8122
Power Tube
Linear Beam Power Tube
Coaxial-Electrode Structure
Ceramic Metal Seals
Full Ratings up to 500 MHz
Forced-Air Cooled
380 Watts PEP Output at 30 MHz AB
570 Watts PEP Output at 30 MHz AB
300 Watts CW Output at 470 MHz
Matched Pair Available
1
2
BURLE-8122 is a very small, low-cost, forced-air-
cooled beam power tube designed for use as an RF
power amplifier, oscillator, regulator, distributed
amplifier, or linear RF power amplifier in mobile or
fixed equipment.
The 8122 features a light-weight, cantilever-supported
cylindrical electrode structure within a ceramic-metal
envelope. This construction provides a very sturdy
tube and permits high-temperature operation.
The terminal arrangement of the 8122 facilitates use
of the tube with tank circuits of the coaxial or stripline
type. Effective isolation of the output circuit from the
input circuit is provided at the higher frequencies by
the low-inductance ring terminal for grid-No. 2. A base-
pin termination for grid-No. 2 is also available for
operation of the 8122 at the lower frequencies.
The tripod arrangement of both the cathode and the
grid-No. 1 leads not only simplifies construction, but
enhances electrical characteristics. The three cathode
leads reduce the inductance path to RF ground and
reduce the input admittance at high frequencies.
This data sheet gives application information
unique to the BURLE 8122. It is to be used in
conjunction with the publication, “Application
Guide for BURLE Power Tubes, TP-105”, for
general application information.
The three grid-No.1 leads to separate pins
accommodate a split-input circuit for distributed
amplifier service.
The BURLE 8122/V1 is the designation for a matched
pair of Type 8122 Beam Power Tubes for use in
equipments not having individual bias adjustment. This
pair is matched to assure balanced operation within a
bias range of 28 to 40 volts, so that each tube will have
an approximately equal anode current during zero-
signal and signal operation. Such matching also
assures efficient, full system operation and gives
optimum life expectancy.
General Data
Electrical:
Heater, for Unipotential Cathode:
Voltage (AC or DC)
Current at 13.5 volts 1.3 A
Minimum heating time 60 s
Mu-Factor, Grid No. 2 to Grid No. 1
for Anode Volts = 450, Grid-No. 2
Volts = 325, and Anode Amperes =1.2 12
Direct Interelectrode Capacitances:
Grid No. to anode………………. 0.15 max. pF
Grid No. 1 to cathode………….. 16.3 pF
Anode to cathode………………. 0.01 pF
Grid No. 1 to grid No 2………… 23.3 pF
Grid No. 2 to anode……………. 7.0 pF
Grid No. 2 to cathode………….. 2.7 pF
Cathode to heater……………… 3.3 pF
1
13.5 ±. 10% volts
2
Mechanical:
Operating Position……………………………………….. Any
Maximum Overall Length………………………………. 2.26”
Seated Length……………………………... 1.920” ± 0.065”
Greatest Diameter………………………… 1.625” ± 0.015"
Base…………….. Large-Wafer Elevenar 11-Pin with Ring
(JEDEC No. E11-81)
Socket…………………. JettroncNo. CD77-030,
JohnsonaNo. 124-311-100,
EriebNo. 9813-000, or equivalent
Grid No.2 Bypass
Capacitor………………
JohnsonaNo. 124-0113-001,
EriebNo. 9812-000, or equivalent
Weight (Approx.)………………………………………. 3.5 oz
Thermal:
Terminal Temperature (All terminals)….. 250 max ºC
Radiator Core Temperature
(See Dimensional Outline)……………… 250 max ºC
Air Flow:
See Figure 1 - Typical Cooling Requirements
Linear RF Power Amplifier
Single-Sideband Suppressed-Carrier Service
Peak envelope conditions for a signal having a minimum
peak-to-average power ratio of 2
Maximum CCS Ratings, Absolute-Maximum Values:
DC Anode Voltage
Up to 30 MHz………………………... 3000
Up to 500 MHz……………………… 2200 volts
Up to 500 MHz
DC Grid-No. 2 Voltage………………... 400 volts
DC Grid-No. 1 Voltage……………….. -100 volts
DC Anode Current at Peak
Of Envelope……………………………. 450
DC Grid-No. 1 Current……………….. 100 mA
Anode Dissipation……………………. 400 watts
Grid-No. 2 Dissipation……………….. 8 watts
Peak Heater-Cathode Voltage
Heater negative with respect
to cathode…………………………….. 150 volts
Heater positive with respect
to cathode…………………………….. 150 volts
Maximum Circuit Values:
Grid No. 1 Circuit Resistance Under Any Condition:
With fixed bias………………………….. 25,000 ohms
With fixed bias (In Class AB1operation 100,000 ohms
With cathode bias…………………… Not recommended
Grid-No. 2 Circuit Impedance8………… 10,000 ohms
Anode Circuit Impedance……………… See Notes 4 and 6
Typical CCS Operation at 30 MHz with “Two-Tone
Modulation”:
AB
1
DC Anode Voltage…………….. 2000 2500 volts
DC Grid-No. 2 Voltage………... 400 400 volts
DC Grid-No. 1 Voltage……….. -35 -35 volts
Zero-Signal DC Anode Current 100 115 mA
Effective RE Load Resistance.. 3050 3500 ohms
a. E. F. Johnson Co., 299 Johnson Ave., Waseca, MN 56093.
