With the trend toward unattended communications equipment, automatic switching over remote circuits has become necessary to meet the requirements of new transmitter and receiver equipment. Advancements in speed introduced by missile and newer airplane technology has forced early-warning communications systems to operate at higher switching speeds with increased reliability. Switching devices in these applications are exposed to extreme environmental conditions that can wreak havoc on conventional switch contacts. The need to devise new switching methods with far greater circuit efficiency than that exhibited by any previous switching method became obvious. In the commercial arena as well, higher power requirements and the necessity for continuous operation with the least number of costly traffic delays dictated the need to change to a long-life, maintenance-free, maximum-reliability RF switching device. Vacuum coaxial relays successfully meet the requirements of both government and commercial needs. The vacuum dielectric enables high speed switching and provides low, stable contact resistance. In addition, the vacuum environment protects the contacts from contamination and oxidation and eliminates the need for contact maintenance.

Vacuum & Gas-Filled Relays & Coaxial Relays

Vacuum Coaxial Relays Overview Jennings High-Voltage Vacuum Coaxial Relays

Vacuum Dielectric Advantages The high dielectric strength of a vacuum is one of the important features that distinguish Jennings vacuum coaxial relays from other types of coaxial relays. As a rule of thumb, a vacuum device has a dielectric strength of about 1000 volts per mil. Consequently, only a slight contact separation is required to withstand high voltages. Physically, such limited contact movement minimizes the size of the relays, permits the use of a small, simple actuating mechanism and results in faster switching times. Internal grounding minimizes crosstalk.

Application Versatility

The use of a vacuum as a contact environment also serves to increase operating reliability and the life of the relay. The absence of oxygen prevents contact corrosion and the formation of oxides and organic materials (both of which could negatively affect circuit performance due to increased circuit resistance). The RF contact resistance in the vacuum relay remains low and stable throughout the rated life of the switch.

Vacuum relays, complete with auxiliary fittings for coaxial systems and custom-designed control systems to ensure safe, reliable switching, are available to meet all power requirements of ship-to-shore, air-to-ground and ground-to-ground radio communications. System flexibility, made possible because of the operating features of these devices, is extremely broad. Customers are encouraged to discuss application specifics with Jennings engineers, who can make recommendations to assure the optimum system at minimum cost ([email protected]).

50 Ohm Transmission Systems

Examples of the various techniques practical with these relays are:

In addition to long life and high reliability, vacuum coaxial systems also offer assurance of excellent performance for HF and UHF radio systems. The elimination of oxidized contacts eliminates the noise generation and intermodulation distortion that can occur when oxides form and cause rectification of the RF signal. Because the contact resistance of vacuum coaxial relays is very low and stable, these units offer very low circuit losses. RF insertion loss is typically between 0.02 and 0.1 dB at operating frequencies. Jennings vacuum relays are distinguished by very low thermal and RF noise generation. The small relay size made possible by the use of vacuum as a dielectric medium is the smallest size possible commensurate with power handling capability and high voltage stand-off rating. Typical operating speeds of between 5 and 50 milliseconds are much faster than that available from conventional coaxial relays.

• Connector flexibility — Different connectors can be used as long as the power level rating is not affected. • Improved isolation — Even greater isolation can be obtained by connecting two switches in series. • Higher impedance operation — Although relays are designed for 50 ohm systems, they have been used at higher impedances. Contact us to discuss your application.

Reliability Long-term use in large commercial, military and space programs around the world has proven the reliability of Jennings vacuum relays. Applications range from highly complex, multiple antenna transmitter switching systems, which depend upon flawless operation of the control system and individual coaxial relays, to radio installations on military mobile vehicles or high altitude airborne systems with extreme environmental requirements. Jennings vacuum coaxial relays have a recorded history of dependable, maintenance-free operation. Because of this, they were chosen for ground and airborne applications for the tracking network of the AWACS military program.

Jennings Technology Tel: 408-282-0363 [email protected]

49

Description

COAXIAL SWITCH POWER RATINGS 1000

The construction of a typical Jennings vacuum coaxial relay for rigid lines is illustrated by the cutaway view shown on previous page. The material of the relay body is of OFHC copper with the inner conductors sealed into the ends of the housing by vacuum-tight ceramic disk insulators. The inner conductors are electrically connected by means of a switch plate slotted for multiple, positive contact.

ALL RATINGS SHOWN ARE BASED ON UNITY VSWR. USE DERATING CURVE FOR SPECIFIC APPLICATIONS. AVERAGE POWER RATING IN KW

Vacuum & Gas-Filled Relays & Coaxial Relays

Vacuum Coaxial Relays Overview

A metal bellows on the movable contact allows movement within the vacuum chamber and maintains the vacuumtight seal. The unique design of the inner conductors provides the necessary compensation to maintain the 50 ohm impedance of the line. The actuating mechanism is a bi-stable device using permanent magnets, which operate as positive latching devices and aid in the open/close function of the relay. Further drive power for contact movement in either direction is provided by a balanced spring, which also acts to neutralize atmospheric pressure. Small momentary-duty coils transfer the magnetic field of the magnets, thereby releasing their latching hold and initiating contact operation.

100

RC2

1

RC2

6, R

C27

10

1 .5

Need a Coaxial Relay You Don’t See in this Catalog? The vacuum coaxial relays featured here represent just a few of our standard models. Many other Jennings vacuum coaxial relays are available on request. Contact us today at [email protected] to discuss your application.

Fd =

VSWR - 1

100

1000

.9 .8 .7 Fd

1+

10 FREQUENCY (MHz)

COAXIAL SWITCH DERATING FOR VSWR

1.0

R1 – SWITCH RATING AT UNITY VSWR. (1.1) R2 – SWITCH RATING AT KNOWN VSWR. (N:1) Fd – DERATING FACTOR FdR1 = R2

1

2

.6 .5 .4

VSWR + 1

.3

VSWR

.2 .1

VACUUM ENCLOSURE

1:1

2:1

3:1

4:1

OUTER CONDUCTOR CERAMIC INSULATION

5:1

6:1

7:1

8:1

VSWR

CROSSTALK 90

SWITCH PLATE LONG LIFE METAL BELLOWS GROUNDING SLEEVE AUXILIARY CONTACTS

50 RC21, RC26, RC27

20

EFFICIENT MAGNETIC CIRCUIT

30

COILS

100

1000 FREQUENCY (MHz)

ARMATURE PERMANENT MAGNETS

MANUAL CONTROL

Figure 1 — Typical Jennings Vacuum Coaxial Relay for Rigid Lines

50

CROSSTALK TYPICAL (dB)

CORROSION-FREE CONTACTS

Jennings Technology Tel: 408-282-0363 [email protected]

Vacuum Coaxial Relays

SPDT

3.125"

WEIGHT, LB. (KG)

OPERATE. TIME**

POSITION INDICATORS

ACTUATING VOLTAGE

ACTUATION

INPUT/OUTPUT LINE SIZE

4.8

MS receptacle

CONTACT CONFIG.

