4CX250B-M [CPI]
RADIAL BEAM POWER TETRODE; RADIAL束功率四极管
| 型号： | 4CX250B-M |
| 厂家： | 
COMMUNICATIONS & POWER INDUSTRIES, INC. |
| 描述： | RADIAL BEAM POWER TETRODE |
| 文件： | 总7页 (文件大小：875K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
RADIAL BEAM POWER TETRODE
4CX250B/M
7203A
ChARACTERISTICS1
ELECTRICAL
Cathode: Oxide coated, Unipotential
The Eimac 4CX250B/M is a ceramic/metal,
forced-air cooled external-anode tetrode with a
maximum anode dissipation rating of 250 Watts.
The 4CX250B/M is intended for use in applica-
tions where tight control of electrical specifica-
tions is required and replaces the 4CX250B in
all applications. This tube utilizes a ruggedized
internal structure and utilizes a welded anode cap
for improved reliability.
Filament Voltage
6.0 0.3
2.6
V
A
Current at 6.0 Volts
Direct Interelectrode Capacitances (grounded cathode)2
Cin
Cout
Cgp
15.7 pF
4.5 pF
0.04 pF
5
Amplification Factor, Average (screen-grid)
Frequency of Maximum Ratings (CW)
500 MHz
MECHANICAL:
Overall Dimensions:
Length
Diameter
2.46 in; 62.5 mm
1.64 in; 41.7 mm
4 oz; 113 gm
Any
Weight (approx.)
Operating Postition
Maximum Operating Temperature:
Ceramic/Metal Seals & Envelope
Anode Core
250° C
250° C
Cooling
Forced Air
Base
Special, 9-pin Jedec-B8-236
Recommended Air System Socket
Recommended Air Chimney
SK-600 Series
SK-606
1 Characteristics and operating values are based upon performance tests. These figures may change without notice as the result of additional data or product refinement.
CPI MPP, Eimac Operation should be consulted before using this information for final equipment design.
2 Capacitance values are for a cold tube as measured in a special shielded fixture in accordance with Electronic Industries Association Standard RS-191.
RANGE VALUES FOR EQUIPMENT DESIGN
Min.
Nom.
Max.
Filament Current @ 6.0 Volts
Catꢀode Warm-up Time
2.3
30
--
60
2.9
--
Amperes
Seconds
Interelectrode Capacitance 1 (grounded catꢀode circuit)
Cin
14.2
4.0
--
--
--
--
17.2
5.0
0.06
pF
pF
pF
Cout
Cgp
Interelectrode Capacitance 1 (grounded grid circuit)
Cin
--
4.0
--
13.0
--
0.01
--
5.0
--
pF
pF
pF
Cout
Cpk
1 Capacitance values are for a cold tube as measured in a sꢀielded fixture in accordance witꢀ Electronic Industries Assocation Standard RS-191.
The values listed above represent specified limits for the product and are subject to change. The data should be used for basic
information only. Formal, controlled specifications may be obtained from CPI for use in equipment design.
For information on this and other CPI products, visit our website at: www.cpii.com,
or contact: CPI MPP, Eimac Operation, 607 Hansen Way, Palo Alto, CA 94303
telephone: 1(800) 414-8823. fax: (650) 592-9988 | email: powergrid@cpii.com
July 2011
1
RADIAL BEAM POWER TETRODE
4CX250B/M
7203A
RADIO FREQUENCY AMPLIFIER
Class C, CW Operation
TYPICAL OPERATION
Measured Values, Grid-Driven
ANODE VOLTAGE
SCREEN VOLTAGE
GRID VOLTAGE
500
250
-90
250
45
1000
250
-90
250
38
1500 2000 Vdc
ABSOLUTE MAXIMUM RATINGS:
250
-90
250
21
250 Vdc
-90 Vdc
ANODE VOLTAGE
2000 Vdc
300 Vdc
ANODE CURRENT
SCREEN CURRENT
GRID CURRENT1
DRIVING POWER2
USEFUL OUTPUT3,4
1 Approximate Values
250 mAdc
19 mAdc
26 mAdc
2.9 Watts
390 Watts
SCREEN VOLTAGE
ANODE CURRENT
0.250 Adc
250 Watts
12 Watts
35
31
28
PLATE DISSIPATION
SCREEN DISSIPATION
GRID DISSIPATION
HEATER-TO-GRID VOLTAGE
4.0
70
3.5
3.2
280
190
2
Watts
150 Volts
2 Approximate, measured in VHF service
3 Approximate, delivered to the load
4 For measured case; may vary from tube to tube
NOTE: TYPICAL OPERATION data are obtained from direct measurement or by calculation from published characteristic curves. Adjustment
of the rf grid voltage (feedback) to obtain the specified anode current at the specified bias and anode voltages is assumed. If this procedure is
followed, there will be little variation in output power when the tube is changed.
APPLICATION
MEChANICAL
MOUNTING - The 4CX250B/M may be mounted in any position.