b. Erie Specialty Products, 645W. 11th St., Erie, PA 16512.
c. Jettron Products, Inc., 56 Route 10, Hanover, NJ 07936
AB
4
volts
5
2
mA
9
DC Anode Current at Peak
of Envelope…………………………
335 400 mA
Average DC Anode Current………. 250 275 mA
DC Grid-No. 2 Current at
Peak of Envelope………………….. 10 6 mA
Average DC Grid-No 2 Current…… 7 4 mA
DC Grid-No. 1 Current at
Peak of Envelope………………….. 0.05
7
3mA
Peak-Envelope Driver Power
Output (Approx.)……………………. 0.3 0.5 watt
Output-Circuit Efficiency (Approx.).. 90 90 %
Distortion Products Level:
Third order………………………... 29
10
28 db
Fifth order………………………… 32 32 db
Useful Power Output (Approx.)
Average…………………………… 190 285 watts
Peak envelope…………………… 380 570 watts
RF Power Amplifier & Oscillator - Class C
Telegraphy and RF Power Amplifier -
Class C FM Telephony
Maximum CCS Ratings, Absolute-Maximum Values:
Up to 500 MHz
DC Anode Voltage…………………………… 2200 volts
DC Grid-No. 2 Voltage………………………. 400 volts
DC Grid-No. 1 Voltage………………………. -100 volts
DC Anode Current…………………………… 300 mA
DC Grid-No. 1 Current………………………. 100 mA
Grid-No. 2 Dissipation………………………. 8 watts
Anode Dissipation…………………………… 400 watts
Peak Heater-Cathode Voltage:
Heater negative with respect
to cathode………………………………….. 150 volts
Heater positive with respect
to cathode………………………………….. 150 volts
Maximum Circuit Values:
Grid-No. 1 Circuit Resistance Under Any Condition:
With fixed bias………………………… 25,000 ohms
Grid-No. 2 Circuit Impedance………….. 10,000 ohms
Anode Circuit Impedance……………….. See Note 6
Typical CCS Operation:
In Grid-Drive Circuit at 50 MHz
DC Anode Voltage 700 1000 1500 1200 volts
DC Grid-No. 2 Voltage 175 200 200 200 volts
DC Grid-No. 1 Voltage -10 -30 -30 -30 volts
DC Anode Current 300 300 300 300 mA
DC Grid-No. 2 Current 25 20 20 20 mA
DC Grid-No. 1 Current 50 40 40 30 mA
Driver Power Output
(Approx) 1.2 2 2 2 watts
Useful Power Output 120 175 275 375 watts
In Grid-Drive Circuit at 470 MHz
DC Anode Voltage 700 1000 1500 2000 volts
DC Grid-No. 2 Voltage 200 200 200 200 volts
DC Grid-No. 1 Voltage -30 -30 -30 -30 mA
DC Anode Current 300 300 300 300 mA
DC Grid-No. 2 Current 10 10 5 5 mA
DC Grid No. 1 Current 30 30 30 30 mA
Driver Power Output
Approx.) 5 5 5 5 watts
Useful Power Output 100 165 235 300 watts
Plate-Modulated RF Power Amplifier
Class C Telephony
Carrier conditions per tube for use with a max. modulation
factor of 1.0
Maximum CCS Ratings, Absolute-Maximum Values:
Up to 500 MHz
DC Anode Voltage……………………….. 1800 volts
DC Grid-No. 2 Voltage………………….. 400 volts
DC Grid-No. 1 Voltage…………………. -100 volts
DC Anode Current………………………. 250 mA
DC Grid-No.1 Current…………………… 100 mA
Grid-No. 2 Input………………………….. 5 watts
Anode Dissipation………………………... 280 watts
Characteristics Range Values
Min. Max.
