RCA_8984_8985_8986_8988_BeamPowerTubes_1978

ELECT330~'IC INDUSTRIES t~iiSSOCI~TIO

2001 EYE STREET, N. W.

WASHINGTON. D. C. 20005

TELE°HONE: (202) 457-4900
CABLES: ELECTRON WASHINGTON DC

Correction Notice ~~a ,,~e~, .m`~a
of
.s~~..:',':xo' i ..5.~_.~.Ta~es'A
Electron Device Type Registration
Release No. 6734 '~° ~ T
~, L "~
May 30, 1978

The Joint Electron Device Engineering Council announced the registration
of the following electron device designation

8988

on April 18, 1978.

The data is now revised as follows:

ITEM AS REGISTERED AS CORRECTED

1/ Page 1, second paragraph, ...4.5 kW aural power ...5.0 kW aural power
output required fora output required for a
2/ General Data: Current 17.5 kW TV Xmitter. 25 kW TV transmitter.

Typical value at 5.7 V 115 V 115 A

3/ Direct Interelectrode 0.40 pf (max) 0.20 pf (max)
Capacitances: 70 pf 76 pf
Grid No. 1 to Plate 0.05 pf (max)
Grid No. 1 to Filament 0,02 pf (max)
Plate to Filament 95 pf 86 pf
Grid No. 1 to Grid No. 2 2.5 pf (max)
1.5 pf (max)
Grid No. 2 to Filament

Category 4

r

a + ~a pT~ ..

ELECTRONIC INDUSTRIES ASSOCIATION

2001 EYE STREET, N. W. TELEPHONE: (202) 457-4900
CABLES: ELECTRON WASHINGTON DC
WASHINGTON, D. C. 20006

Announcement

of .~,~~, ","
Electron Device Type Registration ,~.+a ~~ ~. ss
,~,,,,«,,tee .. ~,,^y a~. 1 rFa'~'

Release No. 6734 ~~~
April 18, 1978

The Joint Electron Device Engineering Council announces the registra-
tion of the following electron device designations

8984
8985
8986
8988

according to the ratings and characteristics found on the attached data

sheets on the application of

RCA Corporation
Lancaster, Pennsylvania

4



RCA ElectroOptics Power Tube
and Devices 8984

VHF Linear Beam Power Tube

■ Full Input to 300 MHz
Forced-Air Cooled

■ 55 kW Peak Sync. Output
VHF-TV Band
16 d6 Gain '

■ FM Broadcast Service
55 kW Output
16 d6 Gain

The RCA 8984 is designed specifically for use in high-gain, General Data J 14.0 typ. V
high-linearity equipments for VHF-TV and FM service. l 15.0 max. V
Electrical:
Rated for full input to 300 MHz, the tube is easily circuited Filamentary Cathode, Thoriated- 170 A
to this frequency. The terminals are coaxial for operation Tungsten Mesh Type:
in the TEM mode and the radiator location avoids restricting 350 max. A
the resonant cavity circuits in VHF operation. This assures Voltages (AC or DC) 0.01
high gain-bandwidth products for the full VHF -TV band. 120 S2
In addition, it is well suited for other applications such as Current:b
single sideband, CW or pulsed RF, modulator service, and Typical 15 s
translator service. Instantaneous peak value
during startups: 0.7 pF
Its sturdy, coaxial CERMOLOX construction and thoriated- 200 pF
tungsten mesh filament minimize tube inductances and Cold resistance 0.5 pF
feed-thru capacitances. They make possible the use of Minimum heating timec 250 pF
simple, economical, broadband circuit techniques in VHF Mu-Factord (Grid No.2 to Grid No.1)
operation. Additional information of a general nature Direct Interelectrode Capacitances: 30 pF
applicable to tubes of this type is given in the following Grid No.1 to plates 5 pF
publications: Grid No.1 to filament
Plate to filaments Vertical, anode up
1CE-279A Application Guide for RCA Large Power Tubes Grid No.1 to grid No.2
1CE-300 Application Guide for RCA Power Tubes Grid No.2 to plate 11.3 in
AN-4020 Screen-Grid Current, Loading and Bleeder Grid No.2 to filaments
AN-4865 Handling and Operating Considerations 10.3 in
AN-4869 Application Guide for Forced Air Cooling Mechanical:
AN-4872 Broadcast-Tube Handling and Installation Operating Attitude Integral part of tube
Overall Length (Max.)
Close attention to the instructions contained in these publi- Greatest Diameter (Max.) 60 Ibs
cationswill assure longer tube life, safer operation, less Radiator
equipment downtime and fewer tube handling accidents. Weight (Approx.) 250 max. oC

Formerly RCA Type 4690. Thermal: 250 max. ~C
Seal Temperaturef
(Plate, Grid-No.2, Grid-No.t,
Cathode-Filament, and Filament)

Average Plate-Core Temperature9

For further nformation or application assistance on this device, contact your RCA Sales Representative or write Power Tube Marketing, RCA, Lancaster, PA 17604.

Information furnished by RCA is believed to be accurate and Trademark(:) Registered ~
reliable. However, no responsibility is assumed by RCA for
its use; nor for any infringements of patents or other rights of Marca(s) Registroda(s)
third parties which may result from its use. No license is
granted by implication or otherwise under any patent or Printed in U.S.A./2-78
patent rights of RCA. 8984

8984

RF Power Amplifier-Class B Television Serviceh RF Power Amplifier & Osc. -Class AB Telegraphy
and RF Power Amplifier -Class AB FM Telephonyh
Synchronizing-level conditions per tube unless otherwise specified.

Maximum CCS Ratings, Absolute-Maximum Values: Maximum CCS Ratings, Absolute-Maximum Values:

DC Plate Voltagel 15,000 max. V Up to 300 MHz

DC Grid-No.2 Voltagek 2000 max. V DC Plate Voltagel 15,000 max. V

DC Grid-No.1 Voltageq -600 max. V DC Grid-No.2 Voltagek 2000 max. V

DC Plate Current 12 max. A DC Grid-No.t Voltageq -600 max. V

Plate Dissipationm 40,000 max. W DC Plate Current 12 max. A

Grid-No.2lnput 500 max. W Grid-No.1 Input 300 max. W

Grid-No.1 Input 300 max. W Grid-No.2lnput 500 max. W

Pfate Dissipationm 40,000 max. W

Typical CCS Operation: Maximum Circuit Values:
In a cathode-drive circuit at 216 MHz and bandwidth of 6.3 MHzr
Grid-No.l-Circuit Resistance Under Any Conditions:

DC Plate Voltage 10,500 V With fixed bias 1000 max. S2

DC Grid-No.2 Voltage 1200 - V With cathode bias Not recommended

DC Grid-No.1 Voltagen -75 V Typical, Grid Driven, Class B, CCS Operation:

Zero-Signal DC Plate Current 1.5 A DC Plate Voltage ~ At 7.0 MHz
DC Grid-No.2 Voltage 10,000 V
DC Plate Current: DC Grid-No.1 Voltagen 1250 V
Zero-Signal DC Plate Current -95 V
Synchronizing level 8.4 A DC Plate Current 0.5 A
DC Grid-No.2 Current 8.4 A
Blanking level 6.4 A DC Grid-No.l Current 0.3 A
Driver Power Output IApprox.lp 1.1 A
DC Grid-No.2 Current: Grid Loading Resistance 200 W
Useful Power Output
Synchronizing level 0.3 A 750 SZ

Blanking level 0.1 A 55,000 W

DC Grid-No.1 Current:

Synchronizing level 0.25 A

Blanking level 0.12 A

Driver Power Output:p

Synchronizing level 1250 W Typical CCS Operation:
Blanking level 700 W In a Grid-Drive Circuit at 108 MHz
Useful Power Output: DC Plate Voltage
DC Grid-No.2 Voltage
Synchronizing level 55,000 W DC Grid-No.1 Voltage 10,800 V
Blanking level 30,800 W DC Plate Current 1300 V
Power Gain, Including Circuit Losses d6 DC Grid-No.2 Current -250 V
16.4 DC Grid-No.1 Current 6.5 A
Driver Power Output (Approx.lp 0.28 A
Useful Power Output 0.01 A
1400 W

55,000 W

a Measured at the tube terminals. For accurate data the ac fila- b It is recommended that additional current be available to allow
ment voltage should be measured using an accurate RMS type for both product variation and the normal reduction of filament
meter such as an iron-vane or the thermocouple type meter. resistance with life. Thus the filament supply adjustment should
The do voltage should be measured using a high input impedance be designed for capability of 205 amperes at 14.0 volts. A
type meter. minimum setting is 13.5 volts.

For high-current, low-voltage filaments such as are used in this c Recommended starting procedure for maximum stability and
tube, it is recommended that the filament current be monitored longest life.
since very small changes in resistance can produce misleading (1) Standard: Filament heating time of 120 seconds followed
changes in voltage. For maximum life, the filament power by grid-No.1, plate, grid-No.2, and rf drive.
should be regulated at the lowest value that will give stable
performance. For those applications where hum is a critical 12) Emergency: Filament heating time of 15 seconds followed
consideration, do filament or hum bucking circuits are recom-
mended. See also Application Note AN11865. by grid-No.1, plate, grid-No.2, and rf drive. In addition,
grid-No.1 voltage and rf drive must be changed proportion-
ally to reduce plate current to 75% of its normal value for
the first 15 seconds to prevent tripping plate overcurrent
devices.

2

8984

d For plate voltage = 2000 V, grid-No.2 voltage = 1250 V, and P Driver power output represents circuit losses in the driver out-
plate current = 15 A. put circuit and the grid input circuit in addition to the power

• e No external shield. necessary to drive the tube.

f See Dimensional Outline for Temperature Measurement Points. q See Section V.B.3 of 1CE-300. Protection devices such as spark
For good contact-finger life, a maximum temperature of 180o C gaps or positive clamping diodes should be used.

at the terminal is recommended when using commercially- r The bandwidth of 6.3 MHz is calculated at the —0.72 d6 power
available beryllium-copper socket contacts. points of a doubled-tuned output circuit using two times the
tube output capacity and a damping factor of ~5 as shown
9 The value of 250o C is the average of 4 readings taken 90o apart
around the anode core. No one reading may exceed 275o C. in Figure 2.

h See Section V.0 of 1CE-300. At the 3 d6 points, the maximum s Use an oscilliscope in system checkout. Systems such as auto-
recommended Q is 30. transformers, step transformers, shortable limiting resistors,
saturable reactors, or combinations thereof must be used.
1 See Section V.B and V.6.1 of 10E-300.

The maximum voltage ratings must be modified for operation 0.28 dB
at altitudes higher than sea level and for temperatures in excess
of 20o C in accordance with the curves of Figure 1. For altitude Ref. Levee
derating of the plate voltage, use the voltage difference between
o.zz d6

plate and grid No.2.

