MORNING STAR OBSERVATORY
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Drug Store Tube Tester

If you're old enough you might remember seeing one of these in a drug store, grocery store or even Radio Shack. You could pull all the tubes from your radio or TV, put them in a paper bag, and take them down to your local store to test. And hopefully you wrote down which one came out of which socket. Once you found the bad tube or tubes, the store proprietor would unlock the bottom and find new replacement tubes. And the price list is taped right inside the door.

Picture
This tester did not have a manufacturer's label anywhere that I could find, so at first I wasn't sure what company made it. It says Sylvania on the plastic face and inside the meter, but the meter label is just a cut out, paste on label, and the plastic face just slips in a slot and could be changed to anything you want in a matter of seconds. However, I recently stumbled across one of these testers that is identical to mine except for the Sylvania labels. It turns out that this is a U-Test-M brand and someone put a Sylvania sticker right over the U-Test-M name in the meter.

Picture
All the electronics are on the tube socket plate, so the rest of the cabinet top is pretty empty except for the AC wiring and flourescent light. And the tube chart.

Picture
The lower section contains the tube drawers and price list.

Picture
The back of the tube socket plate. The's a power transformer, a lot of wiring to the sockets, some range and current limiting resistors, and a small PCB.

I found two 100Ω 2-watt power resistors out of tolerance and replaced them. All the resistors on the selector switches are still OK.

The connector plugs for the tube socket wiring had some corrosion, as did the switch contacts, so they were all cleaned with contact cleaner and Deoxit.

Picture
The PCB has three transistors, and on the backside are half-a-dozen trim pots. No labels or instructions anywhere on what the trimmers do. The only component replaced on this board was the electrolytic capacitor.

Picture
This is an emission type tester but it actually does a pretty good job. If a tube reads good and has no shorts I usually go with it. If a tube reads bad or shorted I won't toss it without pulling out one of my other testers, like the TV-3 or Precision 10-12, to double check it. But the drugstore tester is usually right. The only time I've ever had an issue was with power tubes, which I think was caused by corroded pins on the interconnect cables, and was fixed when I restored it. Now it works great and I find it quite handy to have sitting there ready to go at the flip of a switch. And it just looks cool.

Page created 3/29/2021
Last edited 4/10/2021
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  • Home
    • About
    • Contact
  • Astrophotography
  • The Observatory
    • The New Observatory
    • - About the ExploraDome
    • - About the Lancaster Dome
    • - Building the Lancaster Dome
  • Equipment
    • CCD Cameras >
      • Orion Starshoot Pro
    • Mounts >
      • Orion HDX110 (EQ-8)
    • Telescopes >
      • Astro-Tech AT6RC
      • Celestron C-11 XLT
      • Zhumell 152mm Refractor
  • Projects
    • C11 XLT Mods
    • Orion SSPRO Camera >
      • Disassembled Views
      • Noise Reduction Mod
      • Temp Controller Mod
    • Ultima 8 Mods
    • Zhumell Refractor Mods
  • Non-Astronomy
    • Amateur Radio >
      • Boat Anchor Radios >
        • BC-348N Receiver
        • Collins 51J4 HF Receiver
        • R-392 HF Receiver
      • DIY >
        • Station Boom Microphone
      • Ameco >
        • Ameco AC-1
        • Ameco OCM
        • Ameco PT-2
        • Ameco R5A
      • Heathkit >
        • Heathkit SB-102 Station
      • Knight-Kit >
        • Knight Kit Span Master II
      • Yaesu FT-817 >
        • Yaesu FT-817ND
        • LDG Z-817 Autotuner
        • Windcamp LiPo Battery
    • Antique Radios >
      • Building A Radio Workbench
      • Radio Dial Neon Clock
      • Radios >
        • 1938 Zenith 6-S-254
        • Echophone EC-1
        • Eltz Radione 2
        • Panasonic RF-5000A
        • Silvertone Model 4465
    • Geiger Counters >
      • AN/PDR-27G Radiac Set
      • Lionel CD V-700 Geiger Counter
      • RCA WF-12A Geiger Counter
    • Test Equipment >
      • DIY Test Equipment >
        • DIY Curve Tracer
        • DIY Signature Tracer
      • Military Test Equipment >
        • BC-221-AF Frequency Meter
        • LM-21 Frequency Meter
        • TS-323/UR Frequency Meter
        • TS-465 C/U Sweep Generator
        • TS-505D/U VTVM
        • TV-3C/U Tube Tester
      • Tube Testers >
        • Alternating Current Sink
        • Drug Store Tester
        • EMC Model 200 Tube Tester
        • Hickok Model 6000A Tube Tester
        • Hickok OZ-1 (550X)
        • Precise Model 111 Tube Tester
        • Precision Model 10-12
        • Supreme Model 385
        • TV-3C/U Tube Tester
      • VTVMs and Multimeters >
        • B&K Model 290 Hi-Low FET Multimeter
        • Hickok 225K VTVM
        • McMurdo Silver VOMAX 900
        • Micronta 22-220 FET Multimeter
        • Simpson 360-2 Digital FET DMM
        • TS-505D/U VTVM
      • Hickok >
        • Hickok 19X RF Generator
        • Hickok 225K VTVM
        • Hickok 288X RF Generator
        • Hickok OZ-1 (550X)
        • Hickok 6000A Tube Tester
      • Simpson >
        • Simpson 360 DMM
        • Simpson 360-2 DMM
        • Simpson 480 Genescope
      • Supreme Instruments >
        • Supreme 385 Automatic
        • Supreme 560 Vedolyzer
        • Supreme 560A Vedolyzer
        • Supreme Model 561 AF/RF Generator
        • Supreme's Model 562 Audolyzer
        • Supreme Model 562 Audolyzer circa 1941
        • Supreme Model 562 Audolyzer circa 1946
        • Supreme Model 563 Audio Generator
        • Supreme Model 576 RF Generator
      • Other Test Equipment >
        • Rider 162 Chanalyst
        • Tektronix 326 O'scope
        • VU-Data Model 941B Oscilloscope
    • ---------------
    • Fossils
    • Rocks and Minerals
    • Star Trek >
      • Star Trek Rock Mood Lamp
      • Star Trek Communicator