Heater Current11………………….. 1.15 1.45 A
Direct Interelectrode Capacitances
Grid-No.1toplate2…………….. - 0.15 pF
Grid-No. 1 to cathode2………… 14.6 18.0 pF
Plate to cathode2………………. 0.004 0.016 pF
Grid-No.1togrid-No.22……… 20.0 26.5 pF
Grid-No.2toplate
Grid-No. 2 to cathode2………… 2.1 3.3 pF
Cathode to heater2……………. 2.5 4.1 pF
Grid-No. 1 Voltage
Reverse Grid-No. 1 Current
Grid-No. 2 Current
Peak Emission
Interelectrode Leakage
Resistance14……………………… 50 - megohm
Zero Bias Anode Current11’15…… 1.0 1.8 A
1. Because the cathode is subjected to back bombardment
as the frequency is increased with resultant increase in
temperature, the heater voltage should, for optimum life,
be reduced to a value such that at the heater voltage
obtained at minimum supply voltage conditions (all other
voltages constant) the tube performance just starts to
show some degradation; e.g., at 470 MHz heater volts =
12.5 (approx.)
2. Measured with special shield adapter.
3. See TP-105
4. For operation above 2200 anode volts, the tube shall see
an effective anode-supply impedance of no less than 750
ohms. A fault current limiting resistor of no less than 15
ohms is to be used between the output filter capacitance
and the tube anode. The anode-supply-output-filter
capacitance is to be no greater than 10 microfarads.
5. The maximum rating for a signal having a minimum
peak-to-average power ratio less than 2, such as is
obtained in “Single-Tone” operation, is 300 mA. During
2
…………… 6.3 7.7 pF
11, 12
………….. -8 -19 volts
11, 12
11 ,12
1112
………….. -5 +6 mA
……………….. 13 - peak A
.- -25 mA
short periods of circuit adjustment under ‘Single-Tone”
conditions, the average anode current may be as high as
450 mA.
6. The tube should see an effective anode supply
impedance which limits the peak current through the tube
under surge conditions to 15 amperes.
7. This value represents the approximate grid-No. 1 current
obtained due to initial electron velocities and contact-
potential effects when grid-No. 1 is driven to zero volts at
maximum signal.
8. A fault current limiting resistor of no less than 320 ohms
is to be used between the screen output filter
capacitance and the tube screen. The screen supply
output filter capacitance is to be no greater than 80
microfarads.
9. A fault current limiting resistor of no less than 20 ohms is
to be used between the bias supply output filter
capacitance and the tube grid-No. 1. The bias supply
output filter capacitance is to be no greater than 150
microfarads.
10. The value of third order distortion product level shown
may be improved by approximately 5dB by utilizing an
unbypassed, noninductive 20-ohm resistor between the
cathode and ground; a slight increase in drive power will
be required.
11. With 13.5 volts ac or dc on heater.
12. With dc plate voltage at 700 volts, dc grid-No. 2 voltage
of 250 volts, and dc grid-No. 1 voltage adjusted to give a
dc anode current of 185 mA.
13. For conditions with grid-No. 1, grid No. 2, and anode tied
together; and pulse voltage source connected between
anode and cathode. Pulse duration is 2.5 microseconds
and pulse repetition frequency is 60 pps. The voltage-
pulse amplitude is 200 volts peak. After 1 minute at this
value, the current-pulse amplitude will not be less than
the value specified.
14. Under conditions with tube at 20º to 30 ºC for at least 30
minutes without any voltages applied to the tube. The
minimum resistance between any two electrodes as
measured with a 200-volt Meggertype ohmmeter having
an internal impedance of 1 .0 megohm, will be no less
than the value specified.
