[R-390] White lines on knobs and more

[Larry H]

Here's the update promised, and a pic is attached.  The knobs are done.
The white lines sure do go on a lot easier when the black paint is cured.
The wrinkling of the black paint was solved by using a good self etching
primer.  Thanks for the tip.

I've been busy on some other boring stuff, but the R-390A has been getting
a little attention.  The calibrator would not adjust to WWV, so determined
that the 200 kh crystal was oscillating a little too low.  Got a good one
so that is fixed.  That allowed me to adjust the EP on the VFO a little
easier, so it is now +/- 100 cycles.  As part of that procedure, I adjusted
the linearity stack so that it is much better than it was.  Before, it was
+/- 1.9 kh, now it is +/- 0.2 kh at the 100 kh points.  I don't know if I'm
going to try to improve that or not.  I also went through all the crystals
and installed about 8 different ones to get the band deviation down to
under 0.3 kh variance on the popular bands and under 0.7 kh on the rest.
In the process I took a few apart and cleaned them to get crystals that
were close enough to their correct frequency.  That was fun.  The power on
micro switch was not working intermittently.  Luckily, it only needed a
little adjustment on it's mounting bracket.  I did a quicky drift test, and
after it warms up for 20 minutes it's pretty good, + 300 cycles during warm
up.  After that, it's quite stable.  Right now, I think it is in good
enough condition to go through the alignment again and see what we get.
>From the use I've had of it up to now, the sensitivity seems good, although
I've not measured it.

Regards, Larry

On Fri, Aug 16, 2019 at 10:03 PM Larry H <larry41gm at gmail.com> wrote:

> Well, I finally got all of the knobs finished, except for one.  It's being
> a pain getting the black on it without wrinkles.  Tried a couple different
> metal primers to no avail, and they are supposed to be good for aluminum.
> Any suggestions?
>
> Here's a picture of my progress.
>
> I'm now working on the BFO stability.  It currently is drifting down about
> 150 cycles in about 1.5 hours.  This is fairly common for one of this age,
> but is not good for CW or SSB reception or some alignment procedures.  You
> can see my counter probe attached to the BFO output at the front left.  I'm
> going to try to get it down to less that 30 in .5 hour.
>
> Happy fixing.  Regards, Larry
>
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