SEA LEVEL
10,000 FEET
Anode
Dissipation Air Flow Pressure
SOCKETING - The Eimac SK-600 series air system sockets or a
socket having equivalent characteristics is required. Sockets are
available with or without built-in screen capacitors and may be
obtained with either grounded or ungrounded cathode terminals.
Air Flow
(CFM)
Pressure
Drop
(In. of Water)
(Watts)
(CFM)
Drop
(In. of Water)
200
250
5.0
6.4
0.52
0.82
7.3
9.3
0.76
1.20
COOLING – Sufficient forced-air cooling must be provided for
the anode, base seals, and body seals to maintain operating tem-
peratures below the rated maximum values. Air requirements to
maintain anode core temperatures at 200°C with an inlet air tem-
perature of 50°C are tabulated below. These requirements apply
when a socket of the Eimac SK-600 series and an Eimac SK-606
chimney are used with an air flow in the base-to-anode direction.
Tube life is prolonged if the anode temperature is maintained at
values lower than the maximum rating.
At 500 MHz or below base cooling air requirements are satisfied
automatically when the tube is used in an EIMAC Air-System
socket and the recommended air flow rates are used. Experience
has shown that if reliable long life operation is to be obtained, the
cooling air flow must be maintained during standby periods when
only the heater voltage is applied to the tube. The anode cooler
should be inspected periodically and cleaned when necessary to
remove any dirt which might interfere with effective cooling.
The blower selected in a given application must be capable of
supplying the desired airflow at a back pressure equal to the
pressure drop shown in the chart plus any drop encountered in
ducts and filters. The blower must be designed to deliver neces-
sary airflow at the desired altitude.
VIBRATION – The 4CX250B/M is capable of withstanding shock
and vibration, such as encountered in shipment and normal han-
dling. The tubes will function well in environments where shock
and vibration are anticipated.
2
RADIAL BEAM POWER TETRODE
4CX250B/M
7203A
indicated by grid-current values below approx. 15 mA. The
maximum permissible grid-circuit resistance per tube is 100K
Ohms.
ELECTRICAL
HEATER OPERATION - The rated heater voltage for the
4CX250B/M, 6.0 volts as measured at the socket, should be
maintained at this value to obtain optimum performance and
maximum tube life. In no case should the voltage be allowed to
deviate from 6.0 volts by more than plus or minus five percent
(5%). Short-time changes of +/- 10% will not damage the tube,
but variations in performance must be expected. The heater
voltage must be maintained within +/- 5% to minimize these
variations and to obtain maximum tube life.
SCREEN OPERATION - The maximum rated dissipation for
the screen grid is 12 Watts and the screen input power must
be kept below that level. The product of peak screen current
and peak screen voltage approximates the screen input power
when amplitude modulation is used. In some cases screen cur-
rent may tend to be negative. The 4CX250B/M shows reduced
screen current, compared to the 4CX250B, and is therefore
preferred for use in amplifiers where screen supply voltage
regulation is poor or where an increase in screen current above
the normal value will cause a significant reduction in voltage.
At UHF increased output (cavity) loading is recommended to
reduce screen current even if the overall tube efficiency is re-
duced somewhat.
At frequencies above approx. 300 MHz transit-time effects be-
gin to influence the cathode temperature. The amount of driving
power diverted to heating the cathode by back-bombardment
will depend upon frequency, anode current, and driving power.
When the tube is driven to maximum input as a class-C ampli-
fier, the heater voltage should be reduced according to the table
below:
FAULT PROTECTION - All power tubes operate at voltages
which can cause severe damage in the event of an internal arc,
especially in those cases where large amounts of stored en-
ergy or follow-on current are involved. Some means of protec-
tion is advised in all cases, and it is recommended that a series
resistor be used in the anode circuit (20 to 50 ohms) to limit
peak current and provide a means of dissipating the energy in
the event of a tube or circuit arc. For an oxide-cathode tube
such as the 4CX250B/M a maximum of 4 joules total energy
may be permitted to be dumped into an internal arc. Amounts
in excess of this may permanently damage the cathode or the
tube grids. Additional information is found Eimac’s Application
Bulletin #17 titled “FAULT PROTECTION,” available on request.
Frequency Mhz
300 and lower
301 to 400
heater Voltage
6.00 Volts
5.76 Volts
401 to 500
5.50 Volts
CATHODE OPERATION - The oxide coated unipotential cathode
must be protected against excessively high emission currents.
The maximum rated dc input current is 200 mA for plate modu-
lated operation and 250 mA for all other types of operation with
the exception of pulsed applications.
RF RADIATION - Avoid exposure to strong rf fields even at rela-
tively low frequency. Absorption of rf energy by human tissue
is dependent on frequency. Under 300 MHz most of the en-
ergy will pass completely through the human body with little
attenuation or heating affect. Public health agencies are con-
cerned with hazard even at these frequencies. OSHA (Occu-
pational Safety and Health Administration) recommends that
prolonged exposure to rf radiation should be limited to 10 mil-
liwatts per square centimeter.
