12-09-2021, 04:47 PM
I don't think I can do much about the electromagnetic pulse as I haven't even got lots of Farads and a big coil let alone a good stock of Uranium although the distances do make a difference so a tiny discharge right alongside would be just as effective as a large one out in the garden.
With regard to the variation in parameters within each type though I may be able to get somewhere. Some time ago I constructed a test unit for my valve test gear which uses an IC zero insertion force socket purely for subminiature wire ended valves. Using that it is easy for me to exchange valves without any soldering in a test circuit. It may be useful to put together a basic amplifier and subsitute valves, tabling readings of anode and screen voltages / current, gain etc. The only bugbear is obviously the running in time. I have come across this with all non recently used valves but maybe it has greater effect with rod pentodes? For DC work settling times of hours are often quoted which will be impractical and not really needed for our purposes unless someone is attempting an electrometer or analogue computer. Perhaps to try a couple first and see how readings change. My heater supplies are always regulated DC and if I remember correctly I have made a special regulator for these valves for my valve tester (which is home made and more attuned to switched point curve tracing than go / no go). Testing would really be a bit limited as all of a type would be from one batch (as bought) rather than randomly selected from different makers etc but would likely give some idea.
If anyone has any suggestion before I start please let me know (as well as letting me know if this is a poor idea). I may not test all but I do have 1j17b, 1j24b, 1p24b, 1j29b, and 1j37b types.
Tracy
With regard to the variation in parameters within each type though I may be able to get somewhere. Some time ago I constructed a test unit for my valve test gear which uses an IC zero insertion force socket purely for subminiature wire ended valves. Using that it is easy for me to exchange valves without any soldering in a test circuit. It may be useful to put together a basic amplifier and subsitute valves, tabling readings of anode and screen voltages / current, gain etc. The only bugbear is obviously the running in time. I have come across this with all non recently used valves but maybe it has greater effect with rod pentodes? For DC work settling times of hours are often quoted which will be impractical and not really needed for our purposes unless someone is attempting an electrometer or analogue computer. Perhaps to try a couple first and see how readings change. My heater supplies are always regulated DC and if I remember correctly I have made a special regulator for these valves for my valve tester (which is home made and more attuned to switched point curve tracing than go / no go). Testing would really be a bit limited as all of a type would be from one batch (as bought) rather than randomly selected from different makers etc but would likely give some idea.
If anyone has any suggestion before I start please let me know (as well as letting me know if this is a poor idea). I may not test all but I do have 1j17b, 1j24b, 1p24b, 1j29b, and 1j37b types.
Tracy
