6ER5

The 6ER5 is a miniature seven-pin RF tube with frame grid and semiremote-cutoff characteristic. Sylvania describes a VHF amplifier triode; RCA and Tung-Sol particularly document VHF television tuners. RCA RC-30 mentions both color and monochrome receivers. A partial shield between grid and anode reduces direct capacitance, alongside two cathode leads. Sylvania associates these features with easier neutralization and higher input impedance; Tung-Sol emphasizes low cathode-lead inductance.

Editions do not always use the same description. Tung-Sol's tentative July 1, 1960 sheet calls it a frame-grid tetrode and shows grid 2 on pin 6, primarily serving as a shield; June 1, 1963 calls it a high-mu shielded triode and labels that pin internal shield. RCA also calls it a high-mu triode. This documentary difference must retain its date: separate grid-2 limits from the tentative data cannot be applied indiscriminately to the later sheet.

The 6ER5 heater requires 6.3 V, 0.18 A AC or DC. Combined sheets also list 2ER5 and 3ER5; Sylvania gives respectively 2.3 V at 0.6 A and 2.8 V at 0.45 A. Those belong to the other designations, not the 6ER5 heater. The shared point is anode 200 V, control grid −1.2 V, anode current 10 mA, transconductance 10.5 mA/V, amplification factor 80, anode resistance about 8 kΩ. Anode curves also show the 2.2 W dissipation line.

Control tables contain an explicit discrepancy. RCA and Sylvania associate about −3.8 V with transconductance 500 µA/V and −5.6 V with 100 µA/V. Both preserved Tung-Sol tables give 5,000 and 1,000 µA/V at the same nominal biases. These figures are not silently harmonized: stated transconductance differs tenfold. Control curves provide another representation but do not erase the tables' different wording. The 200 V, −1.2 V, 10 mA point agrees across the consulted manufacturers.

Heater-cathode limits also depend on edition. RCA August 1960 gives peak 100 V in either polarity. Sylvania and Tung-Sol 1963 give total DC-plus-peak 200 V with heater negative; with heater positive, 100 V DC and 200 V total. Common anode limits are 250 V, dissipation 2.2 W and cathode current 20 mA; maximum negative control-bias magnitude is 50 V. Maximum grid-circuit resistance is 1 MΩ, Sylvania specifying cathode bias. The 550 V supply entry in Sylvania and Tung-Sol is distinct from the 250 V anode rating.

Without external shielding, grid-anode capacitance is 0.38 pF, input 4.4 pF, output 3 pF; shielded values are respectively 0.36, 4.4 and 4 pF. RCA specifies external shielding to cathode except marked measurements connected to ground. Internal-shield pin 6 is separate from both cathode pins, not one common contact. Base E7-1, B7G, basing 7FP. Triode-sheet bottom view: 1 and 7 cathode, 2 control grid, 3 and 4 heater, 5 anode, 6 internal shield.

Any mounting position is permitted. RCA and Tung-Sol drawings give maximum diameter 3/4 inch, maximum seated height 1 7/8 inches and maximum overall length 2 1/8 inches: 19.05, 47.625 and 53.975 mm. Overall includes pins, seated height the bulb tip. Sylvania's outline 5-2 reference supplies no numerical dimensions on that page. Packaging and photographed-specimen dimensions are not assigned as tube mechanical limits.

Documentation consulted: Sylvania, Types 6ER5 / 3ER5 / 2ER5, sheet 111-4-3-60 and curves, two pages; RCA, 6ER5 High-Mu Triode, August 1960, two pages in two preserved copies; Tung-Sol, 6ER5, tentative July 1, 1960 data, plates 5899 and 5900, and June 1, 1963 sheet, plate 6731, five-page bundle; RCA Receiving Tube Manual RC-30, page 268, 6ER5 entry.