The maximum fault energy that can be dissipated within the 6 3 MHz
tube is approximately 100 joules. Therefore, the energy avail- Fp
ablefor ahigh-voltage arc or fault must be limited to this value
by means of current limiting resistors or fault-protection cir- 9iL5-38a5
cuitry such as spark gaps and electronic "crow bars". This is
especially important where high, stored energy and large capac-
itors are used. In typical 55 kW TV transmitters, the series
resistors used are:

Plate —Thirty ohm minimum is required in high capacitance Figure 2 — Bandwidth Characteristics
power supplies for video service.

t Grid No.2 —Fifty ohms minimum. Operating Considerations
Grid No.t —Fifty ohms.
For additional information see VI.B of 10E-279A, "Application Safety Precautions

Guide for RCA Large Power Tubes". Protection circuits serve a threefold purpose: safety of

personnel, protection of the tube in the event of abnormal

—;++ circuit operation, and protection of the tube circuits in the
~. event of abnormal tube operation.

Z

o ,00 ~~ I~ Warning —Personal Safety Hazards

r t Electrical Shock —Operating voltages applied to this
z device present a shock hazard.

U X-Ray Warning —This device in operation produces
X-rays which can constitute a health hazard unless
so the device is adequately shielded for radiation.

Q RF Radiation —This device in operation produces rf
radiation which may be harmful to personnel.
0
o ao

a zo i

0 5 10 15 Power tubes require mechanical protective devices such as
ALTITUDE -THOUSAND FEET
92L6-4596 interlocks, relays, and circuit breakers. Circuit breakers

Figure 1 —Maximum DC Voltage with Respect to Altitude alone may not provide adequate protection in certain power-
tube circuits when the power-supply filter, modulator, or
k See Section V.8.2 of 1CE-300 and AN~020. Protection devices pulse-forming network stores much energy. Additional
such as spark gaps should be used. protection may be achieved by the use of high-speed elec-
tronic circuits to bypass the fault current until mechanical
m Permitted plate dissipation is a function of cooling. For specific circuit breakers are opened. These circuits may employ a
ratings see Forced Air Cooling information in this data sheet. controlled gas tube, such as a thyratron or ignitron, depend-
ing on the amount of energy to be handled.
n Adjusted for specified zero-signal do plate current.

3

8984

Great care should be taken during the adjustment of circuits. mance degradation such as a decrease in plate current
The tube and its associated apparatus, especially all parts or power output is noted. Then increase the heater
which may be at high potential above ground, should be voltage 0.2 volt above this point. Typically depending
housed in a protective enclosure. The protective housing upon the application, this voltage will be in the range
should be designed with interlocks so that personnel can of 13.8 to 14.2 volts.
not possibly come in contact with any high-potential point
in the electrical system. The interlock devices should During life when evidence is observed that a tube is be-
function to break the primary circuit of the high-voltage coming emission limited, increasing the filament voltage
supplies and discharge high-voltage capacitors when any may extend the useful life of the tube. However, never
gate or door on the protective housing is opened, and increase filament voltage to compensate for a decrease in
should prevent the closing of this primary circuit until the other circuit parameters such as rf drive or video modulating
door is again locked. voltage!

The screen circuit requires special attention because the Forced Air Cooling
heating power of the current and voltage on this electrode Cooling air flow is necessary to limit the anode-core and
is not the algebraic product of the current and voltage terminal-seal temperatures to values that will assure long
elements as observed at the terminal. For analysis of the reliable life. A sufficient quantity of air should be directed
circuit, review AN-4020. past each of these terminals so that its temperature does
not approach the absolute-maximum limit. The absolute-
A time-delay relay must be provided in the grid-No.1 maximum temperature rating for this tube is 275 C with a
supply circuit to delay application of this voltage until the maximum average temperature around the anode of 250 C.
filament has reached normal operating temperature. It is recommended that a safety factor of 25o to 50o be
applied, to compensate for all probable system and com-
An interlocking relay system should be provided to prevent ponent variations throughout life.
application of plate voltage prior to the application of suf-
ficient bias voltage otherwise, with insufficient bias, the The cooling air must be delivered by the blower through
resultant high plate current may cause excessive plate dissi- the radiator and at the terminal seals during the application
pation with consequent damage to the tube. R F load shorts of power and for a minimum of three minutes after the
or other causes of high output VSWR may also cause high power has been removed.
dissipations, excessive voltage gradients, or insulator flash-
over. The load VSWR should be monitored and the de- To Cathode-Filament and Filament Terminals—A sufficient
tected signal used to actuate the interlock system to remove quantity of air should be blown directly at these terminals
the plate voltage in less than 10 milliseconds after the fault so that their temperature does not approach the absolute-
occurs. maximum limit of 250o C. A value of at least 100 cfm is
recommended.
Filament-Voltage Adjustment
The fife of the filament can be conserved by adjusting to The Cooling Characteristic Curve indicates the air flow and
the lowest filament supply voltage that will give the desired pressure requirements of a system sufficient to limit the
performance. Follow the filament voltage adjustment core temperature to specific values for various levels of
procedure below. plate dissipation.

1. Before the application of any other voltages to a new Incoming air is at Standard Temperature and Pressure
tube, the filament voltage should be adjusted to 14.2 (STP) (22.5 C and 760 mm Hg►. Pressure drop values are
volts at the tube socket. A true RMS voltmeter should for the anode only and do not include any losses which
be used for accurate measurement. It may be more may occur with specific sockets or cavities. When the tube
convenient to make the measurement at other contacts base is not directly in the anode cooling air stream, special
in the equipment, but the value will be higher because provisions must be made for separate base cooling.
of increased impedance such as wire loss or contact
resistance. Because the cooling capacity of air varies with its density,
factors must be applied to the air flow to compensate for
2. Apply voltages and adjust tuning controls as necessary operation at altitude or in high temperature environments.
for proper operation as described in the appropriate
instruction manual. During Standby Operation —Cooling air is required when
only the filament voltage is applied to the tube.
3. Reduce the filament voltage in 0.1-volt increments—
repeating the procedures in Steps 1 and 2—until perfor- For further information on forced air cooling, see Section
IV.0 of 10E-300 and also AN-4869 "Application Guide for
Forced Air Cooling of RCA Power Tubes".

4

8984

CURVE PLATE DISSIPATION -WATTS DIRECTION OF AIR FLOW FILAMENT VOLTAGE E} = 14.0 V
GRID No.2 VOLTAGE EC2 = 1000 V
• A 40.000 PLATE CURRENT Ib =
B 35.000 GRID No.t CURRENT IC7 =---
C 30,000 GRID No.2 CURRENT IC2 =
D 25,000

E 20,000

F 15,000

G0 ■.■■■■. Q ■■■■■■■■■...■..■■■■...■.■■...../■.■
■.■.■■.N ■■....■ ■...■■..■■...■■■.■■■■\..■.
■....■. ~ ■■■h■■■.....■■.■.■■.■■.■..■■■■.■■■■
■.■... N .■..............■■■■.....■.■■....■■■
AIR FLOW/CORE TEMP 120 ■■■■.■ vh ■■fi■■■■■■■■■■...■...■.N....M.■■...
AIR FLOWlPRESS DROP — — —
MEASUREMENTSIN ACCORDANCE WITH ■....' —~:G--GG'~37--- GG 2 ii --- G■....

STANDARD TEST CODE FOR AIR MOVING INCOMING AIR - STP 100

DEVICES
AMCA STANDARD 210-67.

,200 IililDii::::~:::~~n:17::=~~ N~
' ~r inii~~~,..;. ...~.......-..GG"~CS"'-S - CG-- 37--- 23' - ~G..
i1000 ...~~..N■■.
\..■l~1 ... ~././h '1■■■■.■■■■.
f
60
600
111111 ~~....:::~:..::~~::::~.::::::C.~~.:
400
1■.1■1■1■1I ~u~~Xu1v1,■1.1.~1/.111111111111111Dwi.1w11111M1■1~11■1■111

N 20■.■■■I~iii►',1111i11111iillllllll~liitglli~
Ct Iliii!~!!~I~~IIIiIII11iiNNiq~N
W

AIR FLOW -CUBIC FEET PER Q

~ -20
0 I~tN~~~riliiiiilliliuiliiiNi~Niil
2 -40 ■..../1 i■t......~u~~N.■MrY ■19.

i111i~1~1i11i11111i11i11iliiiiillli'I ig.N■I
1■.1.1.1.r1.:.:.N.~..~.~.~!~.■~■~..I.II.I.II.I■II.I.I~Iua.lu■a1a1..■m■■ 1

lilii`iiitiliiliinilliiillilMlli!lNiilii
IiINllillfiliililiiiii" nnilneil~'
100.i.i.i.i.i.u..i■ii.i.iiiiiii~..i.i.i.i.i.i.i.i.i..i.i.i.i.i.i.l■iii.i.i. °0.52

--- ..■■■■\■■N.■. 0.05
~~.Bti■.. 0 02
120

-140

100 150 200 250 345 6 8
PLATE VOLTAGE —KILOVOLTS 9TLM-5263R/
AVERAGE CORE TEMPERATURE -°C

0 2.5 5.0 7.5 10.0 12.5 15.0

PRESSURE DROP -INCHES H2O BTLM-5262

Figure 3 — Typical Cooling Characteristics Figure 4 — Typical Constant Current Characteristics

•

5

8984

FILAMENT VOLTAGE Et= 14.0 V 25
GRID No.2 VOLTAGE EC2 = 1500 V —PLATE IPI TO GRID Not (G2
PLATE CURRENT ly=
GRID No.1 Current ICI = _ _ 20

GRID No.2 CURRENT IC2 =

... C2=2.OA 16A 1 2 A 0 6 A , ~ .,~ 15
!! C, ` 8A
10
100 •I~i~~
~` te._ ~ 6
>~ r I~ ~ 6A

.1\~„~V~~~~~~~.. -~ Ib=50A

ii! is i~~►l~ii~ii~1~'~:1~~ '7. 45A
~r~~ii~ ,~ 40A
~...r A ~ 0
—GRID Not (G2) TO GRID No.1 (G,1
'~~~ 0.4 A! G2
25 G1
40 ~~r~111~1t1►/1lAI i II~'35A
at20 w 20 5.00 O.D. Z
25A 2 L
.,A 2
6.00 I.D.Z
N J Za =10.90HMS

u~!a~Nli; milJ fC7 y
A Zy j 10
3
~ 20

Q 'I
' ~,t~
SA

0

a -~0 n~~i►: ~~ ~~~ ,~ t0A G5
zo INllaili~!~,~il~~~I1liil~iiIiliii.~_■
~ -60 I U

5A a
2.5 - GRID No.1 (Gt) TO CATHODE K)

