Model 3301B Active Rod & Field Antenna User Manual
Contents
1. 16 5 2 Electrical Specifications da cine dieta ete dd i rede nea 16 5 3 Mechanical SpecifiCatiOns 17 6 0 Principles Of Operation 4 4 nentes nnns sentent nene 19 DescriptiOR taii sip etat oe ees 19 GAFON PNE 23e mete m etc ce ec etre nis eder 19 6 3 Internal Options tritt Pe Eee de ef ene a te a eitis 20 6 3 1 Factory Settings etie cesta SEM bh eoe 21 6 3 2 Proper Selection of Internal Attenuation 222 2 2 4400 22 ML e tisha uaa CS D E 23 7 1 Voltage Selectable Battery Charger 23 FONT M 23 721 2 Specifications ae ee aa 24 ke Battery bow iet loud eee nete einen 24 24 8 0 5 ie er pe GE ee eri a Periit a aie 27 MESI 27 8 2 High Sensitivity Readings sse ener nnne nnne nre 28 Archived 3 18 10 9 0 Lheoty Of Operation etae o I Akal n Ee cas i P tee e RE Du 29 9t Thie ROG deinde cea a eoe 29 9 2 The on ntt a o t a ctae ee e bed aed 30 10 0 Factor eei e emite rele oeste cde etel 33 11 0 Antenna Impulse 35 11 1 I2. 52 Typical Roll Off Curves for Switches and 4 53 Typical Roll Off Curves 41 Rod Antenna 0 dB Attenuation 54 Typical Roll Off Curves 41 Rod Antenna 10 dB Attenuation 55 Typical Roll Off Curves 41 Rod Antenna 30 dB Attenuation 56 Archived 3 18 10 Safety Symbol Definitions This product and related documentation must be reviewed for familiarization with safety markings and instructions prior to operation of the product Safety Symbol Definition REFER TO MANUAL When the product is marked with this symbol refer to the instruction manual for additional information If the instruction manual has been misplaced go to www ets lindgren com for downloadable files or contact ETS Lindgren customer service CAUTION CAUTION Denotes a hazard Failure to follow instructions could result in minor personal injury and or property damage Text that follows the symbol will provide proper procedures General Safety Considerations Safety Symbol Definition v WARRANTY BEFORE SERVICING CONTACT ETS LINDGREN 1 512 531 6400 Servicing or modifying the unit without ETS Lindgren authorization may void your warranty If an attempt to service the unit must be made disconnect a
3. 1 meter The next is the measured capacitive loss at the front of the unit of about 4 dB Then there is the gain of the amplifier itself 15 dB Finally 6 dB is required to conjugate match the output to 50 ohm The antenna factor is the sum of these factors A typical result might be 6 dB Rod Normalization 4 dB Capacitive Loss 15 dB Preamlifier Gain 6 dB 50 ohm Matching Loss 1 dB Gain Over Field Strength or Antenna Factor of 1 dB The Antenna Factor 33 Archived 3 18 10 This page intentionally left blank 34 The Antenna Factor Archived 3 18 10 11 0 Antenna Impulse Response The Model 3301B is designed and optimized for the measurement of CW type signals However this unit is fully capable of dealing accurately with impulsive type signals with some special considerations This section guides the user who intends to use the Model 3301B to measure impulsive signals By following the provided guidance accurate measurements of impulsive signals may be performed The Model 3301B may be used to measure the important characteristics of an impulse signal that fall within its bandwidth and dynamic range However the measurement of impulsive signals requires some special cautions to avoid saturation of the antenna amplifier 11 1 Impulse Characteristics Before discussing the Model 3301B response to impulse signals a brief review of the nature of impulse signals is appropriate For our purposes we will co
4. 10 internal attenuators are provided With the attenuators the Model 3301B is usable in fields of up to 22 V m Therefore the dynamic range of the unit is expanded to 145 dB A saturation indicator is provided to alert the user to the need for using the internal attenuators The Model 3301B is designed to provide the user with an extremely versatile measurement tool The flat antenna factor extreme sensitivity and ultra wide dynamic range make it a state of the art sensing instrument Introduction 7 Archived 3 18 10 This page intentionally left blank 8 Introduction Archived 3 18 10 2 0 Receiving Your Order 2 1 Unpacking and Acceptance Step 1 Upon delivery of your order inspect the shipping container s for evidence of damage Record any damage on the delivery receipt before signing it In case of concealed damage or loss retain the packing materials for inspection by the carrier Step 2 Remove the product from its shipping container s Save the container s and any protective packing materials for future use Step 3 Check all materials against the packing list to verify that the equipment you received matches what was ordered If you find any discrepancies note them and call ETS Lindgren Customer Service for further instructions Make sure you are satisfied with the contents and condition of your order prior to placing the product into service 2 2 Service Procedures To return a system or system c
