AT 490 – User manual Digital attenuator DC-4GHz, 90
Contents
1. RNE LABS AT 490 User manual O E E AT490 4 igi Ghz 90 dB digital attenuator i Digital attenuator DC 4GHz 90 dB Copyright ORMELABS C 2013 http www ormelabs com ORMNELABSS AT 490 User manual 1 Technical features e 0 to 91 dB using 1 dB steps 2 digits LCD display 9 points RS232 interface e Frequency range 100kHz to 4 GHz e Precision at 25 C 0 15 dB 0 3 dB 3 value 16 91 dB 0 3 dB 5 value compared to insertion loss e Insertion loss lt 6 dB at 1 GHz lt 11 dB at 4 GHz e Max power 25 dBm 0 1 W e Supply 2 AA LRO6 batteries e Autonomy gt 10 days 250h in operation gt 1 yr in standby attenuation not maintained e External supply 7 15 V dc lt 10 mA e P1dB typ 25 dBm 0 5 4 GHz e IP3 gt 32 dBm 0 5 4 GHz e Temperature range 0 70 C except batteries e 75 Q version available ref AT490 75 in this case frequency range is limited to 1MHz 2 GHz Chi Start 10 kHz Pwr 10 dBm Bw 10 kHz Stop 4 GHz Fig 1 typical insertion loss ORMNELABS AT 490 User manual 2 Operation Figure 2 explains the functions of the different keys and connectors of the instrument The On Off button allows to turn on or off the instrument In this last case after turning off the instrument the last attenuation value is stored in EEPROM memory but is not maintained The attenuation actually present between ports is und2. to 70 C and in a clean and dry environment free from dust and moisture Nevertheless the performances are guaranteed for a temperature of 25 C 2 C Storage is possible in a range of 40 C to 80 C excluding battery After transportation or storage one must take into account an acclimatization period of about 1 hour before turning on in order to prevent any risk of condensation or frost The instrument should not be used in explosive environment or submitted to aggressive chemical influence Warranty Ormelabs guarantees that the products manufactured comply with the specifications listed provided they have not undergone any change or transformation and they are normally used and maintained The obligation of Ormelabs expires one year after delivery and is limited to repair or replacement free of charge if the unit is defective by revealed under the only opinion of Ormelabs The unit must be returned in its original packaging which ensures maximum protection Damage during transit due to inadequate packaging are not within the scope of the warranty ORMNELABS AT 490 User manual 5 Remote operation The serial communication link works without any particular protocol It is hence recommended to add a small delay routine after each command sent in order to allow the instrument to treat the instruction before sending a new instruction string Typical required delay is 10 ms The commands are sent to the inst
3. a voltage source varying between 7 and 15 V de witha supply current of about 8 to 10 mA The connection polarity is as follows Lo The battery compartment has 4 battery places for AA LR6 type battery The instrument only needs 2 batteries for normal use the ones indicated on fig 2b The 2 remaining places can be used to store spare replacement batteries Rechargeable batteries can be used instead of standard ones but will not be charged by connecting an external mains power adapter For an extended time storage of the instrument it is recommended to remove the batteries of the instrument or to put them in the storage batteries compartments EE ee eee z ee ee a i i hun i i i a 7 i ORMNELABS AT 490 User manual 4 Security This instrument is build and tested to fit the norms materialized by the European marking visualized by the CE logo shown on the instrument The instrument should not be used and its batteries should not be removed if it does not seem to present the security conditions required as to say If instrument shows visible damages If some parts have been detached from the main unit If it does not work properly After an extended storage period or after transport is harsh conditions wet environment or outdoor unadapted packaging Its operation is expected in laboratory or at least indoors in a temperature range extending from 0 C
4. efined and may vary a lot with frequency Display Increase attenuation value RF In out Decrease attenuation value When the instrument is in operation turned on the supply current is several milliamps during 2 seconds and then falls down to a hundred microamps afterwards what allows to let the instrument in active state for quite a long period without discharging the batteries too much For an even longer operation period it is recommended to use an external power adapter Buttons and allow to decrease or increase the attenuation value in the range from 0 to ORMNELABS AT 490 User manual 3 91 dB using 1 dB steps The real attenuation value between the 2 SMA ports will be the sum of the insertion loss at 0 dB see fig 1 and of the displayed value A long press on one of the 2 buttons allows a fast automatic increase or decrease At turn off the last attenuation value is memorized The RS232 connector allows remote operation of the instrument through use of a computer The serial communication link uses a data rate of 9600 bps 8 data bits 1 stop bit and no parity This connector uses and accepts max voltages of 12 V according to RS232 protocol and can hence be connected to the COM port 1 or 2 of a PC compatible computer See chapter remote operation for details about the communication protocol and remote commands The supply connector accepts
5. rument by lines with characters ASCII codes ranging from 20 dec to 127 dec and terminated by an end of line sequence constituted of the CR 13 dec character and the LF 10 dec character Each line should only contain one command The available commands are the following ones ATT val Specifies the attenuation value in dB The value should be an integer between 0 and 91 ATT Asks for actual attenuation value The instrument returns a string with the following format lt value gt lt CR gt IDN Asks for instrument identification string The instrument answer has the following structure AT490 ORMELABS Rev 2 01 S N 30101 which indicates successively the instrument type the manufacturer name the firmware revision number and the serial number of the instrument Error messages Syntax error Sent when the command string does not correspond to any known instruction Bad parameter sent when a command is recognized but the parameter exceeds the allowed range String too long sent when the instrument detects a buffer overrun which occurs when the transmitted string exceeds the internal buffer capacity ORMNELABS AT 490 User manual 6
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