-,00 Iu~n~nirU~►si~~l~~~~~f~~~n:■!n 25 G,
,20 K
i20
~~~I~n~lllill~~_. 4.12O.D.Z
15 4.87 I.D. Z
~n~~~~~nu~~! !i.!.1~.-140 Zo = 10.0 OHMS
Y
10 10 ~A .i~
0.5
02 m tC

.■.~.■w■_■■■~..__w~__a_■..... 0.1 5
-160 1~~~11~~iii~1~1~005
0.02

if 0 200 400 600 eoo
0 2 34 5 6 78
FREQUENCY -MHz
PLATE VOLTAGE -KILOVOLTS 92LM-526tR1 92LM-6246

Figure 5 — Typical Constant Current Characteristics Maximum rated frequency is 300 MHz. However, the tube is capable
of amplification to beyond 2 GHz and care must be taken by the
circuit designer to prevent parasitic oscillations at high frequencies.
Tuning curves above 300 MHz are provided for circuit design assis-
tance to prevent oscillation in the TES ~ mode.

Figure 6 — Electrode Cavity Tuning Characteristics

6

8984

:::NOTE 2

PLATE CORE TEMPERATURE
MEASUREMENT POINT
NOTE 3

PLATE
TERMINAL

GRID No.2 B
TERMINAL

GRID No.1
TERMINAL

CATHODE-FILAMENT- - p ~...
TERMINAL
N
FILAMENT t
TERMINAL
F~~ :~ :~ :1 NOTE 2
• n CERAMIC INSULATION

Tabulated Dimensions ~ SEAL TEMPERATURE
MEASUREMENT POINT
Dim. Inches Millimeters Notes
.! AIR FLOW
A Dia. 10.175 ± .040 258.44 ± 1.02 1, 4 92LM~5266R1
B Dia. 5.590 ± .020 141.97 ± .51 1, 4
C Dia. 4.590 ± ,020 116.59 ± .51 1, 4 Note 1 —The diameter of each terminal is maintained only over the
D Dia. 3.590 ± ,020 1, 4 indicated minimum length of its contact surface.
E Dia. 91.19 ± .51 1, 4
F Dia. 2.600 ± .010 66.04 ± .25 1, 4 Note 2 — Keep all stippled regions clear. In general do not allow
G 2.100 ± .010 53.34 ± .25 contacts to protrude into these annular regions. If special
H 11.300 max. 287.02 max. connectors are required which may intrude on these
J 10.500 max. 266.70 max. regions, contact RCA Power Tube Application Engineering,
K 4.075 ± .100 103.51 ± 2,54 Lancaster, PA 17604.
M 1.430 ± .060 36.32 ± 1.52
N 19.05 ± 1.52 Note 3 — Plate core temperature measurement point is located on
P .750 ± .060 the plate itself and not at the fins.
.710 ± .030 18.03 ± .76
.500 min. 12.70 min. Note 4 — With the plate terminal and the cathode-filament terminal
used as reference, the other terminals will measure less
Q .400 min. 10.16 min. than 0.060 (1.52 mm) total indicator runout (TIR).

Dimensions are in inches unless otherwise stated. Metric dimensions
are derived from the basic inch dimensions (One inch = 25.4
millimetersl.

R 3.650 ref. 92.71 ref.

Figure 7 — Dimensional Outline

7

8984

•

0

ncn ~

RCA~Solid State Division~Electro Optics and Devices~Lancaster, PA 17604

RCJI ElectroOptics Power Tube
and Devices 8985
Beam Power Tube

■ FM Broadcast Service
25 kW Output
20 dB Gain
80% Efficiency

■ High Efficiency-Low Pressure Radiator

The RCA 8985 is designed specifically for use in high-gain, Close attention to the instructions contained in these
high-efficiency FM service. publications will assure longer tube life, safer operation,
less equipment downtime and fewer tube handling acci-
Rated for full input to 230 MHz, the tube is easily circuited dents. For copies of these publications, specific information
to this frequency. The terminals are coaxial for operation or application assistance, contact your nearest RCA Repre-
in the TEM mode and the radiator location avoids restriction sentative or write RCA, New Holland Avenue, Lancaster,
of the resonant cavity circuits in VHF operation. PA 17604.
Its sturdy, coaxial construction and thoriated-tungsten mesh
filament minimize tube inductances and feed-thru capaci- Typical data was measured in the simple, economical
tances. They make possible the use of simple, economical, circuit cavity illustrated in Figure 5. Prototype or pro-
broadband circuit techniques in VHF operation. duction cavity assistance is available.

This data sheet gives application information unique General Data
to the RCA-8985. It is to be used in conjunction
with the publication, "Application Guide for RCA Electrical:
Power Tubes", 10E-300, for general application
information for tubes of this type. All voltages referenced to cathode, unless otherwise specified.

Additional information of a general nature applicable to Filamentary Cathode, Thoriated-
tubes of this type is given in the following publications: Tungsten Mesh Type:

10E-279A Application Guide for RCA Large Power Tubes Voltages lac or dc) 9.5 typ. V
AN-4020 Screen-Grid Current, Loading and Bleeder Current:
110.0 max. V
Considerations
AN-4865 Handling and Operating Considerations when Typical value at 9.5 voltsb 140 A

Using RCA Tetrodes Maximum value for starting, 300 A
AN-4869 Application Guide for Forced Air Cooling even, momentarily ~ 0.01
S2
RCA Power Tubes Cold resistance
AN-4872 Broadcast-Tube Handling and Installation
Recommended heating timec 2 min.
Instructions. Mu-Factord, (Grid No.2 to grid No.1) 12

Direct Interelectrode Capacitances: 0.65 pF
Grid No.1 to plates

Grid No.1 to filament 78 pF

Plate to filaments 0.09 pF
Grid No.l to grid No.2 89 pF
Grid No.2 to plate 17 pF

Grid No.2 to filamentf 3.7 pF

Far further information or application assistance on this device, contact your RCA Sales Representative orwrite Power Marketing, RCA, Lancaster, PA 17604.

Information furnished by RCA is believed to he accurate and Trademark lsl Reg~stered~
Marca(sl Reg~stradals)
reliable. However, no responsibility is assumed by RCA far
its use; nor for any infringements of patents or other rights of Printed in U.S.A./3.78
third parties which may result from its use. No license is
granted by implication or otherwise under any patent or RA Rai
Oatent riphta nt RCA

8985 -

General Data (Cont'd) Vertical, anode up b It is recommended that additional current be available to allow
(210.82 mm) 8.3 in for both product variation and the normal reduction of filament
Mechanical: (210.82 mm) 8.3 in resistance with life. Thus the filament supply adjustment should
Operating Attitude CD89-0858 or equivalent be designed for a capability of 167 amperes at 9.5 volts. A
Overall Length (Max.) Integral part of tube minimum setting is 8.85 volts.
Greatest Diameter
Socket (10 kg) 22 Ibs c Recommended starting procedure for maximum stability and
Radiator longest life:
Weight (Approx.) 250 max. oC Standard: Filament heating time of 2 minutes followed by grid-
No.1,plate, grid-No.2, and rf drive.
Thermal: 250 max. oC
Seal Temperatureh Emergency: Filament heating time of 1!i seconds followed by
(Plate, Grid No.2, Grid No.1, grid-No.1, plate, grid-No.2, and rf drive.
Cathode-Filament, and Filament)
Plate-Core Temperatureh d For plate voltage = 2000 V, grid-No.2 voltage = 1000 V, and
plate current = 5 A.
RF Power Amplifier —Class C, FM Telephony
e With external flat metal shield 8" (200 min) in diameter having a
Maximum CCS Ratings, Absolute-Maximum Values: center hole 3'" (76 mm) in diameter. Shield is located in plane
of the grid-No.2 terminal, perpendicular to the tube axis, and is
Up to 150 MHz connected to grid No.2.

DC Plate Voltage) 13,000 max. V f With external flat metal shield 8" (200 mm) in diameter having a
center hold 2.3/8" (60 mm) in diameter. Shield is located in
plane of the grid-No.1 terminal, perpendicular to the tube axis,
and is connected to grid No.1.

DC Grid-No.2 Voltagek 2000 max. V 9 As manufactured by: Jettron Products Inc.
56 Route Ten
DC Grid-No.1 Voltagep —600 max. V Hanover, NJ 07936

DC Plate Current 5 max. A

DC Grid-No.l Current 0.3 max. A h See Dimensional Outline for Temperature Measurement Points.
For good contact-finger life, a maximum temperature of 180° C
Grid-No.1 Input 150 max. W at the terminal is recormended when using commercially-
available beryllium-copper socket contacts.
Grid-No.2 Input 350 max. W
r
Plate Dissipationm 17,500 max. W

Grid Driven, Class C, CCS Operation: 9000 V ~N~~~~~~~~ ~~~~~N~~~~~~~~~~~/~~~~~~~~ ■ ■
Typical Data at 108 MHz 1200 V
DC Plate Voltage —450 V v
DC Grid-No.2 Voltage
DC Grid-No.1 Voltage 3.5 A a ~~~ c
DC Plate Current 0.15 A I
DC Grid-No.2 Current 0.05 A c too
DC Grid-No.1 Current 237 W z
Driver Power Output 25,200 W U
Useful Power Output
Overall Plate Eff 80 °~ 80
Gain 20.3 dB
i

~ so r---r — r—
0 ~~a~~N ~~~

c ao
f
f
a zo

Note s 0 5 10 75
ALTITUDE -THOUSAND rEET
a Measured at the tube terminals. For accurate data the ac filament 93L5-45%
voltage should be measured using an accurate RMS type meter
such as an iron-vane or the thermocouple type meter. The do Figure 1 —Maximum DC Voltage with Respect to Altitude
voltage should be measured using a high input impedance type
meter. j See Section V.B and V. 8.1 of 10E-300.
The maximum voltage ratings must be modified for operation at
For high-current, low-voltage filaments such as are used in this altitudes higher than sea level and for temperatures in excess of
type, it is recommended that the filament current be monitored ZOo C in accordance with the curves of Figure 1. For altitude
since very small changes in resistance can produce misleading Berating of the plate voltage, use the voltage difference between
changes in voltage. For maximum life, the filament power should plate and grid No.2.
be regulated at the lowest value that will give stable performance. The fault energy dissipated within the tube during ahigh-voltage
For those applications where hum is a critical consideration, do arc or fault must be limited by resistors or fault protection
filament or hum-bucking circuits are recommended. See also
Application Note AN-4865.

2

8985

.v _ PLATE CURRENT Ib PLATE CURRENT Ib
200 viii w~~ GRID NO. 1CURRENT IC7~'~. GRID NO. 1 CURRENT IC7
GRID NO. 2 CURRENT IC2~ GRID N0.2 CURRENT Iqw r w
•nxY. FILAMENT VOLTAGE Ef' 8.5V FILAMENT VOLTAGE E{' 9.5V
GRID NO. 2 VOLTAGE EC2' 1000 GRID NO. 2 VOLTAGE EQ' 1200

IC7 5.0 .uii~i.Mi i~ii~~i.Y

,5o ilw~'~lu"ei~w:.p •.ueeullanu 11/lunuemnlmnn W

iiii. - _r _. Y r_i r, W~i=L~~ ~i - _i_a _- Ib' 20.0 A

YY. .I..I.~.WYIY.NYNN~YN;A~S~~~>>- iiN

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0 .YY'w$ s. _--~.~.Y~w~w~rYwr~YY~Y~~~~01Y~..".~.Y~.~...w.YYwY

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wY Y.,.YY.
YY.p M~Y.YY...... w
GRID NO. 7 VOLTAGE -VOLTS
~Y 'i.isi=w.

,Y~YY.n;I...;
iai1~wws"~r~ri~nnriilllieieui:in~lI=i1::1:a1~~~IsI.wY1..a..1_w_n1an11i~~INN~ili
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. ' Yy.YN. Y.N

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~.~ YY.YY N.Y.Y

wlluulsii :ll!m.'.Mi~l~l,~■~11I~•1nI111wIpr -~l!1~1/~Y1IYIRIIIYI
' ' . ~i~19~iiiiil~~lllN~iffl~~~
YY.......YYY..Y..N..

300

~ 1~~~1l~l1~~~~~~~~~~~~~~~~~~~~

ii!~Ii~~il~iiiriiii~lilli~iliiAli~lillliifiiiil

350 ii~l~~~l~i~lli

-400 iil1~11.~.11.~.111111l1I1i1'1N111l1f1l 70 0 2 4 B 9 10
0 PLATEVOLTAGE~KILOVOLTS -
2468
PLATE VOLTAGE •KILOVOLTS 92LM-5707 f2LM-6708

Figure 2 — Typical Constant Current Characteristics Figure 3 — Typical Constant Current Characteristics

Notes (Cont'd) k See Section V.6.2 of 1CE-300 and AN-4020. Protection devices
such as spark gaps should be used.
circuitry such as spark gaps or electronic "crowbars". This is
especially important where large capacitors storing high energy m Permitted plate dissipation is a function of cooling. For specific
are used. The following current limiting resistance values are ratings see Forced-Air Cooling information in this data sheet.
recommended:
n Driver power output represents circuit losses in the grid input
Plate — 10 to 50 ohms circuit in addition to the power necessary to drive the tube.

• Grid No.2 — Fifty ohms minimum P See Section V.6.3 of 1CE-300. Protection devices such as spark
Grid No.1 — Fifty ohms minimum gaps or positive clamping diodes should be used.
For additional information see V1.6 of 10E-279A, "Application
Guide for RCA Large Power Tubes". q To limit filament surge current, a series resistor is recommended;
the resistor can then be shorted after 15 seconds.

3

898

Operating Considerations isAn interlocking relay system should be provided to prevent
application of plate voltage prior to the application of suf-
Safety Precautions ficient bias voltage otherwise, with insufficient bias, the
Protection circuits serve a threefold purpose: safety of resultant high plate current may cause excessive plate
personnel, protection of the tube in the event of abnormal dissipation with consequent damage to the tube. RF load
circuit operation, and protection of the tube circuits in the shorts or other causes of high output VSWR may also cause
event of abnormal tube operation. high dissipations, excessive voltage gradients, or insulator
flashover. The load VSWR should be monitored and the
Warning —Personal Safety Hazards detected signal used to actuate the interlock system to
remove the plate voltage in less than 10 milliseconds after
Electrical Shock —Operating voltages applied to this the fault occurs.
device present a shock hazard.
Filament-Voltage Adjustment
X-Ray Warning —This device in operation produces The life of the filament can be conserved by adjusting to
X-rays which can constitute a health hazard unless the lowest filament supply voltage that will give the desired
the device is adequately shielded for radiation. performance. Follow the filament voltage adjustment pro-
cedure below.
RF Radiation —This device in operation produces rf
radiation which may be harmfu► to personnel. Regulated Filament Supplies:
1. Before the application of any other voltages to a new
Power tubes require mechanical protective devices such as
interlocks, relays, and circuit breakers. Circuit breakers alone tube, the filament voltage should be adjusted to 9.5 volts
may not provide adequate protection in certain power-tube at the tube socket. A true RMS voltmeter should be used
circuits when the power-supply filter, modulator, or pulse- for accurate measurement. It may be more convenient
forming network stores much energy. Additional protection to make the measurement at other contacts in the equip-
