TUBE: 6550
FICHIER SOURCE: sheets/127/6/6550.pdf
FABRICANT: Tung-Sol Electric Inc., Electron Tube Division, Bloomfield, New Jersey
ANNÉE: 1963 (JULY 1, 1963 / MARCH 1, 1963; PLATE #6755/6679/6680/6681)
TYPE: Beam Pentode (beam tetrode) power amplifier

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TUNG-SOL 6550 PENTODE
FOR AUDIO SERVICE APPLICATIONS
COATED UNIPOTENTIAL CATHODE, ANY MOUNTING POSITION
GLASS BULB ST-16; LARGE WAFER OCTAL WITH BARRIERS, 7 PIN LOW LOSS B7-99
Dimensions: 2.062" MAX dia, 4.188" MAX, 4.750" MAX
BASING DIAGRAM (BOTTOM VIEW) JEDEC 7AC:
Pin 1 - NO CONNECTION OR BASE SHELL (SEE BELOW)
Pin 2 - H (Heater)
Pin 3 - P (Plate)
Pin 4 - G2
Pin 5 - G1
Pin 7 - H (Heater)
Pin 8 - K,G3 (Cathode, Grid No.3)

"THE 6550 IS A BEAM PENTODE POWER AMPLIFIER PRIMARILY DESIGNED FOR AUDIO SERVICE. IT CARRIES A 42 WATT PLATE DISSIPATION RATING WHICH PROVIDES FOR PUSH-PULL AMPLIFIER DESIGNS UP TO 100 WATTS OUTPUT..."

DIRECT INTERELECTRODE CAPACITANCES (WITHOUT SHIELD):
GRID 1 TO PLATE ... 0.8 pf
INPUT ... 15 pf
OUTPUT ... 10 pf

HEATER CHARACTERISTICS AND RATINGS (Design Maximum Values - EIA Standard RS-239):
AVERAGE CHARACTERISTICS ... 6.3 VOLTS, 1.6 AMP
HEATER SUPPLY LIMITS: VOLTAGE OPERATION ... 6.3 ± 0.6 VOLTS
MAXIMUM HEATER-CATHODE VOLTAGE:
  Heater negative w.r.t. cathode, total DC and peak ... 300 VOLTS
  Heater positive w.r.t. cathode, DC ... 100 VOLTS; total DC and peak ... 200 VOLTS

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MAXIMUM RATINGS (Design Maximum Values - EIA Standard RS-239):
PLATE VOLTAGE, DC ... 660 VOLTS
GRID 2 VOLTAGE, DC:
  PENTODE CONNECTION ... 440 VOLTS
  TRIODE AND ULTRA-LINEAR CONNECTION ... 500 VOLTS
GRID 1 VOLTAGE, DC ... -300 TO 0 VOLTS
PLATE DISSIPATION ... 42 WATTS
GRID 2 DISSIPATION:
  CONTINUOUS ... 6.0 WATTS
  INTERMITTENT-MUSIC OR SPEECH PEAKS ... 10.0 WATTS
CATHODE CURRENT, DC ... 190 MA
GRID 1 CIRCUIT RESISTANCE: FIXED BIAS ... 50 KOHMS; SELF BIAS ... 250 KOHMS
BULB TEMPERATURE ... 250 °C

AVERAGE CHARACTERISTICS (PENTODE CONNECTION):
PLATE VOLTAGE ... 250 VOLTS
GRID 2 VOLTAGE ... 250 VOLTS
GRID 1 VOLTAGE ... -14 VOLTS
PLATE CURRENT ... 140 MA
GRID 2 CURRENT ... 12 MA
TRANSCONDUCTANCE ... 11000 µMHOS
PLATE RESISTANCE, APPROX. ... 15000 OHMS
TRIODE AMPLIFICATION FACTOR ... 8
GRID 1 VOLTAGE FOR 1 MA PLATE CURRENT ... -40 VOLTS