ACTUATOR COIL CONNECTION

INSERTION LOSS

CROSSTALK

VSWR

1.15:1 Greater 0.01 than 60 dB dB 50 @Max. 500 isolation MHz @ 30 MHz Max.

COIL RESISTANCE (Ω ±10%)

90 kW CW @ MHz 0–500 RC21A5510F14B 2 30 MW Peak MHz Spec. Order

CHARACTERISTIC IMPEDANCE Ω

CAT. NO.

FREQUENCY RANGE

POWER RATING*

RC21 Series Vacuum Coaxial Relays, 90kW

DPDT Permanent Aux. 50 magnet latching, 26.5VDC 14 Auto Contacts msecs. (6.35) electrical De-energize and Visual Max. or manual Indicator

* This power rating is for the frequency at which the relay is most commonly used. ** Faster operating times can be obtained on most units by coil pulse circuits. Please contact us for details.

Vacuum & Gas-Filled Relays & Coaxial Relays

RC21 Series

RC21 Form: SPDT

CONNECTOR RECEPTACLE CONNECTOR 4.50 4.50 ACCEPTS MS 4.50 RECEPTACLE ConnectorMS CONNECTORS ACCEPTS Receptacle Accepts 20-27S CONNECTORS MS Connectors SHELL SIZE 20-27S Shell Size 20-27S SHELL SIZE 5.19 5.19 5.19

4.78 ± 8.13 (111.04.78 ± 3.30) 8.13 4.78±±8.13 (111.0 3.30)3.50 (111.0±±3.30) 3.50 3.50 .41 DIA., 6 HOLES. 60 APART. 4.375 B.C. .41 DIA., 6 HOLES. 12.88 ± .13 .41 APART. DIA., 6FOR Holes 3 FLANGES 3601/8 B.C. 60 4.375 Apart. 4.375 B.C. (327.15 ± 3.30) 12.88 .13 COAX LINE PER FOR EIA 31/8 33FLANGES 12.88 ± ±.13 Flanges for 31/8 (327.15 ± ±3.30) (327.15 3.30) STANDARD RS-225 COAX LINE Coax Line PerPER EIA EIA Standard RS-225 STANDARD RS-225 4.19 ± .06 4.19 .06 4.19 ± ±.06

4.19 ± .064.19 4.19 ±.06 ± .06 8.38 ± .06 (212.85 ± 1.52) 8.38 .06 8.38±±.06 (212.85 1.52) (212.85 ± ±1.52)

Auxiliary contacts Auxiliary contacts notindicated indicated arearenot Auxiliary contacts are not indicated

Jennings Technology Tel: 408-282-0363 [email protected]

51

RC265552G24F 90 kW CW @ 30 MHz 0–600 2 MW Peak MHz 50 RC275576G24F Spec. Order

1.1:1 Greater 15,000 Max. than 60 dB 0.01 operating 35,000 to isolation @ dB feet 400 30 MHz Max. hours min. MHz

26

2 sec. 5 amps 19 Ω max. 5 -55˚ C max. nominal 22 amps to per coil msec. resistive +85˚ C min.

WEIGHT, LB. (KG)

NORM. OPERATE PRESSURE

PRESSURIZATION

MAX. OPERATE TEMP.

45 31± 1.5 14 PSIA (6.35) +71˚ C PSIA Dry Dry Air Nitrogen 13 (5.9)

* This power rating is for the frequency at which the relay is most commonly used. ** Faster operating times can be obtained on most units by coil pulse circits. Please contact us for details.

RC27

RC26 Switch Assembly

Attenuator

Form: SPDT

Form: SPST

4–40 UNC-2B CONNECTOR THRU 2 HOLES MS 3114H-14-19P CG

4-40 4–40UNC-2B UNC-2B Thru 22Holes THRU HOLES CG CG

1.0 1.0

4–40 UNC-2B THRU 2 HOLES CG 2.07 (52.58) 1.0

RE OUT

11.50 MAX. Max. 11.50 (292.10 MAX.) Max.) (292.10

RE OUT

11.50 MAX. (292.10 MAX.) 4.12

RE OUT

4.12 Connector CONNECTOR MS MS 3114H-14-19P 3114H-14-19P

RE OUT

11.50 MAX. (292.10 4.12MAX.)

CONNECTOR MS 3114H-14-19P

RE OUT

4.12

4.12 1.0 CONNECTOR 1.32 MS 3114H-14-19PW 2.75

INTERLOCK (DUMMY LOAD) SWITCH INTERLOCK IN SWITCH INTERLOCK (ANTENNA) DUMMY LOAD INDICATOR DUMMY LOAD INDICATOR COM SWITCH MONITOR INTERLOCK (DUMMY LOAD) Interlock (Dummy Load) SWITCH MONITOR COM IN SWITCH INTERLOCK Switch Interlock In SHIELD GROUND SWITCH INTERLOCK (ANTENNA) Switch Interlock (Antenna) INTERLOCK (DUMMY LOAD) SAFETY GROUND DUMMY LOAD Dummy LoadINDICATOR Indicator SWITCH INTERLOCK IN + 28 VDUMMY (ANTENNA) LOAD COMCom Dummy LoadINDICATOR Indicator SWITCH INTERLOCK (ANTENNA) SOLENOID COM SWITCH MONITOR Switch Monitor DUMMY4.40 LOAD INDICATOR + 28 VSWITCH (DUMMY LOAD) COM MONITOR MAX. Switch Monitor Com Max. COM SHIELD GROUND DUMMY 4.40 LOAD INDICATOR Ground (111.76 MAX.) Shield SWITCH MONITORMax.) (111.76 SAFETYGround GROUND Safety 2.15 SWITCH MONITOR COM + 28 V(Antenna) (ANTENNA) + 28V SHIELD GROUND SOLENOIDCom COM Solenoid SAFETY GROUND + 28 V(Dummy (DUMMY LOAD) 4.40 MAX. + 28V Load) + 28 V (ANTENNA) 8.25 ± .03 (111.76 MAX.) 8.25 ±.03 SOLENOID COM 2.15 (209.55 ± .76) (209.55 ±76) 4.40 MAX. + 28 V (DUMMY LOAD)

