[mcp6453[_2_]]

I read this information on http://www.lundahl.se/faq.html and thought it was
funny for a commercial site.

"One of the LL1674 seems to be off-spec, the secondary static resistance should
be about 605 ohm and 3 of the transformers do indeed measure 600-608 ohm. The
fourth one measures 560 and 600 ohm for the two secondary resistances, this
would lead to an off-balance surely? Gain matching and CMR would not be so good.
Difference in copper resistance is due to difference in wire gauge. It is
possible that we used wire from different runs or from different vendors.
However, the number of turns should be correct. (I say "should be" as ****** do
happens, even at Lundahls. But if the number of turns was not correct, the
difference in copper resistance should have been around 100 ohms for the LL1674
(representing two full layers).) "

[Scott Dorsey]

mcp6453 wrote:
I read this information on http://www.lundahl.se/faq.html and thought it was
funny for a commercial site.

"One of the LL1674 seems to be off-spec, the secondary static resistance should
be about 605 ohm and 3 of the transformers do indeed measure 600-608 ohm. The
fourth one measures 560 and 600 ohm for the two secondary resistances, this
would lead to an off-balance surely? Gain matching and CMR would not be so good.
Difference in copper resistance is due to difference in wire gauge. It is
possible that we used wire from different runs or from different vendors.
However, the number of turns should be correct. (I say "should be" as ****** do
happens, even at Lundahls. But if the number of turns was not correct, the
difference in copper resistance should have been around 100 ohms for the LL1674
(representing two full layers).) "

They are really cool people.

This sort of thing is what you get when you have companies actually run by
engineers, and driven by engineering requirements. People actually say
honest things about their products instead of listening to what the marketing
department wants them to say. And it's hard not to have a bit of a sense of
humor when you do such things.... witness the "Write Only Memory" and the
"Polish Operational Amplifier" datasheets that somehow made their way into
published data books.

If someone asked a major line transformer vendor about different value
resistances on coils, they would mostly have got a line of garbage about
how everything is fine. Lundahl is honest.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."