28 Feb
2007
28 Feb
'07
4:27 p.m.
On 28 Feb 2007 at 23:41, Tony Duell wrote:
Well, I like things to work, but equally, I do try to
maintain the
original design. For example I probably wouldn't replace valve rectifiers
with semiconductors.
Assuming that the load characteristcs allowed it, I'd do it in a
heartbeat, particulary with noisy gas rectifiers (such as OZ4).
There used to be a small market for direct plug-in solid state
replacements for the more common ones, such as 80, 5U4, 5Y3, 6Z4,
etc. But the old auto-radio vibrator supplies really improved with
decreased noise when one replaced the old cold-cathode gas rectifier.
The filament for a 5U4 is what, 5 volts at 3 amps? That's 15W of
heat that you don't have to worry about.
I'd also replace old selenium rectifiers with silicon diodes. Many
years ago, IR offered cross-referenced silicon replacements for
selenium rectifiers. Seleniums are pretty stinky when they went
kablooie.
As far as anode supplies for CRTs, go, you may want to consider
several junkbox solutions other than voltage multipliers. You can
cobble up a small inverter with not much more than a transistor or
two and a small transformer. There are also packaged versions of the
same that can be found by scavenging old photocopiers. You can also
find HV supplies in air filters, bug zappers and a whole host of
other things.
Cheers,
Chuck