The cathode is connected internally to four pins and all four
should be used to make connection to external circuits to low-
er inductance. At radio frequencies it is important to keep the
cathode leads short and direct and to use conductors with large
areas to minimize the inductive reactances in series with the
cathode leads.
It is recommended that the rated nominal heater voltage be ap-
plied for a minimum of 30 seconds before other operating volt-
ages are applied. Where the circuit design requires the cathode
and heater to be operated at different potentials, the rated
maximum heater-to-cathode voltage of 150 voltage should be
observed, regardless of polarity.
INTERELECTRODE CAPACITANCE - The actual internal inter-
electrode capacitance of a tube is influenced by many variables
in most applications, such as stray capacitance to the chassis,
capacitance added by the socket used, stray capacitance be-
tween tube terminals, and wiring effects. To control the actual
capacitance values within the tube, as the key component
involved, the industry and the Military Services use a standard
test procedure as described in Electronic Industries Associa-
tion Standard RS-191. This requires the use of specially con-
structed test fixtures which effectively shield all external tube
leads from each other and eliminates any capacitance reading
to “ground”. The test is performed on a cold tube. Other fac-
tors being equal, controlling internal tube capacitance in this
way normally assures good interchangeability of tubes over a
GRID OPERATION - The maximum rated dc grid bias voltage is
-250 volts and the maximum grid dissipation rating is 2.0 Watts.
In ordinary audio and rf amplifiers the grid dissipation usually
will not approach the maximum rating. At operating frequen-
cies above the 100 MHz region, driving power requirements for
amplifiers increase noticeably. At 500 MHz as much as 20 Watts
of driving power may have to be supplied. However, most of the
driving power is absorbed in circuit losses other than grid dis-
sipation, so that grid dissipation is only increased slightly. Sat-
isfactory 500 MHz operation of the tube in a stable amplifier is
3
RADIAL BEAM POWER TETRODE
4CX250B/M
7203A
period of time, even when the tube may be made by different
manu-facturers. The capacitance values shown in the manu-
facturer’s technical data, or test specifications, normally are
taken in accordance with Standard RS-191.
HIGH VOLTAGE - The 4CX250B/M operates at voltages which
can be deadly, and the equipment must be designed properly
and operating precautions must be followed. Equipment must
be designed so that no one can come in contact with high volt-
ages. All equipment must include safety enclosures for high-
voltage circuits and terminals, with interlock switches to open
the primary circuits of the power supplies and to discharge
high-voltage condensers whenever access doors are opened.
Interlock switches must not be bypassed or “cheated” to allow
operation with access doors open. Always remember that HIGH
VOLTAGE CAN KILL.
The equipment designer is therefore cautioned to make allow-
ance for the actual capacitance values which will exist in any
normal application. Measurements should be taken with the
socket and mounting which represent approximate final layout
if capacitance values are highly significant in the design.
HOT SURFACES - Air-cooled surfaces and other parts of tubes
can reach temperatures of several hundred degrees C and
cause serious burns if touched for several minutes after all
power is removed.
SPECIAL APPLICATIONS - If it is desired to operate this tube
under conditions widely different from those given here, contact
the Application Engineering Dept., CPI MPP Eimac Operation,
Palo Alto, Calif. 94304 for information and recommendations.
OPERATING HAZARDS
Proper use and safe operating practices with respect to power tubes are the responsibility of equipment manufacturers and users
of such tubes. All persons who work with and are exposed to power tubes, or equipment that utilizes such tubes, must take precau-
tions to protect themselves against possible serious bodily injury. DO NOT BE CARELESS AROUND SUCH PRODUCTS.
The operation of this tube may involve the following hazards, any one of which, in the absence of safe operating practices and pre-
cautions, could result in serious harm to personnel.
HIGH VOLTAGE – Normal operating voltages can be deadly.
Remember the HIGH VOLTAGE CAN KILL.
HOT SURFACES – Surfaces of tubes can reach temperatures
of several hundred °C and cause serious burns if touched for
several minutes after all power is removed.
LOW-VOLTAGE HIGH-CURRENT CIRCUITS - Personal jewelry,
such as rings, should not be worn when working with filament
contacts or connectors as a short circuit can produce very high
current and melting, resulting in severe burns.
MATERIAL COMPLIANCE - This product and package conforms
to the conditions and limitations specified in 49CFR 173.424 for
radioactive material, excepted package-instruments or articles,
UN2910. In addition, this product and package contains no
beryllium oxide (BeO).
RF RADIATION – Exposure to strong rf fields should be avoided,
even at relatively low frequencies. CARDIAC PACEMAKERS
MAY BE AFFECTED.
Please review the detailed Operating Hazards sheet enclosed
with each tube, or request a copy from CPI MPP, Eimac Opera-
tion Application Engineering at 1-650-592-1221.
4
RADIAL BEAM POWER TETRODE
4CX250B/M
7203A
5
RADIAL BEAM POWER TETRODE
4CX250B/M
7203A
6
RADIAL BEAM POWER TETRODE
4CX250B/M
7203A
CPI 072011
7
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