MAX.) 2.07 2.15 (111.76 INTERLOCK (DUMMY LOAD) Interlock (Dummy Load) 8.25 ± Switch .03 (52.58) SWITCH INTERLOCK Interlock 4.12 4.12 ATTENUATOR INTERLOCK (ANTENNA) Attenuator Interlock (Antenna) (209.55 ± .76) 2.07 TEST PULSE Test PulseDISABLE Disable 3.19 8.25 ± .03 (52.58) TEST PULSE DISABLE COMCom Test Pulse Disable 3.20 Attenuator Monitor ATTENUATOR MONITOR CG (209.55 ± .76) 4.55 Attenuator Monitor Com ATTENUATOR MONITOR COM 1.32 RF 4–40 UNC-2B Shield Ground SHIELD GROUND INTERLOCK (DUMMY LOAD) 2.75 OUT CONNECTOR Safety Ground SAFETY GROUND THRU 2 HOLES 3.19 SWITCH INTERLOCK ++ 28 28V (Antenna) DUMMY LOAD V (ANTENNA) 1.32 1.32 Connector MS 3114H-14-19PW ATTENUATOR 3.20INTERLOCK (ANTENNA) CONNECTOR SOLENOID COM Solenoid Com (RF OUT) 4.55 TEST PULSE DISABLE MS 3114H-14-19W 2.75 + 28 V (DUMMY LOAD)Load) 3.19 3.19 28V (Dummy TEST PULSE DISABLE COM MS 3114H-14-19PW + 1.32 1.32 3.20 ATTENUATOR MONITOR CG 3.20 4.55 ATTENUATOR MONITOR COM 4–40 UNC-2B CG SHIELD GROUND 1.0 SAFETY GROUND THRU 2 HOLES 4–40 UNC-2B UNC-2B 4-40 2.75 1.86 + 28 V (ANTENNA) 1.90 5.81 ± .06 THRU HOLES Thru 22Holes 4.55 .22 .66 SOLENOID COM ± .03 LOAD) +8.37 28 V (DUMMY (115.57) 1.32 1.32 (212.60 ± .76) 1.32 1.32 1.0 1.0 2.75 1.86 5.81 .06 5.81 ±±.06 RF RF 4.55 .22 2.75 2.75 1.90 1.86 8.37 ±.03 1.90 8.37 ± .03 In IN5.81 ± .06 (115.57) .66 4.55 .22 .66 (212.60 ±76) COAX SWITCH (212.60 ± .76) Coax Switch 8.37 ± .03 (115.57) (212.60 ± .76)

RF

52

AMBIENT TEMP. RANGE

AUX. SWITCH RATING

COIL CURRENT DURATION

COIL RESISTANCE

COIL CURRENT

COIL VOLTAGE (V ±10%)

MAX. OPERATING ALTITUDE

SERVICE LIFE

INSERTION LOSS

CROSSTALK

VSWR

CHARACTERISTIC IMPEDANCE Ω

CAT. NO.

FREQUENCY RANGE

RC26 and RC27 Series Vacuum Coaxial Relays, 90kW

POWER RATING*

Vacuum & Gas-Filled Relays & Coaxial Relays

RC26 and RC27 Series

RE OUT

0

Vacuum Coaxial Relays

RF RF OUT OUT DUMMY LOAD ATTENUATOR (RF OUT) (RF OUT) RF RF RF RF IN Out Out OUT OUT DUMMY ATTENUATOR Dummy LOAD Load Attenuator RF (RF (RF (RFOUT) Out) OUT (RFOUT) Out) RF IN In RF ATTENUATOR INTERLOCK (DUMMY LOAD) (RF OUT)SWITCH INTERLOCK ATTENUATOR INTERLOCK (ANTENNA) RF IN

1.32

TEST PULSE DISABLE TEST PULSE DISABLE COM ATTENUATOR MONITOR ATTENUATOR MONITOR COM SHIELD GROUND SAFETY GROUND + 28 V (ANTENNA) SOLENOID COM + 28 V (DUMMY LOAD)

1.0 RF Out OUT ANTENNA Antenna

RF

Jennings Technology IN OUT Tel: COAX408-282-0363 SWITCH ANTENNA [email protected]

RF IN COAX SWITCH

RF OUT ANTENNA

In this section...

Vacuum Capacitors

Vacuum Capacitors Vacuum Capacitors Overview..................................................54–65 Fixed Capacitors.....................................................................66–74 Capacitor Accessories...................................................................75 Variable Capacitors.................................................................76–98

Vacuum Capacitors 54

Vacuum Capacitors Overview Capacitor Selection Guides Capacitors by Type CAPACITOR TYPE Vacuum Variable

CAPACITY MAX. (PF)

TEST VOLTAGE 60/50 HZ

MODEL NO. SERIES

PAGE NUMBER

25 30 30 30 60 100 100 125 150 250 250 250 250 300 300 400 450 450 500 500 500 500 500 500 500 500 650 650 650 650 650 750 750 900 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000 1300 1400 1500 1500

45, 50, 55 7.5, 10, 15 7.5, 10, 17.5 7.5, 10, 15 10, 15 7.5, 10, 15 7.5, 10, 15 3.0, 5.0 7.5, 10, 15 3.0, 5.0 3.0, 5.0 30, 35, 40 45, 50, 55 7.5, 10, 15 3.0, 5.0 7.5, 10, 15 30, 35, 40 45, 50, 55 3.0, 5.0 3.0, 5.0 7.5, 10, 15 10, 15, 20 7.5, 10, 15 5.0, 8.0 5.0, 7.0 15 45, 50, 55 5 8 45, 50, 55 40, 45, 50 7.5, 10, 15 30, 35, 40 3.0, 5.0, 6.0 30, 35, 40 3 3.0, 5.0 7.5, 10, 15 30, 35, 40 40, 45, 50 40, 45, 50 3.0, 5.0 3.0, 5.0 5 40, 45, 50 3 3.0, 5.0 7.5, 10, 15

