MORNING STAR OBSERVATORY
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Alternating Current Sink (ACS) 

To check transconductance accuracy I built the Alternating Current Sink (ACS) test device detailed in the paper "Calibration Principles - Hickok Transconductance Testers TV-10, TV-7" written by Dr. H. Holden on the worldphaco.com website (just look for the Hickok TV-10 link on the site). It's a simple circuit, consisting of only two power transistors and some resistors, but provides a calibrated current source for checking transconductance accuracy. It's a clever little device and it also works fine in my TV-3C/U tester.

I didn't have the time to make the printed circuit boards shown in the paper so I built my ACS on prototyping board. I found a couple of 800V power transistors (originally made for TV vertical deflection circuits) in one of my parts bins and the only other parts needed are the resistors and an octal tube base.

In the photo the ACS is being calibrated by measuring the voltage across a precision resistor in one leg of the circuit and using that measurement to calculate what the voltage in the second leg should be. Then the emitter resistor in the second leg is adjusted to calibrate the unit. The whole procedure is detailed in the paper but what's really slick about the ACS is it can be calibrated in the tube tester using only a digital voltmeter.


In use the ACS plugs into the octal socket of the tube tester which is set up as if testing a 6J5, except the filament is set to 10V. The ACS is designed to give a reading of 1000 umhos as read on the B scale when the tester is set to the B, D or E ranges. On the C range the reading will be 500 umhos also read on the B scale.
Picture

Picture
At left is a photo of my ACS without all the clip leads used during calibration. After calibrating it I used it to check the calibration of my TV-3C tester and now I can use the calibrated TV-3C to compare test results with other tube testers I restore.

Since the calibration of the ACS is only as accurate as the DVM used, I purchased a small precision voltage source from eBay just to verify my DVM's calibration. It was inexpensive and I've used it to check all my meters. This model outputs 2.5V, 5.0V, 7.5V and 10V at the push of a button. The calibration data is on a sticker on the bottom and is specified to more digits than my meter can measure.
Picture
Picture

Last update on 12/6/2017
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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