may be achieved by the use of high-speed electronic circuits ment, but the value will be higher because of increased
to bypass the fault current until mechanical circuit breakers impedance such as wire loss or contact resistance.
are opened. These circuits may employ a controlled gas
tube, such as a thyratron or ignitron, depending on the 2. Apply voltages and adjust tuning controls as necessary
amount of energy to be handled. for proper operation as described in the appropriate
instruction manual.
Great care should be taken during the adjustment of circuits.
The tube and its associated apparatus, especially all parts 3. Reduce the filament voltage in 0.1 volt increments —
which may be at high potential above ground, should be repeating the procedures in Steps 1 and 2—until perfor-
housed in a protective enclosure. The protective housing mance degradation is noted. Then increase the heater
should be designed with interlocks so that personnel can voltage 0.1 volt above this point. Typically depending
not possibly come in contact with any high-potential point upon the application, this voltage will be in the range of
in the electrical system. The interlock devices should func- 9.2 to 9.5 volts.
tion to break the primary circuit of the high-voltage supplies
and discharge high-voltage capacitors when any gate or door Unregulated Filament Supplies:
on the protective housing is opened, and should prevent the 1. If an unregulated filament supply is used, the above
closing of this primary circuit until the door is again locked.
procedure for regulated supplies should be performed
The screen circuit requires special attention because the during low-line conditions to assure adequate tube per-
heating power of the current and voltage on this electrode formance during these periods. Then check during high-
is not the algebraic product of the current and voltage ele- line conditions to assure that the 10.0 volt maximum
ments as observed at the terminal. For analysis of the circuit, not exceeded.
review AN-4020.
During life when evidence is observed that a tube is becoming
A time-delay relay should be provided in the grid-No.1 supply emission limited, increasing the filament voltage may extend
circuit to delay application of this voltage until the filament the useful life of the tube. However, never increase filament
has reached normal operating temperature. voltage to compensate for a decrease in other circuit para-
meters such as rf drive or video modulating voltage!

4

8985

Tabulated Dimensions"

Dim. Inches Millimeters

A Dia.1 8.250 ± .040 209.55 ± 1.02

B Dia.1 3.028 ± .014 76.91 ± 0.36

C Dia.t 2.319 ± .012 58.90 ± 0.30

D Dia.1 1.850 ± .012 46.99 ± 0.30

E Dia.t 1.200 ± .010 30.48 ± 0.25

F 8.250 max. 209.55 max.

G 7.250 max. . 184.15 max.

PLATE CORE TEMPERATURE H 2.425 ± .100 61.60 ± 2.54
MEASUREMENT POINT
J 0.725 ± .040 18.42 ± 1.02

K 0.500 ± .030 12.70 ± 0.76

G M 0.200 ± .025 5.08 ± 0.64

N 0.220 min. 5.59 min.

P 0.250 min. 6.35 min.

Q 2.250 ref. 57.15 ref.

PLATE Q NOTE 2 • SEAL TEMPERATURE
TERMINAL CERAMIC INSULATION MEASUREMENT POINT

GRID N0.2 AIR FLOW
TERMINAL
e ~ -~ J>~ Note 1 —The diameter of each terminal is main-
GRID N0.1 c—~ tained only over the indicated minimum
TERMINAL length of its contact surface.
D~
Note 2 — Keep all stippled regions clear. In general,
CATHODE FILAMENT do not allow contacts to protrude into
TERMINAL these annular regions. If special con-
nectors are required which may intrude
FILAMENT on these regions contact RCA Power
TERMINAL Tube Applications Engineering,
Lancaster, PA.
92LM-5]09

Figure 4 — Dimensional Outline

r AIR OUT a,.
-o o f I)I I I I I I~I I I I I~I I I o

yxh,.,J.nR PLATE

~ BLOCKER &
TUNING
SHORT

RF OUTPUT Output Circuit Coaxial
3-t/8" COAX Zo 45 ohm
Circuit eff 98
uiul l i l i l l l lluunu 45
RSFtIQ
SCREEN 3.8 MHz
BLOCKER Cal. bandwidth: Strip Line plus Lumped Capacity
9 kV oper.
No Resistive Swamping
Input Circuit Grid Neutralized, Capacity Bridge

Neutralizing

~a~ , ~~—

I\ ~D~E IN 'Dimensions are in inches unless otherwise stated. Dimensions in
~~ TYPE N parentheses are in millimetres and are derived from the basic inch
CONNECTOR dimensions 11 inch = 25.4 mml.
\ Z~s~.wv+'rv,.c
92LM-5710
AIR IN

■ 7T" (SQUARE)

Figure 5 — Typical RF Circuit Cavity

5

8985

Forted Air Cooling CURVE PLATE DISSIPATION DIRECTION OF AIR FLOW
Cooling air flow Is necessary to limit the anode-core and WATTS
terminal-seal temperatures to values that will assure long INCOMING AIR TEMP. = 30'C
reliable Ilfe- A sufficient quantity of air should be directed A 17,500
past each of these terminals so that its temperature does not B 15,000 r,
approach the absolute-maximum limit. The absolute-maxi- I
mum temperature rating for this tube is 250o C. It is c 12,500
recommended that a safety factor of 25o to 50o be applied,
to compensate for all probable system and component varia- p 10.000
tions throughout life. E 7.500

The cooling air must be delivered by the blower through F0
the radiator and at the terminal seals during the application
of power and for a minimum of three minutes after the AIR FLOW/CORE TEMP
power has been removed. AIR FLOW/PRESS DROP- - -
NOTE: MEASUREMENTS IN ACCOR~
To Cathode•Filament and Filament Terminals — Asufficient
quantity of air should be blown directly at these terminals DANCE WITH STANDARD TEST
so that their temperature does not approach the absolute-
maximum limit of 250o C. A value of at least 60 cfm is CODE FOR AIR MOVING DEVICES.
recommended.
AMCA STANDARD 210-67.
The Cooling Characteristic Curve, Figure 6, indicates the air
flow and pressure requirements of a system sufficient to {II
limit the core temperature to specific values for various levels
of plate dissipation. 600 I i

Because the cooling capacity of air varies with its density, I
factors must be applied to the air flow to compensate for
operation at altitude or in high temperature environments. ~j

During Standby Operation —Cooling air is required when 500 I
only the filament voltage is applied to the tube.
AIR FLOW -CUBIC FEET PER MINUTE aoo r
For further information on forced air cooling, see Section ~' ti I
IV.0 of 1CE-300 and also AN-4869 "Application Guide for
Forced Air Cooling of RCA Power Tubes". f 6 E

300 I~N~M~t\~\~~ rY~
A~~MN~1 ~~ M
I

FI c
200 I

II
100 i r

I

0 100 200 300 aoo

CORE TEMPERATURE -'C

0 2 34 56

PRESSURE DROP -INCHES H2O 92LM-5711

Figure 6 — Air Flow Characteristics

RCA~Solid State Division~Electro Optics and Devices~Lancaster, PA 17604

RC/1ElectroOptics Power Tube
and Devices 898
Beam Power Tube

■ FM Broadcast Service
15 kW Output
20 d6 Gain
80% Efficiency

■ High Efficiency-Low Pressure Radiator

The RCA 8986 is designed specifically for use in high-gain, Close attention to the instructions contained in these

high-efficiency FM service. publications will assure longer tube life, safer operation,

Rated for full input to 150 MHz, the tube is easily circuited less equipment downtime and fewer tube handling acci-

to this frequency. The terminals are coaxial for operation dents. For copies of these publications, specific information

C in the TEM mode and the radiator location avoids restriction or application assistance, contact your nearest RCA Repre-
of the resonant cavity circuits in VHF operation. sentative or write RCA, New Holland Avenue, Lancaster,
PA 17604.

Its sturdy, coaxial construction and thoriated-tungsten mesh

filament minimize tube inductances and feed-thru capaci- Typical data was measured in the simple, economical

tances. They make possible the use of simple, economical, circuit cavity illustrated in Figure 5. Prototype or pro-

broadband circuit techniques in VHF operation. duction cavity assistance is available.

General Data

This data sheet gives application information unique Electrical:
to the RCA-8986. It is to be used in conjunction
with the publication, "Application Guide for RCA All voltages referenced to cathode, unless otherwise specified.
Power Tubes", 10E-300, for general application Filamentary Cathode, Thoriated-
information for tubes of this type. Tungsten Mesh Type:

Additional information of a general nature applicable to Voltages lac or dc) 9.5 typ. V
tubes of this type is given in the following publications:
Current: 10.0 max. V
1 CE-279A Application Guide for RCA Large Power Tubes
AN-4020 Screen-Grid Current, Loading and Bleeder Typical value at 9.5 voltsb 105 A
Maximum value for starting,
Considerations even, momentarilyq 220 A
AN-4865 Handling and Operating Considerations when Cold resistance 0.01
Recommended heating timec SZ
Using RCA Tetrodes Mu-Factord, (Grid No.2 to grid No.1) 2
AN-4869 Appl ication Guide for Forced Air Cooling 12 min.

RCA Power Tubes Direct Interelectrode Capacitances: 0.65 pF
AN-4872 Broadcast-Tube Handling and Installation Grid No.1 to plates 78 pF
Grid No.1 to filament pF
Instructions. Plate to filaments 0.09 pF
Grid No.t to grid No.2 89 pF
Grid No.2 to plate 17 pF
Grid No.2 to filamentf 3.7

For further information or application assistance on this device, contact your RCA Sales Representative or write Power Marketing, RCA, Lancaster, PA 17604.

Information furnished by RCA is believed to be accurate and Trademark lsl Registered ~

reliable. However, no responsibility is assumed by RCA for Marcalsl Regisiradalsl
its use; nor for any infringements of patents or other rights of
third parties which may result from its use. No license is Printed in U.S.A./3-78

granted by implication or otherwise under any patent or

8986

General Data (Cont'd) Vertical, anode up b It is recommended that additional current be available to allow
(199.39 mm) 7.85 in for both product variation and the normal reduction of filament
Mechanical: resistance with life. Thus the filament supply adjustment should
Operating Attitude (180.20 mm) 7.1 in be designed for a capability of 130 amperes at 9.5 volts. A
Overall Length (Max.) CD89-0859 or equivalent minimum setting is 8.85 volts.
Greatest Diameter
Socket Integral part of tube c Recommended starting procedure for maximum stability and
Radiator (5.5 kg) 12 Ibs longest life:
Weight (Approx.) Standard: Filament heating time of 2 minutes followed by grid-
250 max. oC No.1,plate, grid-tVo.2, and rf drive.
Thermal:
Seal Temperatureh 250 max. oC Emergency: Filament heating time of 15 seconds followed by
(Plate, Grid No.2, Grid No.1, grid-No.1, plate, grid-No.2, and rf drive.
Cathode-Filament, and Filament)
Plate-Core Temperatureh d For plate voltage = 2000 V, grid-No.2 voltage = 1000 V, and
plate current = 5 A.
RF Power Amplifier —Class C, FM Telephony
e With external flat metal shield 8" (200 mm) in diameter having a
center hole 3" 176 mm) in diameter. Shield is located in plane
of the grid-No.2 terminal, perpendicular to the tube axis, and is
connected to grid No.2.

Maximum CCS Ratings, Absolute-Maximum Values: f With external flat metal shield 8" (200 mm) in diameter having a
center hold 2-3 /8" (60 mm) in diameter. Shield is located in
Up to 150 MHz plane of the grid-No.1 terminal, perpendicular to the tube axis,
and is connected to grid No.1.
DC Plate Voltagei 13,000 max. V

DC Grid-No.2 Voltagek 1650 max. V 9 As manufactured by: Jettron Products Inc.
56 Route Ten
DC Grid-No.1 VoltageP —600 max. V Hanover, NJ 07936

DC Plate Current 3 max. A

DC Grid-No.1 Current 0.3 max. A h See Dimensional Outline for Temperature Measurement Points.
For good contact-finger life, a maximum temperature of 180o C
Grid-No.1 Input 100 max. W at the terminal is recommended when using commercially-
available beryllium-copper socket contacts.
Grid-No.2lnput 250 max. W

Plate Dissipationm 12,500 max. W

Grid Driven, Class C, CCS Operation: 9000 V z
Typical Data at 108 MHz 1000 V r
DC Plate Voltage —450 V
DC Grid-No.2 Voltage o too ~~_
DC Grid-No.t Voltage 2.1 A
DC Plate Current 0.10 A iniiiiiiiii~~iiiii~ii~iiii~iiiu~ii~iiiu~i
DC Grid-No.2 Current 0.06 A
135 W Iu111111111111ii1z?!N1111gf1im111N111111
DC Grid-No.1 Current 15,200 W iin~ivamie~~~N~ ;~n~u~ u~~ai~z
w ae
h 80 °~ U
20.5 d6 a ~:t~~~t~n~~~~~u~nn~~~~~~n.,,N ;~u~u~~
Driver Power Output so
w ~~~n~~w~~oNnn~~~~~~~~~~ u~ c ,a:~r~~~hu~•
Useful Power Output a
Overall Plate Eff
Gain r

0}
a

T

X0

Notes o s io 15

a Measured at the tube terminals. For accurate data the ac filament ALTITUDE -THOUSAND FEET
voltage should be measured using an accurate RMS type meter 92LS-9596
such as an iron-vane or the thermocouple type meter. The do
voltage should be measured using a high input impedance type Figure 1 —Maximum DC Voltage with Respect to Altitude
meter.
1 See Section V.B and V. 6.1 of ICE -300.
For high-current, low-voltage filaments such as are used in this
type, it is recommended that the filament current be monitored The maximum voltage ratings must be modified for operation at
since very small changes in resistance can produce misleading altitudes higher than sea level and for temperatures in excess of
changes in voltage. For maximum life, the filament power should 20° C in accordance with the curves of Figure 1. For altitude
be regulated at the lowest value that will give stable performance. Berating of the plate voltage, use the voltage difference between
For those applications where hum is a critical consideration, do plate and grid No.2.
filament or hum-bucking circuits are recommended. See also The fault energy dissipated within the tube during ahigh-voltage
Application Note AN-4865. arc or fault must be limited by resistors or fault protection

2

8986

' t ii. '1 PLATE CURRENT Iy PLATE CURRENT Ib

.00 Fi~ 0P GRID NO. 1 CURRENT ICt ~ ~-~ GRID NO. 1 CURRENT IC7~~—•
GRID NO. 2 CURRENT IC2~ GRID N0.2 CURRENT IC2~
FILAMENT VOLTAGE E} - 9.SV
FILAMENT VOLTAGE Ef = 9.SV GRID N0.2 VOLTAGE EC2 ~ 1000V
GRID NO. 2 VOLTAGE EC2 -BOON

' ~ ~G'1'tt•li°~.trtrsu~l- - IC - 5.OA '~

.~---r ~`~+ 6LQ1~It a.o ttttttttt

