1966 Mag: Build NE-2 Neon Bulb Computer - scan available

[Chuck Guzis]

On 27 Jul 2007 at 23:29, Tony Duell wrote:

> From my days in repairing _old_ colour TVs, I seem to remember that the
> valve that gave off the most Xrays wasn't the HV rectifier (a GY501 in
> most UK sets) but the 'Shunt Stabiliser' (often a PD500). This was a
> big triode connected between the EHT line and chassis, and formed an
> adjustable load on the EHT supply. The idea was to keep the total load
> (and thus the EHT voltage) constant as the CRT beam current 
> changed.

I seem to recall the early color sets here had X-ray warning stickers 
on the HV regulator cage (and it was always a metal cage), but you 
rarely saw them on the monochrome sets.  6KB4 was the most common 
type--a large, octal-based unit with a peculiar cup-shaped grid more 
or less completely covering the cathode at the bottom of the tube and 
about a 3/8" air gap between that and the long tubular anode (like 
that on a 1B3, but much larger) connected to the top cap.  Rated for 
something like 20-30KV if memory serves and about 30W plate 
dissipation.

Cheers,
Chuck