High Fidelity Tubes

High-vacuum diodes are limited to output currents of about 300mA maximum. Higher current outputs than this from vacuum diodes require tubes of excessive size if satisfactory efficiency is to be maintained. The mercury-vapor rectifier diode has a much higher current capacity because of the introduction of a small amount of mercury into its envelope. As the cathode is heated, a portion of the mercury vaporizes, filling the envelope with vapor. The mercury vapor greatly reduces the internal resistance of the diode, so that the tube can carry large values of current with only a small voltage drop.

The picture above shows the operation of the mercury-vapor rectifier and how the introduction of mercury vapor reduces the cathode-to-plate voltage drop. When the plate is positive with respect to the cathode, it attracts some of the electrons emitted by the cathode. Other electrons remain near the cathode, forming what is known as a space charge; this tends to limit the electron flow to the plate. The electrons traveling toward the plate encounter the mercury-gas atoms. When they collide, electrons are knocked loose from the mercury atoms. The mercury atoms that have thus lost electrons become positive ions. The positive ions neutralize some of the space-charge electrons which surround the heated cathode, so more electrons are able to move toward the plate. As they do, they strike additional ions. This process “snowballs,” producing a large flow of electrons between cathode and plate.

The Tung-Sol 83 Mercury-Vapor Rectifier made in USA, as often found in Hickok tube testers. Average price on eBay $45-$65 (2011)

Remark: When mercury-vapour tubes are first placed in service, and each time after the mercury has been disturbed, such as by removal from the socket to the horizontal position, they should be run with filament voltage only for 30 minutes before applying high voltage. After that a delay of 30 seconds is recommended each time the filament is turned on.

Model 533DM, Dealers who are using this tube tester enthusiastically report that it is the best salesman they ever used. Customer convincing, the 533-DM contains a huge, illuminated nine-inch meter that clearly and accurately shows condition of the tube under test. Dual-scale provides micromho readings for the technician and a multi-color “Good”, “Replace” scale for easy customer interpretation across the counter.

“Attractive Display Model and Most Effective Tube Salesman”

Contains the Hickok Tube Gas Test, and a circuit for accurate forcast of future tube life. Detects more weak tubes. Tests all the latest tubes including television. 9″ chrome meter case, satin finish aluminum panel. Strong , attractive, enameled steel case. 110-130 V.A.C. Price: $199.20 (1953).

Model 700, most accurate tube tester available for precise development laboratory measurement of Mutual Conductance. Provides 4 seperate signal voltages with micromho ranges from 1500 to 60,000. Duplicates results in tube manuals. Places separate voltage on each element of the tube. Voltages can be varied and measured separately in each circuit. Provides means for complete curve study of any particular tube. Designed to never become obsolete. Complete with all leads. Price: $750 (1953).

“Laboratory Model”

Model 7001, Additional Null Reading Device, for use with the Model 700 for obtaining bridge type null readings with accuracy of ½ of 1%. Case matched to the set Price: $162.30 (1953).

Model 7002, Short and Leakage Test Accessory for use with the Model 700 to check for shorts between all elements. Matched to the set. Price: $145.00 (1953).

Model 533AC, a lower cost dealer’s counter model. Attractively designed to set on the counter and increase your tubes sales. Highly accurate Dynamic Mutual Conductance circuits. Encourages customers to bring their tubes in where they can see the actual test. If customers’ tubes check “OK” you have an excellent opportunity to invite him to bring his receiver in for a thorough check of all its circuits. With the 533-AC you will build customer confidence, increase tube sales and promote your complete radio and TV service.

“Dynamic Mutual Conductance in A Smaller Counter Model”

Satin finished aluminum panel. Beautifully styled, blue enameled steel case.

Specifications: Dual-scale meter provides readings in microhoms for the techinician and “Good”, “Replace” scale for easy customer interpretation. Quick, impressive, accurate, and dependable. Detects more weak, ordinarily passable tubes. Contains the Hickok Tube Gas Test, and a circuit for accurate forecast of future tube life. Simple to operate. Contains all necessary tube information on a handy built-in roll chart. Tests tubes under simulated operating conditions. Tests all the latest tubes including television. Large 5″ easy-to-read meter scale and calibrated GM circuit provide increased accuracy in testing today’s newer tubes. Price: $185.80 (1953).