CVHD-25 CADC-30 CADD-30 CVDD-30 CVDD-60 CVDD-100 C/GCS-100 CACAN-125 CVDDN-150 CACAN-250 CVCD-250 CVFP-250 CVHP-250 CVDD-300 CSV1-300 CVDD-400 CVFP-450 CVHP-450 CSV1-500 CSVS-500 CVDD-500 CVEP-500 M/CSVF-500 M/CSV5-500 M/CSV6-500 PV4-500 CAV3-650 CMV1-650 CMV3-650 CVHP-650 CWV3-650 CVDD-750 CVFP-750 CSV4-900 CAV2-1000 CMV1-1000 CSV1-1000 CVDD-1000 CVFP-1000 CVHP-1000 CWV5-1000 M/CVCJ-1000 M/CSV5-1000 PV4-1000 CWV5-1300 CSV4-1400 CVCD-1500 CVDP-1500

76 76 76 77 77 78 78 78 79 79 79 80 80 81 81 81 82 82 83 83 83 84 84 84 85 85 86 86 86 87 87 88 88 88 89 89 89 90 90 90 91 91 91 92 92 92 93 93

Jennings Technology Tel: 408-282-0363 [email protected]

CAPACITOR TYPE Vacuum Variable

Vacuum Fixed

Gas Variable Gas Fixed

CAPACITY MAX. (PF)

TEST VOLTAGE 60/50 HZ

MODEL NO. SERIES

PAGE NUMBER

1500 1600 1600 1600 1600 2000 2000 2000 2050 2300 3000 4000 25 50 100 150 200 250 25 50 100 50 80 100 150 180 210 100 175 350 500 1000 300 450 500 750 750 1000 1000 1500 1500 2000 2000 45 260

30, 35, 40 55, 60, 65 30, 35, 40 35, 40 50, 55, 60 3.0, 5.0 10, 15 25, 30, 35 40, 45, 50 7.5, 10, 15 3.0, 5.0 5 35 35 35 30 30 30 25 25 25 15 15 15 15 15 10 35 35 15 12 10 45, 50, 55, 60 45, 50, 55 10, 15, 20, 25 40, 45, 50 10, 15, 20, 25 40, 45, 50 10, 15, 20, 25 7.5, 10, 15 25, 30, 35 7.5, 10, 15 25, 30, 35 3.0, 5.0, 7.5 40, 45, 50

CVFP-1500 CWV1-1600 CWV2-1600 CWV3-1600 CWV4-1600 CVCD-2000 CVEP-2000 CVFP-2000 CWV4-2050 CVDP-2300 CVCD-3000 CMV1-4000 CKT-25 CKT-50 CKT-100 CKT-150 CKT-200 CKT-250 CKT1-25 CKT1-50 CKT1-100 CF2-50 CF2-80 CF2-100 CF2-150 CF2-180 CF2-210 CFC-100 CFC-175 CFC-350 CFC-500 CFC-1000 CFHD-300 CFHP-450 CFED-500 CFHP-750 CFED-750 CFHP-1000 CFED-1000 CFDP-1500 CFFP-1500 CFDP-2000 CFFP-2000 CHV1N-45 CGF1-260

93 94 94 95 95 96 96 96 97 97 98 98 66 66 66 66 66 66 67 67 67 68 68 68 68 68 68 69 69 69 69 69 70 70 70 71 71 71 72 72 72 73 73 74 74

Capacitors Alpha Listing by Model Number ALPHA LISTING BY MODEL NO.

ALPHA LISTING BY MODEL NO. MODEL NO. SERIES CACAN-125 CACAN-250 CADC-30 CADD-30 CAV2-1000 CAV3-650 CF2-100 CF2-150 CF2-180 CF2-210 CF2-50 CF2-80 CFC-100 CFC-1000 CFC-175 CFC-350 CFC-500 CFDP-1500 CFDP-2000 CFED-1000 CFED-500 CFED-750 CFFP-1500 CFFP-2000 CFHD-300 CFHP-1000 CFHP-450 CFHP-750 C/GCS-100 CGF1-260 CHV1N-45

PAGE NUMBER 78 79 76 76 89 86 68 68 68 68 68 68 69 69 69 69 69 72 73 72 70 71 72 73 70 71 70 71 78 74 74

MODEL NO. SERIES

PAGE NUMBER

CKT-100 CKT-150 CKT-200 CKT-25 CKT-250 CKT-50 CKT1-100 CKT1-25 CKT1-50 CMV1-1000 CMV1-4000 CMV1-650 CMV3-650 CSV1-1000 CSV1-300 CSV1-500 CSV4-1400 CSV4-900 CSVS-500 CVCD-1500 CVCD-2000 CVCD-250 CVCD-3000 CVDD-100 CVDD-1000 CVDD-30 CVDD-300 CVDD-400 CVDD-500 CVDD-60 CVDD-750 CVDDN-150

66 66 66 66 66 66 67 67 67 89 98 86 86 89 81 83 92 88 83 93 96 79 98 78 90 77 81 81 83 77 88 79

ALPHA LISTING BY MODEL NO. MODEL NO. SERIES

PAGE NUMBER

CVDP-1500 CVDP-2300 CVEP-2000 CVEP-500 CVFP-1000 CVFP-1500 CVFP-2000 CVFP-250 CVFP-450 CVFP-750 CVHD-25 CVHP-1000 CVHP-250 CVHP-450 CVHP-650 CWV1-1600 CWV2-1600 CWV3-1600 CWV3-650 CWV4-1600 CWV4-2050 CWV5-1000

93 97 96 84 90 93 96 80 82 88 76 90 80 82 87 94 94 95 87 95 97 91

CWV5-1300

92

M/CSV5-1000

91

M/CSV5-500

84

M/CSV6-500

85

M/CSVF-500

84

M/CVCJ-1000

91

PV4-1000 PV4-500

92 85

Vacuum Capacitors

Vacuum Capacitors Overview Capacitor Selection Guides

See page 57 for details.

