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Re: Question on 'source impedance'.

Posted by Jim Doyle (A) on October 23, 2002 at 22:33:15

In Reply to: Question on 'source impedance'. posted by Story on October 23, 2002 at 13:41:28:

It's very confusing. My interpretation of the specs is that the
value == Zin Primary when the secondary windings are left unloaded.

As an example, the LL1660/10mA in Alt S (1:1.125 SE-SE) has a
Zin of 14k. This would compel me to use a tube that has an Rp
less than this value. I'd use a tube with Rp = 1/2Zin or 1/3Zin.
In other words, something like a 8532W with Rp=4400 ohms or paralleled 6N1P sections.

If you use the LL1660/10mA in other modes - i.e. 1:2.225. Zin=3.5K.
In this case, I'd be tempted to use a 5842 tube with Rp=1100 or
a 6C45 with an Rp of 900 ohms.

If you load the primaries (i.e. class A2), you need to account
for the load impedance reflected back into the primary.

I'm waiting to pickup a real oscilloscope (not my sound card scope)
and a function generator - so I can actually see what I am doing.

Edits: 11/02/20 11/02/20 11/02/20 11/02/20 11/03/20 11/03/20 11/03/20 11/03/20

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