5. 18 10 TYPICAL ROLL Orr CURVES 41 ROD ANTENNA 0 DB ATTENUATION _ gt Generator output 250 mV 15 1 22 kHz ROLL OFF 1 9 kHz ROLL OFF 10 4 SI 170 Hz ROLL OFF T 0001 ANTENNA FACTOR dB FREDUEMCY Mhz 54 Data and Illustrations 100 Archived 3 18 10 ANTENNA FACTOR dB TYPICAL ROLL Orr CURVES 41 ROD ANTENNA 10 DB ATTENUATION gt Generator output 250 mV 30 22 kHz ROLL OFF 25 ER 1 9 kHz ROLL OFF V TT 10 0001 001 00 FREQUENCY MHz Data and Illustrations 55 Archived 3 18 10 TYPICAL ROLL Orr CURVES 41 ROD ANTENNA 30 DB ATTENUATION ANTENNA FACTOR dB a Generator output 8000 mV 22 kHz ROLL OFF 45 LHMI 1 9 2 ROLL OFF 170 Hz ROLL OFF N b Mhz 56 Data and Illustrations 00
6. 3 dB roll off point Saturation Level e 0 7 V m narrowband without attenuation and at the low gain setting e 22 V m with 30 dB of internal attenuation selected e 63 dBuV m MHz broadband saturation level Minimum Discernible Signal See data graphs included with manual For best sensitivity the unit should be in the low gain setting with all internal attenuation off Dynamic Range e 115 dB at mid band 1 MHz e 145 dB with the use of the internal attenuators Specifications 15 Archived 3 18 10 Saturation Indicator Impulse Response The saturation indicator will properly indicate saturation for pulsed signals which fall within the following boundaries 1 The product of the pulse width to pulse repetition rate must be greater than 003 2 The pulse repetition rate must be less than value listed for the applicable duty cycle See the following Table of Acceptable Pulse Repetition Rates 5 1 1 Table of Acceptable Pulse Repetition Rates Duty Cycle 10 20 30 40 50 60 70 80 90 5 2 Electrical Specifications Maximum PRF 19 7 MHz 14 0 MHz 9 2 MHz 5 6 MHz 420 0 kHz 130 0 kHz 87 0 kHz 57 0 kHz 30 0 kHz Input Impedance The input impedance determines the low frequency roll of point Depending on the low frequency roll off selected the input impedance is gt 20 megohms 1 megohm or 100 kilohm Output Impedance 50 ohm nominal Sat
7. IEC 801 2 Level 2 4 8kV IEC 801 3 Level 2 3V m IEC 801 4 Level 2 5 I O 1kV AC AUTHORIZED SIGNATORIES T i A Bruce Butler General Manager Jam sencik Engineering Mgr Charles Garrison Quality Assurance Date of Declaration December 10 1996 The authorizing signature on the EC Declaration of Conformity document authorizes EMC Test Systems L P to affix the CE mark to the indicated product CE marks placed on these products will be distinct and visible Other marks or inscriptions liable to be confused with the CE mark will not be affixed to these products EMC Test Systems L P has ensured that appropriate documentation shall remain available on premises for inspection and validation purposes for a period of no less than 10 years European Community Declaration of Conformity 45 Archived 3 18 10 This page intentionally left blank 46 European Community Declaration of Conformity Archived 3 18 10 Appendix C Data and lllustrations PERIODIC RECTANGULAR PULSE TRAIN TIME SPECTRUM OF RECTANGULAR PULSE Amplitudes and phases of an infinite number of harmonics are required to fully describe the envelope ae SPECTRAL LINES ANTENNA BANDWIDTH HIGH LOW FREQUENCY FREQUENCY LIMIT LIMIT 2 3 T T A FREQUENCY f Data and Illustrations 47 Archived 3 18 10 ALTERING PULSE WiDTH PULSE REPETITION RATE The following figures A D depict the effect of altering eithe
8. Two grounding strips are provided on top of the unit These are intended to attach to a counterpoise which is provided with the unit To assemble the unit first touch the two metal counterpoise mounting strips located on top of the antenna chassis then remove the two screws from each strip The unit is meant to be under the counterpoise In this way the body of the unit does not intrude into the field being measured Open the counterpoise and attach it to the mounting strips using the screws that were just removed Next the rod should be attached to the fitting at the center of the unit through the hole in the counterpoise The rod should then be extended to 41 The output of the unit should be connected to a 50 ohm receiver spectrum analyzer or RF voltmeter The technician should remove the ESD wrist strap at this time The unit is activated by pressing in the power switch on the front panel The switch will turn to green and the battery low power indicator light will come on Should the indicator light not come on the level of the battery charge should be checked Finally the state of the gain switch should be checked It is anticipated that in most applications the low gain setting will be used The unit housing hangs under the counterpoise with the antenna rod passing through an opening in the counterpoise It should be noted that the brass tripod mounting bracket on the bottom of the unit is not a ground location The unit must be at