See page 60 for details.

Jennings Technology Tel: 408-282-0363 [email protected]

55

Vacuum Capacitors

Vacuum Capacitors Overview Jennings Vacuum Capacitors Features • High Voltage Rating — The dielectric strength of the vacuum permits optimized voltage rating for a given size and capacity, in addition to freedom from contamination, humidity and oxidation. • High Current Rating — Low losses and rugged copper construction permit the handling of high RF currents with convection cooling only. Some of our designs offer water and air cooling for extraordinary load conditions. • Wide Tuning Ranges — High ratio of maximum to minimum capacity (up to 175:1) make Jennings vacuum capacitors desirable for wide tuning ranges. • Low Losses — Losses in a vacuum capacitor are so small that for most applications they can be considered as negligible. Construction materials and the vacuum dielectric permit the handling of large RF currents at high RF frequencies that would destroy capacitors with other dielectrics. • Self-Healing — Jennings vacuum capacitors can withstand momentary overloads that would permanently damage other dielectric materials. • High Altitude Operation — Vacuum sealing permits the operation of Jennings vacuum capacitors at high altitudes without the degradation that occurs with other types.

Description and General Specification Figure 1 illustrates the construction of a typical Jennings variable vacuum capacitor. Two sets of concentric cylinder plates, one adjustable and the other fixed, are enclosed in an evacuated ceramic envelope with OFHC copper seals at both ends. A flexible metal bellows, attached to a sleevetype bearing, maintains vacuum while allowing capacitance to vary. The linear sliding motion required to vary capacitance is converted to rotary tuning via an adjustment screw; in many capacitors, direct pull tuning is an alternative. Internal breakdown voltage is primarily determined by the spacing of the opposing plates and a high vacuum level. The following are general specifications pertaining to Jennings vacuum capacitors. Current ratings are for normal convection cooling in ambient temperature of 25° C unless otherwise specified.

VARIABLE END

CAPACITANCE ADJUSTMENT SCREW TURNING HEAD

HEAVY COPPER MOUNTING SURFACE

LONG LIFE BELLOWS ALLOWS PLATE MOVEMENT IN VACUUM

SLEEVE TYPE BEARING

SHAFT PROVIDES PLATE MOVEMENT CERAMIC ENVELOPE

PATENTED CONCENTRIC CYLINDER RE-ENTRANT FLANGE CONSTRUCTION

.................................... Specifications.................................... • Maximum Allowable Operating Temperature — 125° C (257° F) for ceramic capacitor • Cooling — Natural convection unless otherwise specified • Temperature Coefficient — Exceeds requirements of MIL-C-23183 • Mounting Position — Any • Rotation to Increase Capacity — Counterclockwise • Shock — Exceeds requirements of MIL-C-23183 • Vibration — Exceeds requirements of MIL-C-23183

If none of our standard catalog models meet your needs, our engineers will work with you to design a custom solution to meet your specific needs. Contact us today at [email protected] to discuss your application.

56

Jennings Technology Tel: 408-282-0363 [email protected]

FIXED END Figure 1 — Typical Jennings Variable Vacuum Capacitor

HEAVY COPPER PLATES

HIGH STRENGTH VACUUM DIELECTRIC

Vacuum Capacitors Overview High-current applications

Maximum operating current for vacuum capacitors is limited by temperature rise and working voltage. At lower frequencies, a capacitor is a current-limiting device as a result of its capacitive reactance. At some frequencies, the internal generation of heat exceeds the device’s heat-sinking capabilities, and its current-carrying capacity is limited by thermal considerations. A current vs. frequency chart is provided for each capacitor listed.

Jennings PV Series capacitors set a new standard for vacuum variable capacitors.

Vacuum Capacitors

Current/Voltage

Peak voltage is limited by mechanical design of the capacitor. It does not vary with frequency.

Temperature Jennings Technology vacuum capacitors are designed to meet MIL-C-23183 specifications. Our capacitors are rated for a maximum operating temperature of 125° C (257° F) with normal convection cooling at an ambient temperature of 25° C (72° F).

Current The current rating provided in the tables in this catalog is the maximum current the vacuum capacitor at maximum working voltage can handle continuously under normal convection cooling at an ambient temperature of 25° C.

Pulse Ratings Continuous RF current ratings may be exceeded for short periods if the working voltage rating is not exceeded. This applies particularly to pulse and peaks-ofmodulation applications. Momentary currents may exceed the catalog continuous current rating by a factor of the square root of the duty cycle, provided the working voltage is not exceeded.

Jennings Technology’s PV Series vacuum variable capacitors withstand rugged, highcurrent environments to meet the increasing demands of semiconductor-processing applications. Jennings quality engineers put the PV Series capacitors through rigorous testing. All tested units achieved more than 2.5 million cycles while still meeting their original specifications, and many exceeded 3.8 million cycles. For detailed test results, contact us today at [email protected]. Jennings offers PV Series vacuum variable capacitors in 500 and 1000pF capacitance. Look for them on pages 85 and 92 of this catalog.

Amplitude Modulation Ratings Capacitors in AM service must be able to withstand peaks-of-modulation voltage and current. Current ratings are based on temperature, so the heating effects of the modulated currents determine the capacitor requirements. The average output power of an AM transmitter that is 100% sine wave modulated is 1.5 times the unmodulated carrier power. The average modulated carrier current is 1.225 times the unmodulated carrier current. Therefore, a capacitor current rating of 1.2 times the carrier current will be sufficient, even though the peaks-ofmodulation currents are twice the carrier current.

Jennings Technology Tel: 408-282-0363 [email protected]

57

Vacuum Capacitors

Vacuum Capacitors Overview Current (continued) Forced Air Cooled and Water Cooled If higher current ratings are required, capacitors are available with forced-air cooled bellows to operate safely at 200% of the convection-cooled rating. They are identified with a “CAV” model number. Water-cooled capacitors, identified with a model number beginning with “CW,” are also available and are normally limited only by voltage. On standard convection-cooled capacitors, current rating may be exceeded for short periods of time, providing the rated temperature rise is not exceeded. Under no conditions should the current exceed 150% of convection current rating. Fixed capacitors can carry more current because they have shorter RF impedance paths. Fixed capacitor current ratings may be increased by forced-air cooling up to voltage and temperature limitations.