15. With dc anode voltage of 450 volts, dc grid-No. 2 voltage
of 400 volts, dc grid-No. 1 voltage of -100 volts, grid drive
voltage to zero. With pulse duration of 4500 to 5000
microseconds and pulse repetition frequency of 10 to 12
pps.
Operating Considerations for Type 8122/V1-
Matched Pair
Follow all of the recommendations and instructions outlined
by the equipment manufacturers with special emphasis on
the following precautions:
1. Always allow at least three minutes for the tube heaters
to warm up before any other voltages are applied or
before any current is drawn.
2. During CW tune-up procedure, the total screen current
for both tubes should never exceed 15 milliamperes.
3. During CW tune-up procedure the total anode current for
both tubes should never exceed 550 milliamperes.
4. In the SSB mode, the total anode current for both tubes
should not exceed 400 milliamperes during voice peaks.
A sustained tone like a whistle should not be permitted.
5. Check the socket wiring to assure that each of the three
pins provided for the cathode, grid and screen electrodes
are interconnected rather than using one pin for each
electrode. (See basing diagram of tube bulletin.)
6. Use only 8122/V1 for “matched pair” performance.
If an unmatched pair is used in a parallel circuit not
having individual bias adjustment for each tube, one tube
will carry most of the load current and, consequently, will
be operated out of ratings.
7. Never rap a tube or equipment. Each tube of the
8122/V1 set has closely spaced electrodes which control
the tube’s electrical characteristics. Bumping or rapping
the tubes or the equipment may change the spacings,
thereby destroying the matched characteristics of the
tubes.
8. The operating voltages applied to these devices presents
an electrical shock hazard. The tubes and associated
apparatus should be housed in a protective enclosure to
keep all personnel from coming in contact with high
voltage. The protective enclosure should be designed
with interlocks to break the primary circuit of the high-
voltage supplies, discharging high-voltage capacitors
when any door or gate on the protective housing is
opened, and should prevent the closing of the primary
circuit until the door or gate is again closed.
9. DO NOT use the remaining tube of a matched pair with
any other remaining or new tube. The tubes will be
unbalanced and will fail prematurely.
References
1. Application Guide for BURLE Power Tubes, TP-105.
2. Screen-Grid Current Loading and Bleeder
Considerations, TP-122
3. Application Guide for Forced Air Cooling of BURLE
Power Tubes TP-118
Figure1–TypicalCoolingRequirements
Figure 2 - Typical Constant-Current Characteristics For Grid-No. 2 Voltage = 400 Volts
Figure 3 - Typical Anode characteristics - For
Grid-No. 2 Voltage = 400 Volts
Figure 4 - Typical Characteristics - For
Grid-No. 2 Voltage = 400 Volts
Figure 5 - Typical constant-current characteristics For Grid-No. 2 Voltage = 250 Volts
Note 1: Keep all stippled regions clear. Do not allow contacts or circuit
components to protrude into these annular volumes.
Note 2: The diameters of the radiator, grid-No. 2 terminal contact
surface, and pin circle to be concentric within the following
values of maximum full indicator reading:
Radiator to Grid-No. 2
Terminal Contact Surface……………………… 0.030” max.
Radiator to Pin Circle…………………………… 0.040” max.
Grid-No. 2 Terminal Contact
Surface to Pin Circle…………………………… 0.030” max.
Note 3: The full indicator reading is the maximum deviation in radial
position of a surface when the tube is completely rotated about
the center of the reference surface. It is a measure of the total
effect of run-out and ellipticity.
Figure 6 - Dimensional Outline
* This dimension around the periphery of any individual pin
may vary within the limits shown.
Figure 7 - Base Drawing Large-Wafer
Elevenar 11-Pin With Ring JEDEC No. E11-81
Pin1: Cathode Pin 9: Cathode
Pin2: Grid-No.2 Pin 10: Grid-No.2
Pin3: Grid-No.1 Pin 11: Grid-No.1
Pin4: Cathode Cap: Anode Terminal
Pin5: Heater Radiator: Anode Terminal
Pin6: Heater Ring: Grid-No. 2 Terminal Contact
Pin7: Grid-No.2 Surface (For use at higher frequen-
Pin8: Grid-No.1 cies)
Figure 8 - Basing Diagram - Bottom View
Figure 9 - Gauge Drawing JEDEC No. GE11-1
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