Holes in Plates

I'm not familiar with those particular tubes you mention, but beam power tube plates are often made of two different pieces that are attached to each other by bending tabs in piece "A" through slots in piece "B". I see this in several 807's and 6146's I have on my desk at the moment (they're usually RF tubes, not audio, but they are beam power tubes.)

These holes usually aren't in the parts getting the beam but are external. I mean, you cannot see the cathode through the holes, you just see out the glass on the other side.

If you look at the holes (look at both sides!) do you see any such attaching-two-parts tabs in your tubes?

Tim.

Sno-o-o-o-ort!

Perhaps the holes are to let AIR flow through ?:-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

I was just about to opine that myself. Seems logical that alignment could be heat-dependent.

...Jim Thompson

folks here who actually know the answer !

That's about the age I made the move ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

Hurricane lamps?

To reduce deformation due to heat?

... to reduce the cyclic stresses and metal fatigue caused by such inevitable deformation during uneven heating. A correctly placed perforation can greatly reduce the chance of metal cracking.

Presumably the ones without holes only use electrons.

The holes may help prevent the formation of hot spots - just a guess.

Wasn't thinking of that - perhaps to make the valve more linear by creating more paths for the current to avoid saturation effects.

But I moved from valves to transistors when I was 13 - there must be some older folks here who actually know the answer !

They may have been used for location purposes during the forming process. It's a precision form of construction.

Bwahahahaha!

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

Since we're all guessing, I'm going with thermal stress relief. :-)

Or, since the plates are made of a special alloy of mysterium and unobtanium, it's to save material to make more anodes with - maybe they use the little circles to make nuvistors!

Cheers! Rich

No, no, no! It's those little disks at the ends of the filament in that split-anode 5C39 or whatever it was! Yeah, that's it!

Cheers! Rich

For jigging in assembly ?

Graham

"Tim Shoppa"

The cathode is visible in each case.

........... Phil

To mash the potatoes.

Matt Roberds

Nah- it was discovered early on that the holes reduce secondary-emission and its noise effects- all of this is late 19th century stuff.

They're not called "holes" BTW- it is perforation.

Ah, I see. Keep the supports from sending back stuff that gets past the suppressor grid??

...Jim Thompson