[R-390] OT: Problem with HP-606A linearity

[2002tii]

Barry wrote:

>Someone suggested that reorienting the dial in relation to the tuning cap is
>the correct way to do this.  I was skeptical since I thought that changing
>the endpoint frequencies was equivalent to "slipping the dial"; however, I
>gave it a try.  I was pleasantly surprised to find this had a very signicant
>effect on the linearity.  The first test got me very close and the second
>attemp (moving the dial a little more in the same direction) got me pretty
>much within spec.  Worst case is 1.1% (spec is +/- 1%).
>
>I created an Excel spreadsheet with some charts that show the baseline
>deltas (the "before" condition), the changes after straightening one set of
>fins, then the other set of fins, and finally the curve after moving the
>dial.  Pretty interesting.  I think if I move the "center" point (the
>linearity goes a bit negative and then a little bit positive), I think I can
>get the entire dial within 1%.

That was me -- glad it helped!  You can probably get the "saddle" in 
the error curve out if you fiddle some more -- it all depends on how 
much time you're willing to spend on it.

Best regards,

Don