High-energy-physics - AM89/C-Band-400W-CW/Pulsed
The series AM89 covers frequencies of 5.68GHz to 5.72GHz and has a maximum output power of 400 watts
Utilising the latest GaN power transistor technology, the AM89 series amplifier is designed for high efficiency. With fast rise times & low pulse distortion the amplifier is ideally suited to applications in high-energy physics, typically as drivers for Klystron tubes. A control line is provided for remote operation, whilst RF samples of forward and reflected power are available for monitoring. Protection circuits are incorporated to ensure safety and long-term reliability.
Available as stand-alone 19" rack mountable instrument with a duty based cooling system. AC-DC power supply available separately. Water cooled options are available for CW models.
The amplifier may be operated in class A, or in a Gated mode, with the RF transistor bias controlled by a TTL command synchronised with the RF pulse. The transistors are in a biassed state only during the RF pulse, and otherwise in standby. This design provides the superior performance possible from a class AB design but without the disadvantages of high power consumption and heat generation, whilst the amplitude variation and phase excursions caused by transistor junction heating are reduced by the application of pre-pulse bias.
- Centre Frequency : 5.68Ghz & 5.72GHz
- Peak Output Power : 300W CW, 400W @ 5% duty
- Full Power Bandwidth: 40MHz min
- 3dB Power Bandwidth : 200Mhz typ
- Input Power for Rated Output : 0dBm nom
- Absolute max input Power : +15dBm (CW)
- Duty Cycle : 5% min to CW according to cooling system
- Input Signal Characteristic : CW or Pulsed
- Input Pulse Width : 200uS max
- Pulse Repetition Frequency : 5KHz max
- RF Output Stability in Pulse :0.2dB/10uS max, 0.8dB/200uS max @ peak O/P
- RF Output Phase Stability in Pulse : 1 degree max
- Harmonics: -40dBc max
- Non Harmonic Spurious Output : >80dBc
- Input Return Loss : 14dB min
- Output Return Loss : 18dB min
- Noise Figure : 6dB typ
- System Power Supply : Mains AC230V 1-phase
- Pulse control rise time (0-100% RF) : 5uS max
- Pulse control fall time (100-0% RF) : 5uS max
- RF Rise/Fall time : 100nS max
- TTL Pulse Control Signal : TTL HIGH = amplifier biassed to class A
- TTL Enable Signal (remote control) : TTL HIGH = amplifier ACTIVE
- Amplifier Dimensions (LWH) : 19" x 3U x 550mm 20Kg nom. Rack or bench top style chassis
- Power Supply Dimensions (LWH) 19" x 1U x 350mm (2Kg nom) 24V DC 50A typ (CW)
- Operating Temperature : 0 to 50C ambient
- Storage Temperature : -20 to 85C
2. RF output Variation in PulseThe above specifications apply when the amplifier is operated in saturation. Reduced RF output levels will result in correspondingly increased amplitude variation. It may be necessary to increase the TTL control to RF pulse delay to achieve optimum performance.
[caption id="attachment_2428" align="aligncenter" width="623" caption="Typical amplitude variation during pulse"][/caption] 3. Power Consumption The primary power input demand will be a function of the duty cycle. 110V and 230V versions are available – please specify when ordering. 4. Pulse Control Rise & Fall Time This is the period of transition between standby & active states. During the standby state the amplifier is disabled drawing minimal power, and can not amplify an RF signal. In response to a TTL (high) command, the amplifier switches to an active state with full DC bias, and is able to amplify a pulse. The duration of this transition is the Pulse Control Rise Time. At the end of the pulse the amplifier may be reverted to the standby state. The duration of this transition is the Pulse Control Fall Time. Note that the application of RF signals during these transitions will result in a distorted output. 5. RF Rise & Fall Time The RF rise/fall times are for a pulsed RF signal, with the amplifier stabilised in class A in response to TTL pulse-control signal. 6. TTL Pulse Control Signal The TTL pulse control line is AC coupled to prevent accidental application of CW RF input signals. 7. Test Data Test data for operation under specific duty conditions (pulse width & frequency) can be provided on request. Otherwise, test data under maximum duty conditions is provided. Signal Interfaces
- RF Input & Output: N type female panel jack
- TTL Enable: BNC female panel jack
- TTL Pulse control: BNC female panel jack
- Signals: 15 way D-type
- Dimensions (LWH): 19” x 3U x 550mm. Rack or bench top style chassis
- Weight: 20Kg nominal
The front panel mountings should not be used to support the entire weight of the amplifier when mounted in a 19" rack. The side extrusions accept M5 captive nuts, which should be located at the rear of the unit to provide additional support. Alternatively, the amplifier should be rested on a tray within the rack.
Front Panel Controls & Indicators
- Main power keyswitch Initialises unit & activates cooling system.
- Amplifier Enable Switch Illuminated push switch turns RF amplifier module on.
- PSU status indicator Displays status of AC/DC convertors.
- RF status indicator Shows presence of RF at output port
- TTL status indicator Shows presence of TTL-high enable signal
- Reflected power indicator Shows reflected power in excess of 200W
- Over temperature indicator Shows amplifier shut-down due to over temp.
- Output Power Meter Digital LED meter reading peak forward output power in watts
- (Limited accuracy where prf <10Hz or PW <1uS)
- TTL RF On/Off Status: High = ON
- Over Temp Status: High = Alarm
- VSWR Status: High = Alarm
- PSU Status: High = OK
- Forward Power Detector Output: +5V nom @ Peak RF O/P
- Detector Dynamic Range: 15dB min
- Operating temperature range: 0 to 50C ambient
- Storage temperature range: -20 to 85C
Amplifying a Pulsed RF Signal It is necessary to synchronise the RF pulse with the TTL pulse control signal. This is accomplished using two square wave pulse generators capable of the desired PRF, one as master the other as slave. The slave is configured to trigger a pulse from an RF source, the master to output the TTL pulse control signal to the amplifier and after the required delay (pulse control rise time), trigger the slave.
For SMR20 specifications & function refer to the operating manual or to online information at: http://www2.rohde-schwarz.com/file_3894/smr_20-40%20e03.pdf[caption id="attachment_2288" align="aligncenter" width="600" caption="Fig 1 - Using external pulse generators with an SMR20 Rohde & Schwarz source"][/caption]
NB. It is not necessary to program a delay between the end of the RF pulse and the TTL pulse control signal.
[caption id="attachment_2438" align="aligncenter" width="366" caption="Fig 2. Typical pulse timing for 10uS RF pulse"][/caption] Deliverables Each amplifier is supplied packed in a purpose designed carton containing:
- Pair of keys for front panel keyswitch. These are uncoded and factory replaceable.
- Pair of front panel handles with fixing screws. These are removed for transit.
- Mains power cable 2m.
- Operating manual with test data.