~~~~~~~

Ix ,~ ~ ta~ . — 3.0 Ih=150A
z.o
If ~t D5 t

~_-_--

tillti: _ :~:1111~

GAIL NU t VUL TALE Vt>l fS "iii

~.,t~t~ifl _-- i! illl~:~~ix~1n~u8t1i■itit~tttt~ttt.tt■t~toswtitstt.•t~e■t.t.~t'.--::tttt:tt:eetttttt~~
il1~IME~piMniiilll'

_ H~1 -- 111~~111~
«./I.~.~Y~i :- ~.awuu
1G0

`nl~i __ 1"`1r1ou 1111

2

i.~~~f.. IlCltttt t

150 .05
tttttttttt~ -= ~tt -- ~~"~'
.02

20C

r-250 .00uuuo. u..o.w..uuoo..w.x000w.au.wxox.uu.

-3W .r— ..... N.........Np.../........... M.... M..1.......N...n H........

-350

—Y

i t0 0 2 4 6 8 10

246 8 92LM-5706 PLATE VOLTAGE~KILOVOLTS 82LM~706

PLATE VOLTAGE -KILOVOLTS

Figure 2 — Typical Constant Current Characteristics Figure 3 — Typical Constant Current Characteristics

Notes (Cont'd1 k See Section V.6.2 of 1CE•300 and AN-4020. Protection devices
such as spark gaps should be used.
circuitry such as spark gaps or electronic "crowbars". This is
especially important where large capacitors storing high energy m Permitted plate dissipation is a function of cooling. For specific
are used. The following current limiting resistance values are ratings see Forced-Air Cooling information in this data sheet.
recommended:
n Driver power output represents circuit losses in the grid input
Plate — 10 to 50 ohms circuit in addition to the power necessary to drive the tube.
Grid No.2 — Fifty ohms minimum
Grid No.t — Fifty ohms minimum P See Section V.6.3 of 1CE-300. Protection devices such as spark
For additional information see VI.B of 1CE-279A, "Application gaps or positive clamping diodes should be used.
Guide for RCA Large Power Tubes".
To limit filament surge current, a series resistor is recommended;
the resistor can then be shorted after 15 seconds.

