Wednesday, March 27, 2013


     I decided to clean the front panel and apply a little liquid furniture polish:
     This is an hour after dabbing on and dabbing up any excess.  The line between protected and exposed finish is a lot less obvious.


  1. That's coming along real nice. Less is better, you're right.

    Is it just me or is that old B+ test point hole a drill-wobble off center?

  2. Roberta X (at lunch)March 28, 2013 at 1:40 PM

    Both off-center and whatever the six-pointed version of trochoidal would be. I've seen uglier mods -- I "installed" (for want of a better word) a National AM dial on a Heathkit HW-16 with a worn dial disc, when I was in my very early 20s.

  3. Not all ugly mods are on the outside. I sold a HW-16 to one of my 'tronics teachers in college. He was a young guy right out of university himself, so he was sure he was an expert. Anyway, to cure the yoopiness of the 16's CW note he built a shunt voltage regulator for the oscillator stage out of a NE-2 bulb, thinking it would limit at about 90 volts. Poor guy didn't realize he'd built a relaxation oscillator to modulate his oscillator.

  4. Og, I was thinking of molybdenum disulfide -- but after reading the MSDS for it, I don't know why they made us get rid of it. Maybe the eyewash requirement.

    Dave, you can use neon lamps as a voltage reference -- it was a hot app in the 1930s -- but even a nice fat one won't handle enough current to make much of a regulator in and of itself. Which is why VR tubes are so very handy. The wickedest regulator trick I know is to use a Zener to lift the ground terminal of a 3-termnal regulatior (78XX, 79XX); this gets you up in VR-tube ranges with minimal parts count, though heat-sink insulation can make for extra work.