TYPICAL OPERATING CONDITIONS - CLASS A1 AUDIO AMPLIFIER - SINGLE TUBE
PLATE VOLTAGE, DC ... 250 / 400 VOLTS
GRID 2 VOLTAGE, DC ... 250 / 225 VOLTS
GRID 1 VOLTAGE, DC ... -14 / -16.5 VOLTS
PEAK SIGNAL VOLTAGE ... 14 / 16.5 VOLTS
ZERO-SIGNAL PLATE CURRENT ... 140 / 87 MA
MAX-SIGNAL PLATE CURRENT ... 150 / 105 MA
ZERO-SIGNAL GRID 2 CURRENT ... 12 / 4 MA
MAX-SIGNAL GRID 2 CURRENT ... 22 / 14 MA
LOAD RESISTANCE ... 1500 / 3000 OHMS
TOTAL HARMONIC DISTORTION, APPROX. ... 7 / 13.5 PERCENT
MAX-SIGNAL POWER OUTPUT ... 12.5 / 20 WATTS

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TYPICAL OPERATING CONDITIONS (cont'd)
PUSH-PULL CLASS AB1 AUDIO AMPLIFIER - PENTODE CONNECTION (avg values 2 matched tubes; SELF BIAS / FIXED BIAS columns):
PLATE VOLTAGE, DC ... 400 / 400 / 450 / 600 VOLTS
GRID 2 VOLTAGE, DC ... 310 / 270 / 310 / 300 VOLTS
GRID 1 VOLTAGE, DC ... --- / -23 / -29.5 / -32.5 VOLTS
COMMON CATHODE RESISTOR BYPASSED ... 140 / --- / --- / --- OHMS
PEAK GRID-TO-GRID SIGNAL VOLTAGE ... 43 / 46 / 58 / 65 VOLTS
ZERO-SIGNAL PLATE CURRENT ... 170 / 170 / 150 / 100 MA
MAX-SIGNAL PLATE CURRENT ... 185 / 275 / 295 / 270 MA
ZERO-SIGNAL GRID 2 CURRENT ... 10 / 9 / 9 / 5 MA
MAX-SIGNAL GRID 2 CURRENT ... 25 / 35 / 38 / 33 MA
EFFECTIVE LOAD, PLATE-TO-PLATE ... 5000 / 3500 / 3500 / 5000 OHMS
TOTAL HARMONIC DISTORTION, APPROX. ... 0.7 / 0.6 / 1.5 / 3.0 PERCENT
MAX-SIGNAL POWER OUTPUT ... 40 / 60 / 77 / 100 WATTS

PUSH-PULL AUDIO AMPLIFIER, ULTRA-LINEAR OPERATION (Grid 2 tapped at 40% primary turns; SELF BIAS Class A1 / FIXED BIAS Class AB1):
PLATE AND GRID 2 VOLTAGE, DC ... 395 / 450 VOLTS
GRID 1 VOLTAGE, DC ... --- / -48 VOLTS
COMMON CATHODE RESISTOR BYPASSED ... 200 / --- OHMS
PEAK GRID-TO-GRID SIGNAL VOLTAGE ... 70 / 96 VOLTS
ZERO-SIGNAL PLATE CURRENT ... 170 / 150 MA
MAX-SIGNAL PLATE CURRENT ... 174 / 265 MA
ZERO-SIGNAL GRID 2 CURRENT ... 12.5 / 12 MA
MAX-SIGNAL GRID 2 CURRENT ... 23 / 38 MA
EFFECTIVE LOAD, PLATE-TO-PLATE ... 5600 / 4000 OHMS
TOTAL HARMONIC DISTORTION (APPROX.) ... 1.5 / 2.4 PERCENT
MAX-SIGNAL POWER OUTPUT ... 34 / 70 WATTS

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[courbes seules — plate characteristics Ec2=250V (Ib vs Vp); grid 2 current Ec2=250V]

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[courbes seules — plate characteristics Ec2=300V; grid 2 current Ec2=300V]

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[courbes seules — transfer Eb=500V (Ib vs Eg1, Ec2 family); triode connected plate characteristics]

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[courbes seules — ultra-linear plate characteristics Ec2=450+.40ΔEp; power output & THD vs plate-to-plate load]

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[courbes seules — PP Class AB1 ultra-linear (Eb=450,Ec2=450,Ec1=-48,RL=4000); PP Class AB1 (Eb=450,Ec2=310,Ec1=-29.5,RL=3500)]