Drugstore Tube Testers

You used to find the old standup tube testers just about on every corner drug store or grocery store.
U-Test-Em and Seco come to mind as the most common ones in my area.

They were great to sell customers unneeded tubes. However the pilot light test and the vibrator test were pretty good and accurate.

For a while, you could find them for about $10-15.00 all over they they disappeared.

Many times they would show a good tube bad, as they were just a rot gut emission tester.
 Some "Less than ethical sellers" found out that there were calibration pots inside them that could be adjusted to show perfectly good tubes as "bad". Often a TV repair shop had a deal with a store to place the tester in there and keep it stocked, while the store got a percentage of the tubes sold monies. 

Some folks were very lazy on re-stocking them, and they lost money, and some didn't bother to stock common audio tubes like 6L6 or 6V6. The smart ones kept an assortment of pilot lights and vibrators in the storage compartment, along with 0Z4's  and common AA5 tubes.
 One drawback was that people often slipped their defective tubes into the boxes and they got put back in the storage tray. So the store got screwed and so did a customer who unknowingly bought a bad tube. (Servicemen who had few scruples would also do this with used tubes and put them in a TV and charge the customer for new ones. This also happened when the serviceman did a house call and just was a tube changer and was too lazy to put the good tubes back in the set.

 I have often bought caddies full of tubes and there was a high percentage of used ones in with the new ones. typically the used ones were bad. (Like the guy who assured me the cabinet of tubes I bought were "All tested and good". Maybe at time of mfgr....Out of over 100 tubes 1 tube tested good..a 6AL5. Grrrr..)
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