Voltage Two voltage ratings are provided in our product specifications: AC Test Voltage and Working Voltage.

AC Test Voltage Is the maximum 60 Hz voltage that can be applied to the capacitor without breakdown occurring, as indicated by either internal or external arc-over. Capacitors are tested at this voltage as a means of determining the general condition of the capacitor. Customers frequently use such a test in incoming inspection to check for damage in transit. External arc-over is usually an indication of external contamination or high humidity, not a deficient capacitor.

RF Working Voltage Is the maximum peak RF voltage that can be applied continuously to the capacitor without affecting its ability to withstand instantaneous overloads. It has been established as 60% of the Peak Test Voltage rating. The difference between the 60 Hz Test Voltage and the Working Voltage values is the recommended operating safety factor. For variable capacitors, the voltage rating is essentially constant from maximum capacity to a point near minimum capacity, where it increases significantly. Within the normal accuracy of instrumentation (±3%), voltage ratings should not be exceeded. Jennings RF testing facilities monitor the above characteristics on a 100% basis, and can also do special application testing when required.

DC Vacuum capacitors should not be operated at DC voltage above the peak RF working voltage.

DC plus RF For DC plus RF applications, the sum of the DC plus the peak RF voltage should not exceed the peak RF working voltage. Capacitors for DC plus RF applications are tested for DC emission on a dielectric strength tester. To meet Jennings Quality Assurance standards, the DC emission current must not exceed ten microamps at the rated working voltage.

Amplitude Modulation The peak output power of an AM transmitter that is 100% sine wave modulated is 4.0 times the unmodulated carrier power. The peak RF voltage will be twice that of the unmodulated carrier, and the capacitor should have an RF working voltage rating equal to or greater than this voltage.

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Vacuum Capacitors Overview Vacuum Capacitors

Capacitance Fixed capacitors with a nominal capacitance above 50pF shall be within ±5%. Capacitors with a nominal capacitance of 50pF or less shall be within ±10%, or .5pF, whichever is greater. For variable capacitors, the low end will be equal to or less than minimum rating. The capacitance change is substantially uniform with rotation, and there are no capacitance reversals. Capacitance is within ±10% of the nominal value of the curves shown (Capacity vs. Turns), in the linear portion of this curve.

Automatic Shorting Feature Some variable capacitors have been designed with an internal shorting device that shorts out the capacitor when it has been turned beyond maximum rated capacitance. This feature is useful for tuning antenna couplers without the vacuum capacitor in the circuit and also serves as a reference point for adjusting the capacitor to a previously measured capacitance value.

Adjustable Capacitors Jennings Technology capacitors with a model number beginning with a “CAC” or “CAD” designation are adjustable capacitors, designed to be operated as a fixed capacitor, but able to be hand adjusted to any value within their range and then locked in position with a locking nut.

Tracking

NASA does not endorse any commercial product or service.

Pairs of variable capacitors will track within 10% if set together near the low capacity end of the linear portion of the curve. On special order, units may be obtained to closer tracking tolerances.

Torque/Direct Pull In variable capacitors, the linear sliding motion of the moving electrode assembly is converted to rotary tuning via a threaded shaft. The torque values given in the tables are the maximum torque needed to reach minimum capacitance when rotated with a standard lead screw; the torque required to tune away from minimum may be less than half this value. For most variable capacitors, direct pull tuning is an available option to rotary tuning. Maximum required direct pull force values are also given in the tables. Capacitance range end-stops are built into every variable capacitor. It is recommended that the user install their own external stops to prevent damage from gear-reduction drives.

Quality Factor (Q) Extremely low losses occur in vacuum capacitors because of the vacuum dielectric, compact construction and use of low-loss ceramic envelopes, as well as copper and precious-metal solder construction. Consequently, vacuum capacitors are able to handle large RF currents at high RF frequencies that would destroy other types of capacitors. The Q factor, or ratio of stored energy to dissipated energy, is typically in the order of 1000 to 5000 and higher.

Equivalent Series Resistance (ESR) Because Q is a function of frequency, capacity and ESR (Equivalent Series Resistance), it is perhaps more meaningful to consider the value of ESR. In modern high power capacitor applications, ESR is significant for determining cooling requirements. The slight loss results from the RF resistance in the copper. Based on actual tests, the ESR value is not affected by change in capacity, other parameters being fixed. The value of ESR varies over a range of 2 to 20 milliohms from 2 to 30 MHz.

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Vacuum Capacitors

Vacuum Capacitors Overview Thermal Stability Jennings vacuum capacitors are designed to meet MIL-C-23183 specifications, which state that the absolute value of the capacitance change with temperature shall not exceed 1.1% over the applicable operating temperature range. In typical tests, values for ceramic capacitors show a stability within 50 ppm/°C.

Salt Spray and Humidity Jennings capacitors are designed to withstand the harmful effects of salt spray and humidity without degradation in performance.

Inductance The self-inductance of vacuum variable capacitors is typically in the order of 6 to 20 nanohenries, while that of a fixed capacitor is significantly lower, in the range of 2 to 6 nanohenries. For most applications, the self-inductance can be ignored. It becomes a factor only when the ratio of capacitive reactance to inductive reactance is small.

Mechanical Life The mechanical life of variable capacitors is related to length of stroke, speed of operation, bellows material and total number of cycles. Extensive mechanical life tests have been run, operating units for complete cycles from maximum to minimum and back to maximum capacity covering 95% of the full stroke of the movable plates. Capacitors with a large bellows and a short stroke will have the greatest life expectancy under cycling operation. Our most recent variable capacitor models are rated for > 3 million cycles, ideal for the semiconductor processing industry. Jennings application engineers will be happy to review your specific application to ensure that the optimum capacitor is selected to meet your requirements. If none of our standard catalog models meet your needs, our engineers will work with you to design a custom solution to meet your specific needs. Contact us today at [email protected] to discuss your application.