3

8536

Operating Considerations An interlocking relay system should be provided to prevent
application of plate voltage prior to the application of suf-
Safety Precautions ficient bias voltage otherwise, with insufficient bias, the
Protection circuits serve a threefold purpose: safety of resultant high plate current may cause excessive plate
;~rsonnel, protection of the tube in the event of abnormal dissipation with consequent damage to the tube. RF load
circuit operation, and protection of the tube circuits in the shorts or other causes of high output VSWR may also cause
•vent of abnormal tube operation. high dissipations, excessive voltage gradients, or insulator
flashover. The load VSWR should be monitored and the
Warning —Personal Safety Hazards detected signal used to actuate the interlock system to
remove the plate voltage in less than 10 milliseconds after
Electrical Shock —Operating voltages applied to this
Cevice present a shock hazard. the fault occurs.

X•Ray NJarning —This device in operation produces Filament-Voltage Adjustment
X~rays which can constitute a health hazard unless The life of the filament can be conserved by adjusting to
the device is adequately shielded for radiation. the lowest filament supply voltage that will give the desired
performance. Follow the filament voltage adjustment pro-
RF Radiation —This device in operation produces rf
radiation which may be harmful to personnel. cedure below.

Power tubes require mechanical protective devices such as Regulated Filament Supplies:
,nterlecks, relays, and circuit breakers. Circuit breakers alone 1. Before the application of any other voltages to a new
m_iy not provide adequate protection in certain power-tube
tube, the filament voltage should be adjusted to 9.5 volts
c;rcuits when the power-supply filter, modulator, or pulse- at the tube socket. A true RMS voltmeter should be used
tormmg network stores much energy. Additional protection for accurate measurement. It may be more convenient
may be achieved by the use of high-speed electronic circuits to make the measurement at other contacts in the equip-
to bypass the fault current until mechanical circuit breakers ment, but the value will be higher because of increased
are opened. These circuits may employ a controlled gas impedance such as wire loss or contact resistance.
tube, such as a thyratron or ignitron, depending on the
amount of energy to be handled. 2. Apply voltages and adjust tuning controls as necessary
for proper operatign as described in the appropriate
instruction manual.

Great care should be taken during the adjustment of circuits. 3. Reduce the filament voltage in 0.1 volt increments—
repeating the procedures in Steps 1 and 2—until perfor-
The tube and its associated apparatus, especially all parts mance degradation is noted. Then increase the heater
voltage 0.1 volt above this point. Typically depending
which may be at high potential above ground, should be upon the application, this voltage will be in the range of
9.2 to 9.5 volts.
housed in a protective enclosure. The protective housing
Unregulated Filament Supplies:
should be designed with interlocks so that personnel can 1. If an unregulated filament supply is used, the above
not possibly come in contact with any high-potential point
in the electrical system. The interlock devices should func- procedure for regulated supplies should be performed
tion to break the primary circuit of the high-voltage supplies during low-line conditions to assure adequate tube per-
and discharge high-voltage capacitors when any gate or door formance during these periods. Then check during high-
on the protective housing is opened, and should prevent the line conditions to assure that the 10.0 volt maximum is
closing of this primary circuit until the door is again locked. not exceeded.

The screen circuit requires special attention because the During life when evidence is observed that a tube is becoming
heating power of the current and voltage on this electrode emission limited, increasing the filament voltage may extend
is not the algebraic product of the current and voltage ele- the useful life of the tube. However, never increase filament
ments as observed at the terminal. For analysis of the circuit, voltage to compensate for a decrease in other circuit para-
review AN-4020. meters such as rf drive or video modulating voltage!

A time-delay relay should be provided in the grid-No.l supply
circuit to delay application of this voltage until the filament
has reached normal operating temperature.

4

8986

NOTE2 Tabulated Dimensions*

~ >:~: Dim. Inches Millimeters
A Dia.t
PLATE CORE TEMPERATURE G B Dia.t 7.055 ± .040 179.20 ± 1.02
C Dia.1 3.028 ± .014 76.91 ± 0.36
MEASUREMENT POINT , ► D Dia.1 2.319 ± .012 58.90 ± 0.30
~ .E Dia.1 1.850 ± .012 46.99 ± 0.30
PLATE ....................................... F 1.200 ± .010 30.48 ± 0.25
TERMINAL I1 G 7.850 max.
H 7.250 max. 199.39 max.
} J 2.425 ± .100 184.15 max.
K 0.725 ± .040
92LM-570G M 0.500 ± .030 61.60 ± 2.54
N 0.200 ± .025 18.42 ± 1.02
P 0.220 min. 12.70 ± 0.76
O 2.250 ref.
R Dia. 1.500 ref. 5.08 ± 0.64
S 2.975 ref. 5.59 min.
0.250 min. 57.15 ref.
38.10 ref.
75.56 ref.
6.35 min.

N Q NOTE 2 • SEAL TEMPERATURE
M MEASUREMENT POINT
1 I CERAMIC INSULATION
AIR FLOW

B-~ Note 1 -The diameter of each terminal is main-
tained only over the indicated minimum
GRID N0.2 K
TERMINAL length of its contact surface.

GRID NO. t Note 2 - Keep all stippled regions clear. In general,
TERMINAL do not allow contacts to protrude into
these annular regions. If special con-
CATHODE FILAMENT E --~ nectorsare required which may intrude
TERMINAL on these regions contact RCA Power
FILAMENT Tube Applications Engineering,
TERMINAL

Figure 4 - Dimensional Outline Lancaster, PA.

V` AIR OUT
~ I I~I I I I I I~I I I I I~I I l a

K iM s PLATE
7 BLOCKER &
c ,rt.~?rF TUNING
SHORT

28" Output Circuit Coaxial
Zo 45 ohm
~uul i i i i i l i l i t iuiuu RF OUTPUT Circuit eff 98
3~ti8"COAX Rsh/O 45
Cal. bandwidth:
/ 9 kV oper 2.3 MHz
\r~ Strip Line plus Lumped Capacity
Input Circuit
GREEN No Resistive Swamping
BLOCKER Neutralizing Grid Neutralized, Capacity Bridge

11°! I'I DRIVE IN *Dimensions are in inches unless otherwise stated. Dimensions in
L_~~ TYPE N parentheses are in millimetres and are derived from the basic inch
CONNECTOR
~ ', ~ ~-- dimension 11 inch = 25.4 mm).
92LM-5710
L ~~

~rtv~.rrnnoc
AIR IN

17" (SQUARE)

Figure 5 -Typical RF Circuit Cavity

5

8986

Forced Air Cooling CURVE PLATE DISSIPATION DIflECTION OF AIR FLOW
Cooling air flow is necessary to limit the anode-core and WATTS NCOMING AIR TEMP.~ 3k1'C
terminal-seal temperatures to values that will assure long A
reliable life. A sufficient quantity of air should be directed B i25oo
past each of these terminals so that its temperature does not
approach the absolute-maximum limit. The absolute-maxi- c 10000
mum temperature rating for this tube is 250o C. It is
recommended that a safety factor of 25o to 50o be applied, D 7500
to compensate for all probable system and component varia- E
tions throughout life. 5000

The cooling air must be delivered by the blower through 0
the radiator and at the terminal seals during the application
of power and for a minimum of three minutes after the 700 AIR FLOW/CORE TEMP
power has been removed. AIR FLOW/PRESS DROP
NOTE: MEASUREMENTS IN ACCOR-
To Cathode-Filament and Filament Terminals - Asufficient DANCE WITH STANDARD TEST
quantity of air should be blown directly at these terminals CODE FOR AIR MOVING DEVICES
so that their temperature does not approach the absolute- AMCA STANDARD 210-67.
maximumlimit of 250o C. A value of at least 60 cfm is
recommended. soo

The Cooling Characteristic Curve, Figure 6, indicates the air t✓
flow and pressure requirements of a system sufficient to
limit the core temperature to specific values for various levels 500
of plate dissipation.
AIR FLOW -CUBIC FEET PER MINUTE f
Because the cooling capacity of air varies with its density,
factors must be applied to the air flow to compensate for 1aoo
operation at altitude or in high temperature environments.
~~
During Standby Operation —Cooling air is required when A
only the filament voltage is applied to the tube.
E i s
For further information on forced air cooling, see Section
IV.0 of 1CE-300 and also AN-4869 "Application Guide for zoo Dc
Forced Air Cooling of RCA Power Tubes".
iw

o goo zoo soo noo

CORE TEMPERATURE -'C 82LM-6703

0 12 34 58

PRESSURE DROP -INCHES H2O

Figure 6 — Air Flow Characteristics

RCA~Solid State Division~Electro Optics and DeviceslLancaster, PA 17604

nc~ ElectroOptics Power Tube
and Devices 8988

Linear Beam Power Tube

■ CERMOLOX® Tube

■ High Gain-Bandwidth Products

■ Full Input to 400 MHz
■ 7000 W Peak Sync. Output Through

VHF-TV Band with 16 dB Gain

The RCA 8988 is designed specifically to meet the Fligh AN-4865 Handling and Operating Considerations
linearity, high gain requirements of modern, reliable, VHF - AN-4869 Application Guide for Forced Air Cooling
TV and UHF linear amplifier equipments. AN-4872 Broadcast-Tube Handling and Installation
In VHF-TV service at 220 MHz, the 8988 will deliver a full
7.0 kW peak sync. output with 6.3 MHz bandwidth and 16 Close attention to the instructions contained in these publi-
cations will assure longer tube life, safer operation, less
d6 gain. At 220 MHz it can supply the 4.5 kW aural power equipment downtime and fewer tube handling accidents.
output required fora 17.5 kW TV transmitter. For copies of publications, specific information or applica-
tion assistance, contact your nearest RCA Representative
Rated for full input for the VHF-TV band and for other or write RCA, New Holland Avenue, Lancaster, PA 17604.
service to 400 MHz, the 8988 can be readily circuited for
these frequencies. The 8988 and available variants are also General Data Thoriated-Tungsten Mesh

well suited for other applications such as SSB, CW, pulsed Electrical: J 5.7 typ. V
RF, or modulator service. Filamentary Cathode: 6.0 max. V

Its sturdy, CERMOLOX construction and thoriated tungsten, Type 115 V
mesh filament minimize tube inductances and feedthru
capacitances. Its coaxial, forced-air-cooled radiator reduces Voltagea (ac or dc) 300 A
0.005
noise to a minimum and insures against spurious outputs. Current: S2
These features make possible the use of simple, economical, Typical value at 5.7 voltsb 15
Maximum value for starting s
broadband circuit techniques in VHF and UHf operation. even momentarily
20
This data sheet gives application information unique to Cold resistance
the RCA 8988. It is to be used in conjunction with the Minimum heating times 0.40 max. pF
publication, "Application Guide for RCA Power Tubes", Mu-Factor:d 70 pF
10E-300, for general application information for tubes (Grid No.2 to grid No.1) pF
of this type. Direct Interelectrode Capacitances: 0.05 ma.x pF
Grid No.1 to plates 95 pF
Additional information of a general nature applicable to Grid No.1 to filament 12 pF
tubes of this type is given in the following publications: Plate to filamente~f 2.5 max.
10E-279A Application Guide for RCA Large Power Tubes Grid No.1 to grid No.2
AN-4020 Screen-Grid Current, Loading and Bleeder Grid No.2 to plate
Grid No.2 to filamentf

For further information or application assistance on this device, contact your RCA Sales Representative or write Power Marketing, RCA, Lancaster, PA 17604.

