Vacuum Tubes at The DHTS Store
One of the many rewarding aspects of selling to the large and diverse community that exists on eBay is that we get to know about what drives a hobbyist's passion. When we started selling vacuum tubes (or valves as they are also called), we were uncertain as to the size of the community that would be interested in buying them. We have come to see that the love of this beautiful technological wonder from the dawn of the electronics age is alive and well. Interest in vacuum tube technology is very diverse indeed; antique collectors and restorers, technology historians, shortwave/ham/amateur radio enthusiasts, vintage audio and audiophiles, musicians, even artists have visited our store.
We have collected some resources and information pertaining to this subject. New content is being added frequently, so please check back often.
How to Pack a Vacuum Tube to Survive the Postal System
The first time that someone holds a tube in their hand, they usually remark as to how beautiful and fragile it is. Tubes are very delicate, not only because most of them are made of glass (called the envelope), but because there is an elaborate structure within the envelope that is susceptible to damage from shock - especially the heater filament. For this reason, it is imperative that the potential for shock be minimized by the packaging.
Designing packaging to resist shock is easy - you just use a really large box, right? Well, the challenge is to minimize the size of the package to keep the postal rates as low as possible, while still maintaining a suitable resistance to shock and breakage by crushing force (as you would normally encounter in a typical trip through the postal system. Nobody expects a package of glass vacuum tubes to survive being run over by a fork-lift truck).
The following outlines the process that we follow when packing tubes:
- We carefully open the small card-stock box that the tube is stored in and remove the tube for testing (whenever possible we test all our tubes prior to listing them). We then insert a 1/2 inch cube of foam rubber, replace the tested tube, then insert another piece of foam rubber. This ensures that the tube top and bottom are held in place and will not slide around in the box after we close it.
- We cut a piece of heavy corrugated cardboard and "wrap" it around the boxes of tubes to ensure that they are held rigidly in place and that some extra cardboard wrap protrudes beyond the length of the tube boxes. This cardboard wrapping is taped closed to create a "box". Cardboard sides are cut in such a manner as to ensure that the corrugation provides vertical support then and inserted against the tube box ends. More tape is used to make a strong and rigid box that can withstand a moderate amount of force.
- A heavy paper envelope or bubble mailer is cut oversize and the box is inserted inside. This creates a paper "flange" all around the perimeter of the box that will absorb any horizontal shock.
- Shipping labels, Fragile markings, and of course, more tape. There you have an economical method of shipping tubes that has been proven successful. To date, we have not had any casualties (knock on wood).
- Other variations on the above scheme have some individual tubes being shipped in a cardboard "triangle" or tent shape, which is extremely strong.
Testing Your Tubes
At the time of this writing we are using a B&K Model 707 "Dyna-Jet" mutual conductance tester which allows us to check a majority of the tubes we acquire for sale. Some tubes that cannot be tested with this instrument are checked for filament continuity. We always indicate in the sale listing the test status (i.e. test or not tested) and the condition overall of the tube. Generally, we avoid using the phrases "NOS - New Old Stock" or "NIB - New in Box" since we never really know what the history of these tubes are. Having boxed tubes does not necessarily mean that they are NIB or NOS and visual inspection cannot guarantee the performance or condition of a tube.
Links of Interest
The National Valve Museum
Frank's Electron Tube Data Sheets
Vacuum Tubes / Valves at The DHTS Store
Visit The DHTS Store on Facebook