Realistic Model 113 Mutual Conductance Tube Tester - Fully Restored and Calibrated
This is a very nice Precise 111 Tube Tester rebranded by Radio Shack as a Realistic Model 113. It is a professional grade tester that provides one of the most complete tube evaluations available. This tester will check:
1) GM - Mutual Plate Transconductance
2) EM - Cathode Emission
3) Filament Current
4) Leakage and Shorts
In addition to the above tests for vacuum tubes, the Model 113 will test transistors for leakage and gain.
This tester basically uses a Hickok circuit with some added frills.
The Model 113 will test a wide variety of audio tubes including 2A3. Although the roll chart does not list a 300B tube, the 2A3 settings on the chart can be used for a 300B tube with one adjustment. Rather than setting the filament voltage at 2.5 volts as for the 2A3 tube it should be set at 5 volts for the 300B. Also, you will need a known good 300B tube to obtain baseline readings for GM, EM and filament current to which to compare.
As can be seen from the pictures, this vintage tester is in nice cosmetic condition. In addition, it has been totally restored and calibrated. All electrolytic and ceramic disc capacitors have been replaced as well as any off value resistors. Several calibration pots have been replaced with high quality mil spec pots. After these components were replaced, the tester was calibrated to factory specs. I worked as a technician in the audio repair trade for many years, and have the tools, knowledge and skills necessary to properly service this tester, calibrate it to factory specs and thoroughly test all of its functionality. When restoring and calibrating a tester, I take tremendous care. If it's not good enough to keep for myself, I will not sell it to someone else.
The tester comes with the original owner's manual and a photocopy of the roll chart. The roll chart, like the roll charts on many of the older testers, gets stiff at the extreme ends and it is sometimes difficult to read the tube number. Thats why I am providing a photocopy of the roll chart.
This tester will be packed very carefully to ensure that it arrives to its new owner in the condition shown. Like always, no charge for Paypal or packing materials. Buy with absolute confidence. Check my superb feedback here and on E-Bay under the same user name.
Thanks for looking!