Inductance in Nanohenries 15

20

800 600

Self Inductance

nc

na

eso

300

lf R

400

Se e

Capacity in Picofarads

10

200

100

30

50

80

125

Frequency in Megahertz Figure 2 — Self-Resonance and Self-Inductance vs. Capacity (Typical Data)

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Extended lifetime: Jennings Jenn-X vacuum capacitors

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Jennings Jenn-X vacuum variable capacitors offer a proven field-service life of approximately 5 million cycles — making them ideal for use in RF tuning circuits for semiconductor processing and other demanding applications, such as induction and dielectric heating, medical imaging and communications. The Jenn-X line offers significant savings in terms of both the labor and materials involved in capacitor replacement. You can use Jennings Jenn-X capacitors with confidence, knowing Jennings backs their quality and workmanship with an industry-first limited lifetime warranty that ensures prompt repair or replacement of any defective unit within the unit’s lifetime. Indicated by a model number that begins with “M/,” Jennings Jenn-X vacuum variable capacitors are available in 500pF and 1000pF maximum capacitance. Look for them on pages 84–85 and 91 of this catalog.

Vacuum Capacitors Overview When two or more capacitors are connected in parallel, the inductance of the connecting conductors acting with the capacitors form a tuned circuit.

Vacuum Capacitors

Capacitors in Parallel POOR

In high current circuits, it is possible to parallel two or more vacuum capacitors to increase capacity. Care must be taken, due to the low loss of the vacuum capacitors and the heavy copper straps paralleling the capacitors, to ensure that the frequency of this series high-Q resonant circuit is above the operating frequency. If the frequency of the series resonant circuit is allowed to become equal to the operating frequency, high currents will be generated, resulting in damage to the capacitor.

CAPACITOR

All vacuum capacitors have inductance within the connections (Figure 3). The resulting tuned circuit of two 1000pF capacitors in parallel can be kept well above 30 MHz. At low capacities of 50 to 100pF, the resonant frequency can be kept well above 100 MHz.

FLAT STRAP

BETTER

CAPACITOR

Figure 4 is a graph of resonant frequency vs. capacity of two 1000pF capacitors with low inductance connections. The resonant frequency of the resulting parellel tuned circuit varies from 20 MHz to 135 MHz from a maximum to minimum capacity.

Testing Standards LOW INDUCTANCE CONNECTOR PAN OR DISH TYPE

Factory All capacitors are tested for dielectric strength on a 100% basis prior to shipment. Upon customer request, certified test reports will be made available.

BUCKING

Figure 3 — Vacuum Capacitors with Inductance within the Connections for Better Performance

Dielectric strength is tested using a low current, high potential source at 60 Hz voltage. Capacitors for applications involving applied DC voltage should be tested on a DC dielectric strength meter for voltage and emission current. Jennings will test capacitors to this measure if specified by the customer.

User Most users will find the 60 Hz dielectric strength test adequate and relatively inexpensive. Jennings does not recommend DC testing being performed by the user because of safety considerations. If DC testing is performed, care should be taken not to exceed 60% of the peak test voltage rating of the capacitor.

Frequency (MHz)

200

RESONANT FREQUENCY TWO 1000pF CAPACITOR WITH LOW INDUCTANCE CONNECTORS (With standard strap connectors the frequency is approximatly 10% lower)

100

50

30

20

50

100

500

1000

2000

Capacitance (pF) Figure 4 — Resonant Frequency vs. Capacity

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Vacuum Capacitors

Vacuum Capacitors Overview Testing Procedure Apply 60 Hz current-limited voltage across the capacitor. One side may be grounded if desired. Increase voltage gradually. The rate of increase should be from zero to maximum voltage in one minute. Normal test procedure requires that the capacitor be able to withstand the full rated voltage without barnacles (arcing) occurring after the first minute at the test voltage. A barnacle is a self-healing, non-sustained, momentary breakdown. Weak barnacles that instantly heal are disregarded during the first minute. Under no condition should the test voltage be exceeded.

Arc Detectors In extremely critical circuit applications, some form of arc detection is necessary. An oscilloscope may be connected across the capacitor to show weak electron discharges, waveform distortion, evidence of strong DC emission currents or corona. Another form of arc detection may be improvised by using a small neon lamp with one terminal connected to the hot side of the capacitor under test and the other terminal of the lamp floating. The lamp will flash when the capacitor arcs. A contact microphone and audio amplifier connected to the base of the standoff insulator supporting the capacitor under test also makes a very sensitive arc detector.

Installation Testing Jennings vacuum capacitors are well packaged and shipped in a manner to ensure safe delivery. However, during shipping they may be subjected to extreme shock, which could damage the capacitor elements without damaging the shipping container. Therefore, capacitors should be tested upon receipt and before installation. (See Capacitor Testing Procedure above.)

HiPot Testing of Vacuum Capacitors The most important test for vacuum capacitors is the high voltage AC HiPot test. It is the indicator of the standoff capability of a capacitor. If the vacuum level of a capacitor decays or there is misalignment of the plates, the standoff capability of the capacitor will be reduced. This test is performed by applying a 50 or 60 Hz AC voltage up to the specified Test Voltage (ETest) of the capacitor. The lower the frequency of a HiPot test, the more stringent it is. Therefore, 50 or 60 Hz is used, even for capacitors to be used in RF applications. Capacitors to be used in DC applications should not be subjected to a DC voltage above the specified Operating Voltage, which is ≤ 60% of the Test Voltage. This product should only be installed by qualified personnel trained in good safety practices involving high-voltage electrical equipment.

Equipment Use a HiPot tester that is certified to meet appropriate government safety standards or an approved variable AC power supply capable of supplying the voltage required with a current-limiting resistor (R ≥ ETest/Imax) in series between the power supply and the capacitor.

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Vacuum Capacitors Overview Procedure: 1. Apply ~ 1kV @ 50 or 60 Hz to the electrodes. Increase the voltage at a rate of 20kV per minute up to ETest unless there is internal arcing (barnacling) or current flow greater than the charging current of the capacitor that persists for > 2 seconds. In that case, reduce the voltage until barnacling terminates, observe voltage and repeat the process. Continue this process as long as the voltage where arcing is encountered continues to increase up to ETest.

Vacuum Capacitors

Installation (continued)

2. If there is any external arcing at any voltage, clean the external surfaces. If conditions are extremely humid, delay testing until it can be done in a lower humidity. 3. Upon experiencing any barnacling or current flow greater than the charging current of the capacitor that persists for > 2 seconds, reduce voltage until barnacling terminates, observe voltage and repeat the process. Continue this process as long as the voltage where arcing is encountered continues to increase up to ETest and is held there for one minute without barnacling or exhibiting current flow greater than the charging current of the capacitor. 4. If there is no persistent barnacling or current flow greater than the charging current of the capacitor (up to ETest), the capacitor has passed the HiPot test. If barnacling is encountered, it is not necessarily a bad capacitor, but it may require reconditioning.

