On 19 Dec 2003 06:56:18 -0800, Bruce Kizerian wrote:

Roy Lewallen wrote in message ..
People here have recently mentioned tubes intended for portable
operation, with plate voltages of around 20 volts. Much more common are
tubes intended for running from mains-powered supplies. These mostly
require plate voltages that can be lethal. You should consider this when
designing kits for kids.

Roy Lewallen, W7EL

apart from the 6.3v heated types for car radio most such typers were
manufactured before 1930 and somewhat hard to find today, still the
WWII type RE074d is very rare

That's is one of the reasons why a 9 volt battery is probably the
highest potential you will seen in my kits. The manuals I write are
full of precautions about soldering, erecting antennas, etc....but NO
high voltages...

But I still remember the jolt I got as a kid which caused me to drop a
heavy chassis on my toe...How did WE survive?

I connected two 90V batteries in series and wasn't aware that the
headphone wasn't particularly insulated., still remember it very well
over 40 years later...

G3RZP mention the use of 6J7 as detector in his HRO, see Radcom nr
1/2004 page 45. It is described as combined AM/SSB detector, but I
wonder what sort of detector it is for AM. Is it grid or anode
detector? It is shown on http://home.online.no/~la8ak/17r.htm
Suppose it is still low level IF for AM - as for SSB.

On http://home.online.no/~la8ak/17s.htm I've shown the application of
a triode-hexode ACH1 which may be somewhat similar to 6K8, but here
the control grid is biassed with -4V and obviously operates as a
completely different AM-detector.

73
Jan-Martin
LA8AK
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