9. an extremely low 30 Hz In fact artificial limiting was introduced to protect the unit in situations where overloading from power frequencies would be a problem The low frequency roll off switches in to unit allow the user to set the low frequency cutoff according to the particular testing needs The second stage is made up of three exceptionally high quality transistors The first is configured common emitter for voltage gain and to give a precise 180 degrees phase reversal for the output The second two transistors for a Darlington pair to drive the 50 ohm output The output of this stage is then DC isolated matched to 50 ohm and passed through a common mode choke The result is that cable VSWR and common mode noise problems are minimized The dynamic limits of the Model 3301B are set by the amplifier Sensitivity is determined by the noise developed in the first stage The ultimate limit on sensitivity is determined by the thermal noise generated by the input impedance The impedance presented to the amplifier by the rod is almost entirely capacitive A 41 rod typically presents an impedance of about 12 pF Therefore the input impedance presented to the amplifier will decline with increasing frequency At the low frequencies where the input impedance is high the thermal noise generated by this impedance will also be high If the input impedance of the amplifier is lowered to reduce thermal noise then the rod will be loaded down and lose sen
10. be critical to ensure measurement accuracy Also of concern is the contribution of edge effects from the vestigial ground plane Most theory is developed on the assumption of one infinite ground plane How using a small vestigial ground plane or counterpoise affects the theory has not been well studied to date Even more complicated is the effect of this vestigial ground plane when the unit is used in a screen room with the ground planes on all sides In practice the best results are obtained by tightly typing the counterpoise to the screen room through an ultra low impedance ground strap This at least assures that at the lower frequencies all of these surfaces are at an equal potential 9 2 The Pre Amplifier 30 The Model 3301B pre amplifier is designed in two stages The first stage provides impedance transformation and current gain The second stage provides voltage gain and impedance mating on a 50 ohm output The first stage of the pre amplifier contains an n channel JFET and an NPN bipolar silicon transistor Through the use of extremely precise layout techniques careful parts selection and feedback to virtually eliminate the Miller effect the total input capacitance is kept extremely low This low capacitance in turn allows for an extremely high input impedance Theory of Operation Archived 3 18 10 It is the output impedance which determines the effective low frequency cutoff of the unit The Model 3301B is still usable at
11. in use the antenna should be connected to the battery charger in trickle charge mode Charging time is approximately eight hours when batteries are completely discharged The antenna is not designed to operate using the battery charger as a power source Batteries should provide power to the amplifier for approximately 16 hours before recharging is required Always remove main power before opening the housing Power Circuitry 23 Archived 3 18 10 The battery charger is protected against overcurrent by a 200 mA 250 VAC time delay fuse If it becomes necessary to replace the fuse use a fuse of the same type and rating to maintain safe operations The fuse is accessible by removing the two Phillips head screws on the underside of the unit The output of the battery charger is protected against overcurrent conditions by use of fold back circuitry 7 1 2 Specifications Input voltage 115 230 VAC selectable Input frequency 50 60 Hz Input power 20 VA max Protection class Class double insulated Input fuse rating 200 mA time delay type 5 x 20 mm Input power connection IEC 320 power inlet Output voltage 12 VDC 13 5 15 VDC Output current 350 mA Safety approvals TUV CSA 7 2 Battery Low Indicator If the Battery Low Power On indicator on the front of the unit does not illuminate when the power switch is on the batteries should be recharged 7 3 Fuses Located insi