Warning During installation, avoid twisting or bending strains that could cause failure of the ceramic-to-metal seal.

Mounting Position Units may be mounted in any position. When large capacitors are mounted horizontally, both ends should be supported by standoff insulators to eliminate excessive stresses and possible damage. (Vertical mounting preferred.)

Cooling Current ratings are determined on the basis of convection cooling only. It is good design practice to provide an added safety factor by having the variable end mounted on the chassis for heat sinking and by using flexible copper straps for the fixed electrode end. When a large capacitor is being operated near its maximum current rating at high frequencies, there must be adequate space around the unit for convection cooling.

Water Cooling Consult factory for specific recommendations.

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Vacuum Capacitors

Vacuum Capacitors Overview Vacuum Capacitor Reconditioning A vacuum capacitor that has exhibited barnacling during incoming inspection, when it has been in storage, or has been used for light duty (low voltage) for a prolonged period may exhibit internal arcing (barnacling) when high voltage is first applied. If this occurs ≤ ETest, it may be an indication that the capacitor needs reconditioning or that it no longer has adequate voltage standoff capability. In this situation, we recommend the following course of action. Personnel: Jennings recommends installation only by individuals who have been trained and qualified to work safely with high voltages. Equipment: Use a HiPot tester that is certified to meet appropriate government safety standards or an approved AC variable power supply capable of supplying the voltage required with a current-limiting resistor (R ≥ ETest/Imax) in series between the power supply and the capacitor.

Procedure: 1. Apply ~ 1kV @ 50 or 60 Hz to the electrodes. Gradually increase the voltage up to ETest unless there is internal arcing (barnacling) or current flow greater than the charging current of the capacitor that persists for > 2 seconds. In that case, reduce the voltage until barnacling terminates, observe voltage and repeat the process. Continue this process as long as the voltage where arcing is encountered continues to increase up to ETest. 2. If there is any external arcing at any voltage, clean the external surfaces. If conditions are extremely humid, delay testing until it can be done in a lower humidity. 3. Upon experiencing any barnacling or current flow greater than the charging current of the capacitor that persists for > 2 seconds, reduce voltage until barnacling terminates, observe voltage and repeat the process. Continue this process as long as the voltage where arcing is encountered continues to increase up to ETest. The capacitor should be held at ETest for one minute without current flow or barnacling. Leave ETest applied for 15 to 20 minutes to complete this session of conditioning. 4. If barnacling is encountered at the same voltage or lower for three successive attempts, discontinue reconditioning. If the capacitor is in warranty, contact us at [email protected] and request an RMA number. Then return it to the factory for evaluation. If it is out of warranty, dispose of it in a safe manner. In addition, Jennings now offers repair for out-of-warranty product. Contact us with questions about this service at [email protected]. 5. If conditioning as described in paragraphs 3 and 4 was required, but it passes the one-minute test without current flow or barnacling, allow it to rest for at least 24 hours and repeat the conditioning process for up to three sessions. If it passes the one-minute test described in paragraph 3 after a 24-hour hold, it is adequately conditioned and may be placed into service. If after three sessions, the capacitor continues to barnacle, the capacitor should be replaced. This product should only be installed by qualified personnel trained in good safety practices involving high-voltage electrical equipment.

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Vacuum Capacitors Overview Vacuum Capacitors

Vacuum Capacitor Reconditioning (continued) Thermal Expansion To allow for thermal expansion, at least one end of the vacuum capacitor should have a flexible connection. In variable capacitors, the flexible connection is normally made to the fixed electrode end. Avoid heavy rigid straps or connections that produce a mechanical strain. The connections should be of substantial area to keep losses low and provide cooling by conduction from both ends. Only a small degree of flexibility is required.

Electrical Connections Both ends of the capacitor may be “hot,” or one end may be grounded. Because of the high voltages present, there must be sufficient clearance between the vacuum capacitor and other components to prevent high voltage breakdown. Although the capacitors are designed to ensure optimum electrical field distribution, mounting should be such that adjacent components do not upset this normal electrical field and thus result in excessive heating.

Magnetic Influences Strong magnetic influences can induce heating and affect performance of capacitors. Electromagnets have greater effect than permanent magnets.

Transients and Parasitics Where the possibility exists of external arcs from transients or parasitic voltages, the capacitor should be protected by adequate corona, or arc shields. Ball gaps are recommended when protection from simple voltage arc cover is required.

Lead Lengths At high frequencies, avoid long lead length, because the reactance of the strap will subtract from the reactance of the capacitor and effectively increase the total capacitance. In some cases, the total reactance may be reduced to the point where the minimum capacity of the capacitor will appear too high.

Side Loading Side loading (radical force applied to lead screw) will greatly accelerate wear and significantly reduce life. A flexible coupler connection to the lead screw is highly recommended. Increased frequency of 100% minimum to maximum cycling will also be helpful. (See Maintenance.)

Other Precautions Capacitors should not be used as standoff insulators to support heavy assemblies. Only the part of the capacitor specified as the mounting area should be used for that purpose, and any clamps or straps must be attached carefully to avoid stress on the unit, possibly causing seal failure.

WARNING DISCONNECT POWER BEFORE SERVICING. HAZARDOUS VOLTAGE CAN SHOCK, BURN OR CAUSE DEATH.

Solder connections should not be made directly to the body of the capacitor, nor should there be any contact with the ceramic insulator during operation.

Maintenance Capacitors operated at normal temperature in a clean environment require no maintenance except to keep them free of dirt accumulation and moisture that may cause a drop in external insulation resistance. A special glaze is applied to all Jennings ceramic capacitors to avoid absorption of moisture and foreign matter. For variable capacitor applications involving frequent adjustment over a limited range, such as semiconductor impedance matching, it is advisable to cycle completely between minimum and maximum at least 2 cycles every 10,000 cycles to redistribute lubricant. If variable capacitors are being operated at high temperatures, it is advisable to periodically lubricate the shaft and bearing with a good grade of high temperature light oil and the lead screw with a high temperature, extreme pressure grease.

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