O evelopmental~type devices or materials are intended for Information furnished by ACA is believed to be accurate and Trademark lsl Registered
engineering evaluation The type designation and data are Marcals) Registradals)
subject to change, unless otherwise arranged. No obligations reliable. However, no responsibility is assumed by flCA for
are assumed for notice of change or future manufacture of its use; nor for any infringements of patents or other rights of Printed in U.S.A./3-78
these devices or materials. third parties which may result from its use. No license is 8988
granted by implication or otherwise under any patent or

oat~ni rights of RCA.

8988

General Data (Cont'd) RF Power Amplifier or Oscillator -
Class B Telegraphy or FM Telephonyi
Mechanical:
Operating Attitude Vertical, either end up Maximum CCS Ratings, Absolute-Maximum Values
Overall Length (136.6 mm) 5.38 max. in
Greatest Diameter (116.1 mm) 4.57 max. in Up to 400 MHz
Terminal Connections
Socket See Dimensional Outline DC Plate Voltagek•m 8000 max. V
Chimney CD 89-0859, or equivalent
Radiator DC Grid-No.2 Voltagen 1650 max. V
Weight (Approx.) 88229, or equivalent DC Grid-No.1 VoltageP -450 max. V
Integral part of tube DC Plate Current
DC Grid-No.1 Current 4.0 max. A
(2.7 kg) 6.0 Ibs 500 max. mA

Grid-No.l Input 50 max. W

Thermal: Grid-No.2lnput 150 max. W

Seal Temperatureh (Plate, grid No.2, Plate Dissipation 5000 max. W
grid No.1,ftlament-cathode and
filament) Maximum Circuit Values:

Plate-Core Temperatureh 250 max. oC Grid-No.1 Circuit Resistance Under Any Conditions:
250 max. oC
With fixed bias 5000 max. SZ

With cathode bias Not recommended

Grid-No.2 Circuit Impedance See note n

Plate Circuit Impedance See note k

RF Power Amplifier -Class A62 Television Servicei

Synchronized-level conditions per tube unless otherwise specified

Maximum CCS Ratings, Absolute-Maximum Values:

DC Plate Voltagek•m 8000 max. V Notes

DC Grid-No.2 Voltagen 1650 max. V a Measured at the tube terminals. For accurate data the ac filament
voltage should be measured using an accurate RMS type meter
DC Grid-No.1 VoltageP -450 max. V such as an iron-vane or thermocouple type meter. The do voltage
should be measured using a high input impedance type meter.
DC Plate Current 5 max. A For high-current, low-voltage filaments such as are used in this
tube, it is recommended that the filament current be monitored,
Plate Dissipation 5000 max. W since very small changes in resistance can produce misleading
changes in voltage. For maximum life, the filament power should
Grid-No.2lnput 150 max. W be regulated at the lowest value that will give stable performance.
For those applications where hum is a critical consideration, do
Grid-No.1 Input 50 max. W filament orhum-bucking circuits are recommended. See also
Application Note AN-4865.
Typical CCS Operation:
b The characteristic range of current at 5.7 volts is from 106 to
In a cathode rive circuit at 216 MHz and a bandwidth of 6.3 MHzr 126 amperes. It is recommended that an additional six amperes
be available to allow for the normal reduction of filament resis-
DC Plate Voltage 3000 4100 V tance with life. Thus, the filament supply should be designed
for a mean value of 132 amperes at 5.7 volts.
DC Grid-No.2 Voltage 1000 1000 V
c Sequence for applying voltage is as follows: Filament, Bias,
DC Grid-No.1 Voltage -40s -28t V Plate, Screen and RF Drive.

Zero Signal DC Plate Current 0.4 0.8 A d For plate voltage = 2000 V, grid-No.2 voltage = 1375 V, and
plate current = 6.0 A.
DC Plate Current:
e With external flat metal shield 8" (200 mm) in diameter having a
Synchronizing level 1.3 2.3 A center hole 3" (76 mm) in diameter. Shield is located in plane
of the grid-No.2 terminal, perpendicular to the tube axis, and is
Blanking level 1.0 1.8 A connected to grid No.2.

DC Grid-No.2 Current: f With external flat metal shield 8" (200 mm) in diameter having
center hole 2-3/8" (60 mm) in diameter. Shield is located in
Synchronizing level - 100 mA plane of the grid-No.t terminal, perpendicular to the tube axis,
and is connected to grid No.1.
Blanking level 20 50 mA
9 As manufactured by Jettron Products Inc., 56 Route Ten,
DC Grid-No.1 Current: Hanover, NJ 07936.

Synchronizing level - 240 mA h See Dimensional Outline for Temperature Measurement points.

Blanking level 2.0 110 mA 1 See Section V.0 of 10E-300.

Driver Power Output: k See Section V. B and V.B.1 of 10E-300.

Synchronizing level 55 138 W

Blanking level 31 77 W

Plate Dissipation:

Blanking level - 4410 W

Output Circuit Efficiency 95 95 °~

Useful Power Output:

Synchronizing level 1700 5000 W

Blanking level 950 2820 W

2

8988 -

FILAMENT VOLTAGE E{ = 5.7 V FILAMENT VOLTAGE E{ = 5.7 V
GRID No. 2 VOLTAGE E~ = 1000 V
PLATE CURRENT Ip = GRID No. 2 VOLTAGE E~2 = 1500 V tttttttttttttttttttt
GRID No. 1 CURRENT 1c1 =
GRID No. 2 CURRENT 1~2 - PLATE CURRENT Ip =

200 GRID No. 1CURRENT I~t tttttttttttttttttttt
GRID No. 2 CURRENT 1c2 = tttttttttttttttttttt

tttttttttttttttttttt

tttttttttttttttttttt
ttttttttttttttt■/ttt
200 tttttttttttttttttttttttttttttttttttttttttttt

tttttttttttttttttttttNtttttttttt/ttttttttttt
ttttttttt\\ttttttttt■ttt■ttttttNtttttttttttt
ttttttttttp~~~tttttttttttNtttttNtttttttttttttttt
~n~nt~n~~tttttttt■ttt tttttttttt~ttttttt■tttttttttttttttttttttttt
ttttttttt\ tt■Ntttttttttttttttttttttttttttt
tttt...~
...150
750 NttNtr ::.:::r:~~:~
NttNttttNtt /tttttNt~ ~t1lttWtt■NttttttNttttttttttttttt
1 ■ttNtNtt ts~•fit
100 n11n~11f11 ■ tttt ttttL tt7ti ~~r\ Nt~t tt
ttttttttt/ Ottits tt~tto._ rtt 1e1 =3.OA ■tttttNttt
f N tto tN

50 ■~t~~ I~ = 3.0 A tttttttttn/~ttnNtt/tNtt//~~tir~i -rN
ttNttNtlltMtt?1~!Il~ttttttttttttttt~~■/rte_ tt
1 tttNNC\\tltlt7 tttttttNtttttttttttttNtt
0 ■■ tttttttt\~tYNt tttttNttNtttttttttttttNt

_50 Ip 12 A- 100 tttttttt\t~'1tFtt NttttttttN
tttttttttttttttttttttlttM/artwt7•■etutl.r~■rr:rr.~!_~rF:~t\ttNttttttttttttNttttrtNtrt't4lt~ott,~ttNttt-t't-- t
GRID No.l VOLTAGE —VOLTS ttttttttllt'tttt \ttttttttt
GRID No.1VOLTAGE —VOLTS
7raaNN
gtt~tttttt~~M!\ttttttttNtt
.w tttttNtN~ ~tlNYttttttttttNttttr~~!rtt~/~t

ttttt NCBItllMlti tNtttNtttttttttttttNtitYttt
tttttNtlw rI~IItLNttt Nttt ttttt ttttt tttN ttN
tttttttt A1A ~ItMttttttttttttttttttttttt~11tN
..►10 ttttttttH ANUNttttNt■tt/NtrtrrrrrN/L~t
ttttttttgit'tt7tNtttNttttttt tNtt NtgtNt
50 1 ~t ~A~tiattrNNNbNNtttttt\trN\\rt■N\rNrN ■tttNNN
tttttttf?t~
_ •~= 8 t tt tlN~tlNtttrrrNrN~~~a~~~~~_ Y
I

7 tttttttC~~l/~O~tHtB~gtnNttt ttttttttN ~ tt

0.~_ ~g tttttNlw~~=: ~~~~~a~arNrrNrNry~~tt

tttttttt tttttCtt~t/tltft►tl,Nlttt~tttNlt~ttNtlttN~tttt■t~~~~tttttttttttitt tt
I7~~~ttNtttl~tttttttt~.~~~tN
ttttttttll~./~Nt NN tt
0 tttttttt77l.N~i tNttNtttNttttttN ~ tt

~2 ttttttttttttt/t~r~~t/r.i.N~t --~•' ~~~ttttNtNttttttttttt tt
rarrrtttttttttttt
ttttttttt/INt V tttttttNtNttt tNtt tttNMtt
tttttttldHltti'~tttttttttttNtttttttt ttttttN
tttNttM /t~t~~tHNtNttNtttttt
z ttttttt/lN__._ _ _rrrrtt~iNtNtttttttNtp ~ttNNtt tt

~' tttNN/I Ar~t~tttttttNttNNtttttrrrNritt
0.2—^ ttttt tttMtttttttttt tt~t ttNt tNtt ttNtNtt
~-0.1"-' _5p ttttttp~f~Na~ ~~arNrrrtNN ■

tttNNc'~NtNttttttttt~tttNttHtt~ '
NttttNl~tttttlNtN NNraa~ ~t
tttttttLa ~rrtt~NtttttttNtttNttiWM
ttNttNNttttt -- -
tttttttrM=~~ a _r~
~f tttttttttttt~tttNttNttrNa~ -aN~N tttt ■
ttttttttt~aa
C-100 ■ttttttttttN tNtNA

