Cordell low distortion oscillator for DA4084

[scopeboy]

Hi all

I recently got a Tektronix DA4084 distortion analyzer. The DA4084 has no oscillator, and I couldn't get the recommended SG505 oscillator at a reasonable price. So, I built my own. It is more or less a straight clone of the oscillator section of Bob Cordell's DIY THD analyzer, published in Audio magazine.

Read about it here- scopeblog distortion


One interesting thing that I found out: The DA4084 consists of an AA501 distortion analyzer plugin (minus the IMD board) in what the manual calls a "dedicated power supply", warning that it's incompatible with TM500 or TM5000 series plugins. Tek aren't kidding: the housing looks like a 3-slot TM5000 series mainframe, but it has the power transformer from a 1-slot mainframe inside. The SG505 may not have worked, even if I had soldered in the missing edge connector.

Happily the transformer had two unused 25VAC windings, and I designed my oscillator to run off these.

[cliffyk]

Nicely done!

I have a DA4084 as well, using a Kikusui ORC-11 low distortion (< 0.002%) generator as my signal source, however having it all in one cabinet would be neat...