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

[Barry]

> 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

Yes, it was you and a fellow from another list who used to work at HP and 
seemed to know this was the right way to go.

Yes, I do plan to try to at least move the "saddle point" (the plot looks 
kind of like a sine wave) in an attempt to at least get the dial within 
spec.  If there are other things I can do to reduce the errors, I'd be 
interested in knowing what they are (I hope it doesn't involve rebending 
those fins, though).

One thing that I was curious about is a 2pF cap across both tuning caps (it 
is a push-pull oscillator).  I wonder what it's purpose is and whether it 
might warrant replacing (I have a dipped silver mica for it but didn't put 
it in place as I didn't want to replace what appears to be a factory part if 
it isn't bad).

Thanks!
Barry - N4BUQ