12. provides additional output power for test situations that require additional output Principles of Operation 19 Archived 3 18 10 SATURATION INDICATOR The Saturation indicator is located above the power indicator Readings should not be taken when the unit indicates it is in saturation If this occurs input to the unit should be reduced by placing the unit in the low gain mode or by switching in internal attenuation Impulsive type signals present a particular problem in that they may put the unit into a non linear region without triggering the saturation circuit When dealing with impulsive type signals the 63 dBu V m MHz should be strictly observed If a signal exceeds this limit the internal attenuation should be applied The limiting factor on handing impulsive signals is the unit output capability Therefore once the internal attenuators are engaged most higher impulsive signals may be measured For example with the 30 dB attenuator engaged a 93 dBuV m MHz may be measured BATTERY CHARGING PORT A Battery Charging port is provided for easy recharging of the sealed lead acid batteries internal to the unit To charge the unit turn off the power switch and plug in the battery charger The charging circuit will not charge the batteries when the unit is on 6 3 Internal Options 20 Internal to the unit is a 4 switch bank of slide switches These switches control the internal attenuation and the low frequency roll off To a
13. the antenna must provide the vector sum of all the frequency domain spectral lines Therefore extra care must be taken to protect the antenna amplifier from saturation when making impulse measurements in the frequency domain The internal attenuators in the Model 3301B allow it to overcome many of the barriers which earlier units presented to such measurements These attenuators allow the user to safely keep the amplifier in its linear region The saturation indicator in the Model 3301B will provide an accurate warning of impending saturation provided two conditions are met First the product of the pulse width to pulse repetition rate must be greater than 0 003 Second the pulse repetition rate must be less than the value listed in Table of Acceptable Pulse Repetition Rates page 16 If an impulse falls outside of these two parameters the saturation indicator will not accurately warn of saturation However the antenna will accurately handle the impulse signal within its bandwidth and dynamic range limitations The reasons for these requirements are two engineering trade offs which must be made and are explained in the next two sections 11 2 Pulse Desensitization 36 The Model 3301B saturation indicator operates by creating a DC level on a capacitor feed through a rectifying diode This DC level is then compared to a second DC level which is set at the amplifier 1 dB compression point This circuit works extremely well for CQ t
14. 3301B the various stages are AC coupled Furthermore to allow the extremely broad bandwidth of the unit large value low impedance capacitors are used to provide the AC coupling When a pulse passes through these capacitors a charge is developed After the pulse passes this charge drains through the associated resistance to ground at an established RC constant However if the next pulse occurs before the residual charge has fully discharged then a residual DC bias is created This bias artificially alters the DC level on the saturation indicator comparison capacitor causing it to fail to properly indicate saturation Again in this region the user must closely monitor the antenna output for saturation Antenna Impulse Response 37 Archived 3 18 10 This page intentionally left blank 38 Antenna Impulse Response Archived 3 18 10 12 0 Calibration Procedure ETS Lindgren recommends the equivalent capacitance method of calibration for the Model 3301B active rod antenna To check the calibration a Model 3301B calibration test fixture is required This fixture contains a resistive T and a capacitor The T allows for accurate reading of the input to the fixture The capacitor feeds the amplifier through the same impedance as the 41 rod presents to it The result is a simple yet extremely accurate calibration Periodic checks of performance are recommended To calibrate the unit simply attach the calibration fixture and groun
15. 5211 amp 5220 be 1 free from defects in material manufacturing workmanship and title and 2 conform to the Seller s applicable product descriptions and specifications if any contained in or attached to Seller s quotation If no product descriptions or specifications are contained in or attached to the quotation Seller s applicable product descriptions and specifications in effect on the date of shipment shall apply The criteria for all testing shall be Seller s applicable product specifications utilizing factory specified calibration and test procedures and instruments All product warranties except the warranty of title and all remedies for warranty failures are limited in time as shown in the following table Product Warranted Duration of Warranty Period Standard EMCO Brand Products Excluding 5211 amp 5220 2 Years Any product or part furnished to Buyer during the warranty period to correct a warranty failure shall be warranted to the extent of the unexpired term of the warranty applicable to the repaired or replaced product The warranty period shall commence on the date the product is delivered to Buyer however if Seller assembles the product or provides technical direction of such assembly the warranty period for such product shall commence on the date the assembly of the product is complete Notwithstanding the foregoing in the event that the assembly is delayed for a total of thirty 30 days or mor
