[Boatanchors] Hickok 600A

[Jacques Fortin]

Hello Walt,
When you mention that you have gone "solid state" is it just a pair of
silicon diodes you used to replace the 83 rectifier ?
A 83 drops a fairly constant 15 volt between each conducting plate and
filament.
To mimic a 83 behavior, you have to either add a 15V Zener in series with
each diode or use a single 15V (5W) Zener between the center tap of the 83
filament winding and the rest of the circuitry.
But the biggest problem is not there: it is related to the global power
transformer loading and the line voltage adjustment.
Replacing the 83 with solid-state devices only also remove a 15W load from
the transformer and this affect the calibration of the line adjustment.
You can then use 6 x 10 ohms, 5W resistors in parallel to mimic the 83
filament load (5V, 3A = 1.6666 ohms).
This way, all the global calibration of the tester will be preserved.
BTW, the 600A uses the same circuit and settings than the 533A.
On our side of the border, the Stark 9-66A and it's "upgrade", the Canadian
Marconi MU-101, also uses the same basic circuit with some minor changes.
Incidentally, the MU-101 is a "solid-state adaptation" of the 9-66A.

73, Jacques, VE2JFE in Montreal

The 83 rectifier in my 600A tube tester died today. Open filament. I went
solid state. It seems to be functioning properly when checking against my
other tester. But I would like to know what the voltages should be. I have
not been able to find any voltage charts on the web. Anybody out there have
one.
Walt Cates, WD0GOF
https://wd0gof.com/Hallicrafters