
2) That Windfeld is a bit 'funny' since with no SUT it seems to like at least 500 to 1k ohm load and with some phono-pre's it's even better with 47k!
(I and also some reviewers came to this same finding)
3) I use PRIMARY loading, because if you get it right, it sounds more open --- using secondary loading is something else since as you pointed out the || of your sec. load with the 47k pre-input imp / by the square of (in this case) 31.6 is what the cart sees. Therefore with NO sec. loading the cart sees 47k / 31.6^2 = 47 ohm, didn't I go into that alread?
So any sec. loading now goes || with that 47ohm 'natural-impedance'(I'm neglecting the primary DCR (in the XF-1 case only 1.2 ohms which is also part of the deal)
PRIMARY loading with 100 ohm makes (in this case) the PW cart go beserk, higher like 250, 500, etc is also unworkable.
So you check the minimum spec. loading (usually 2.5 x DCR = 4ohm DCR x 2.5 = 10ohm, it happens to be min. spec by Ortofon, right)
What's left is to get a 1:1 impedance match to this! i.e. 47x13/(47+13)=10.18ohm ---- and as it turns out this sounds the best of the 1001 different versions I've tested.
So it seems to me, that you are working with loading that is non SUT relevant --- the big difference is that with an impedance matched SUT, that cart is working in 'current mode' (not 'voltage mode' as in a non-SUT set-up) and THAT changes EVERYTHING as I had to learn. You can not, I repeat NOT, compare 'current mode' to the 'normal'-voltage mode- loading i.e. with out SUT. Even when using secondary loading -current mode rules?- apply, just that we are now looking at ~ 18k ohm on the seconary producing [47k*18k / (47k+18k)]/ 31.6^2 = 14.1 ohm what the cart sees. Going down to e.g. 13k to make the cart see ~ 10ohm makes it to bright and brittle --- so not all things are quite equal between primary and secondary SUT loading either.
Also using secondary 18k ALSO damps the secondary SUT side --- not necessarily what is best, depending on the circumstances.
I actually just wanted to figure out what bandwidth I can expect by asking an apparently simple question about INDUCTANCE of the PW cart (not impedance as you rightly pointed out, I can measure DCR, but NOT uH!) So... I am still guessing we are looking at ~ 10uH and that gives me ~ 23kHz bandwidth.
Thank you for careing,
Axel