-too

ttttt■ttttttNttttttttttttttttttttttttttttN

150 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~t~~
tttttttttttttttttttttttttttttttttttttttttttt
I
0 1 2 3 4 5 6 7 •8 150 ttttttttttNtttttttt■ttttttttttttttttttttttt

~~~~~n~~~~~~~~~~~\~~~~~~~~~~%~~~~~~~~~~~~~~
tttttttttttttttttttttttttttttttttttttttttttt
ttttttttttttttttttttttttttttttttttttttttttt■
0 2 3 4 5 B 7S

PLATE VOLTAGE -KILOVOLTS 92LM-3673

PLATE VOLTAGE -KILOVOLTS 92LM.387t

Figure 1 —Typical Constant Current Characteristics Figure 2 — Typical Constant Current Characteristics

m The maximum fault energy that can be dissipated within the tube s Adjusted for Ibo = 0.4 A. 0.28 d6
is approximately 100 joules. Therefore, the energy available for t Adjusted for Ibb = 0.8 A. Ref. Level-.~

a high-voltage arc or fault must be limited to this value by means r 63ti?Hz T a.n da
of current limiting resistors or fault-protection circuitry. This is T
r~
especially important in pulse service where high, stored energy Figure 3 — Bandwidth Calculation 92L5-"tA 45

and large capacitors are used. For typical 5000 watt TV trans-

mitters, series resistor values are:

Plate = 10 Sl
Screen = 30 to 50 S2
Grid = 50 Sl

For additional information see VI.B of ICE-279 "Application
Guide for RCA Large Power Tubes".

n See Section V.6.2 of 1CE-300.

P See Section V.6.3 of 1CE-300.

r The bandwidth of 6.3 MHz is calculated at the —0.72 d6 power

points of a double tuned output circuit using two times the tube

output capacity and a damping factor of ~ as shown in

Figure 3.

3

8988

Protection Circuits INCOMING AIR TEMPERATURE SW C DIRECTION OF AIR FLOW
Protection circuits serve a threefold purpose: safety of
personnel, protection of the tube in the event of abnormal CURVE PLATE DISSIPATION
circuit operation, and protection of the tube circuits in the WATTS
event of abnormal tube operation. eA
2000
Power tubes require mechanical protective devices such as C 3000
interlocks, relays, and circuit breakers. Circuit breakers D 4000
alone may not provide adequate protection in certain power- 5000
tube circuits when the power-supply filter, modulator, or
pulse-forming network stores much energy. Additional t "1It-' o f (1
protection may be achieved by the use of high-speed elec-
troniccircuits to bypass the fault current until mechanical AIR FLOW -CUBIC FEET PER MINUTE
circuit breakers are opened. These circuits may employ a
controlled gas tube, such as a thyratron or ignitron, depend- zo
ing on the amount of energy to be handled. i

The voltages applied to power tubes are extremely dangerous. 0 50 100 150 200 250 300
Great care should betaken during the adjustment of circuits.
The tube and its associated apparatus, especially all parts PLATE CORE TEMPERATURE oC (SOLID LINE)
which may be at high potential above ground, should be 7 23456
housed in a protective enclosure. The protective housing
should be designed with interlocks so that personnel can not PRESSURE DROP —INCHES H2O (DASHED LINEI
possibly come in contact with any high-potential point in 92LM-3223R7
the electrical system. The interlock devices should function
to break the primary circuit of the high-voltage supplies and Figure 4 — Typical Cooling Characteristics
discharge high-voltage capacitors when any gate or door on
the protective housing is opened, and should prevent the To Plate, Grid-No.2 and Grid-No.1 Terminals — A sufficient
closing of this primary circuit until the door is again locked. quantity of air should be allowed to flow past each of these
terminals so that its temperature does not exceed the specified
A time-delay relay should be provided in the plate-supply maximum value of 250o C.
circuit to delay application of plate voltage until the fila-
ment has reached normal operating temperature. To Cathode-Filament and Filament Terminals — A sufficient
quantity of air should be blown directly at these terminals
An interlocking relay system should be provided to prevent so that their temperature does not exceed the specified
application of plate voltage prior to the application of suf- limit of 250o C. A value of at least 40 cfm is recommended.
ficient bias voltage otherwise, with insufficient bias, the
resultant high plate current may cause excessive plate During Standby Operation —Cooling air is required when
dissipation with consequent damage to the tube. RF load only filament voltage is applied to the tube.
shorts or other causes of high output VSWR may also
cause high dissipations, excessive voltage gradients, or During Shutdown Operation —Air flow should continue for
insulator flashover. The load VSWR should be monitored a few minutes after all electrode power is removed.
and the detected signal used to actuate the interlock system
to remove the plate voltage in less than 10 milliseconds after For further information on forced-air cooling, see Section
the fault occurs. IV.0 of 10E-300 and also AN-4869, "The Application Guide
for Forced Air Cooling of RCA Power Tubes".
Forced-Air Cooling

Air Flow:
Through radiator —Adequate air flow to limit the plate-core
temperature to 250o C should be delivered by a blower
through the radiator before and during the application of
filament, plate, grid-No.2 and grid-No.1 voltage.

For a plate dissipation of 5000 watts and an incoming air
temperature of 50o C, and air flow of 105 cfm is required
in accordance with the Typical Cooling Characteristics as
shown in Figure 4.

4

8988

Tube Removal From Socket (Suggested Design►
The tube should not be removed from the socket by rocking
the tube back and forth. This motion crushes the contact
fingers and applies undue force to the internal structure
of the tube.

It is recommended that the tube be removed from the socket
with an assembly similar to that shown in Figure 5. The
extractor portion should be constructed with the dimensions
shown in Figure 6.

Figure 6 - Tube Extractor 92CS-9759RIv

Tabulated Dimensions* Notes

Dim. Inches Millimeters Material 1 /16" CRS
46 Slot between holes
A 1.8 79 Round all edges
B 3.1
C 0.06 1.5
D 0.7 18
E Dia. 0.250
F Radius 1.175 6.35
G 0.9 29.85
H Dia. 0.140 23
J 8.30
K 4.50 3.56

KEV SLOTS ~ EXTRACTOR STUDS 'Basic dimensions are in inches unless otherwise specified. Metric
dimensions are derived from the basic inch dimensions. One inch
Figure 5 - Recommended Tube Puller equals 25.4 mm.

NOTE2 Tabulated Dimensions*

AIR COOLED Dim. Inches Millimeters
RADIATOR 4.510 + .060 114.6 ± 1.5
A Dia.► 3.250 ± .015
PLATE CORE B Dia.► 82.55 ± 0.38
TEMPERATURE C Dia.► 3.028 ± .014
MEASUREMENT 2.319 ± .012 76.91 ± 0.36
POINT D Dia.► 1.850 ± .010 58.90 ± 0.30
E Dia.► 1.200 ± .010 46.99 ± 0.25
v' F Dia.► 0.617 ± .003 30.48 ± 0.25
G Dia.► 5.300 ± .080 15.67 ± 0.08
GRID No.2 U H 4.345 ± .045 134.6 ± 2.0
TERMINAL J 1.790 ± .040 110.4 ± 1.1
GRID No.l 1 M 1.330 ± .030
TERMINAL N 0.200 ± .025 45.5 ± 1.0
I P 0.475 ± .030 33.8 ± 0.8
FILAMENT-CATHODE S 0.725 ± .040
TERMINAL REFERENCE T 0.955 ref. 5.1 ± 0.6
SURFACE - U 0.250 min. 12.1 ± 0.8
MEAT SINK V 0.375 min. 18.4 ± 1.0
FILAMENT-TERMINAL W 0.220 min. 24.3 ref.
X 0.325 ref.
Y 0.160 min. 6.35 min.
1.945 ref. 9.53 min.
Z
AA 5.59 min.
8.26 ref.
4.06 min.
49.40 ref.

NOTE 3 SEAL TEMPERATURE Note 2 - Keep all stippled regions clear. Do not allow
~ MEASUREMENT POINT
contacts or circuit components to intrude
J SEE NOTE 2 into these annular volumes.

I~ CERAMIC 92LM-~SC9R7 Note 3 - Tapped 1 /4-20 NC x 0.5 inch (12.7 mm)
deep.
Note 1 -The diameter of each terminal is maintained only over
the indicated minimum length of its contact surface. 'Basic dimensions are in inches unless otherwise speci-

Figure 7 - Dimensional Outline fied. Metric dimensions are derived from the basic
inch dimensions. One inch equals 25.4 mm.

5

8988

Mounting Tabulated Dimensions"
See the preferred mounting arrangement. For other arrange-
ments, cavity-type mounting for multiple-ring terminal-type Dimension Inches Millimeters Notes
tubes, may be constructed by using either fixed or adjustable Note 1
contact rings of finger contact strips in the transverse plane C Dia. 3.220 81.79 Note 1
as described in Section IV.C.3 of 10E-300. D Dia. 2.510 Note 1
63.75
E Dia. 2.040 Note 2
F 0.215 51.82
G 0.430 5.46 Note 3
H 0.475
SEE DETAIL A J 0.015 10.92
K 0.800 12.07
M Dia. 0.600
N 0.125 0.38
P 1.000 min. 20.32
S Dia. 0.850 15.24
T Dia. 0.765
U Dia. 1.220 3.18
V 0.125 25.40 min.
W 1.000 min. 21.59
X Dia. 1.060 19.43
Y Dia. 0.975 30.99

3.18
25.40 min.
26.92
24.77

SEE DETAIL B 'Basic dimensions are in inches unless otherwise specified. Metric
dimensions are derived from the basic inch dimensions. One inch
12 SLOTS 12 SLOTS equals 25.4 mm.
J WIDE x K DEEP J WIDE x K DEEP

Fes-- M —►{ FULL 1 Note 1 —The tolerance for the indicated dimension is:
RADIUS plus 0.010 inch (0.25 mm)
FULL minus 00 inch (00 mm)
RADIUS
Note 2 —The tolerance for the indicated dimension is:
plus 00 inch (00 mm)
minus 0.002 inch (0.05 mm)

Note 3 — The tolerance for the indicated dimension is:
plus 0.002 inch (0.05 mm)
minus 00 inch (00 mm)

Note 4 — Finger stock is No.97-135-A, as made by:
Instrument Specialties Company
Little Falls, NJ 07424

Note 5 — Sockets and chimneys are available and may be obtained
in limited quantities from RCA and in production
quantities from:
Jettron Products Inc.
56 Route Ten
Hanover, NJ 07936

DETAIL A DETAIL e Supplier Socket No. Chimney No.
RCA J-15283 J-15286
92LM-4550 Jettron CD 89-085 8822

Figure 8 — Preferred Mounting Arrangement

RCA~Solid State DivisionlElectro Optics and DeviceslLancaster, PA 17604