16. Archived 3 18 10 Model 3301B Active Rod amp Field Antenna User Manual sad ENT S om LINDGREN An ESCO Technologies Company Archived 3 18 10 ETS Linggren L P reserves the right to make changes to any products herein to improve functioning or design Although the information in this document has been carefully reviewed and is believed to be reliable ETS Lindgren does not assume any liability arising out of the application or use of any product or circuit described herein nor does it convey any license under its patent rights nor the rights of others All trademarks are the property of their respective Owners Copyright 2000 2006 by ETS Lindgren L P All Rights Reserved No part of this document may be copied by any means without written permission from ETS Lindgren L P Trademarks used in this document The ETS Lindgren logo is a trademark of ETS Lindgren L P Revision Record MANUAL 3301B Part 399046 Rev Revision Description Date A J Initial Release edits updates Through September 2003 K Edited rod capacitance template format November 2006 Internet Address http Awww ETS Lindgren com USA 1301 Arrow Point Drive Cedar Park TX 78613 USA Tel 1 512 531 6400 Fax 1 512 531 6500 Email info ETS Lindgren com Finland Mekaanikontie 1 27510 Eura Finland Tel 358 2 838 330 Fax 358 2 865 1233 Email info ET
17. S Lindgren eu com Japan 4 2 6 Kohinata Bunkyo ku Tokyo 112 0006 Japan Tel 81 3 3813 7100 Fax 81 3 3813 8068 Email info ETS Lindgren co jp China B507A Technology Fortune Center No8 Xue Qing Road Haidian District Beijing Postcode 100083 China Tel 86 010 827 30877 Fax 86 010 827 55307 Email info ETS Lindgren net Archived 3 18 10 Table of Contents Safety Symbol General Safety Considerations pU 7 2 0 Receiving Your Order 9 2 1 Unpacking and 9 2 2 Service Procedur s 9 3 0 e IP Ra 11 3 1 Maintenance 11 3 2 Replacement and Optional 2 11 4 0 Standard 13 Leer m MEER 13 5 0 SpecIfICatiOris ceti eb este etu tum dtu t d red tette 15 5 1 Operational 15 5 1 1 Table of Acceptable Pulse Repetition
18. also raised by 10 dB At 2 2 V m with the 10 dB attenuator active the saturation indicator light will again come on This indicates a need to switch the 30 dB attenuator on in place of the 10 dB attenuator The 30 dB internal attenuator will allow the unit to maintain calibration while measuring field strengths up to 22 V m Again the unit retains 115 dB of dynamic range Both the maximum reading before saturation and the minimum discernible signal are raised 30 dB above their 0 dB attenuation values When using either of the attenuators make sure to add the attenuation to the antenna factor for accurate readings Also note that if both attenuator switches are used the resulting attenuation is approximately 31 dB and not 30 dB It is unwise to use attenuation to measure very low field strengths When the field strength falls below the minimum discernible signal inaccurate field strength measurements will result Both of the internal attenuators have a 1096 tolerance so they should be calibrated before being used in critical applications A warning about the internal 30 dB attenuator With the 30 dB attenuator active the unit resonates at 30 MHz Therefore the unit should not be used above 15 MHz with the 30 dB attenuator active The usefulness of the internal attenuators for impulse response testing is discussed in Antenna Impulse Response on page 35 Principles of Operation Archived 3 18 10 7 0 Power Circuitry The Mod
19. and Seller s sole liability for claims based on failure of the products to meet any warranty whether the claim is in contract warranty tort including negligence and strict liability or otherwise and however instituted and upon the expiration of the applicable warranty period all such liability shall terminate IN NO EVENT SHALL SELLER BE LIABLE TO BUYER FOR ANY SPECIAL INDIRECT INCIDENTAL OR CONSEQUENTIAL DAMAGES OF ANY KIND ARISING OUT OF OR AS A RESULT OF THE SALE DELIVERY NON DELIVERY SERVICING ASSEMBLING USE OR LOSS OF USE OF THE PRODUCTS OR ANY PART THEREOF OR FOR ANY CHARGES OR EXPENSES OF ANY NATURE INCURRED WITHOUT SELLER S WRITTEN CONSENT DESPITE ANY NEGLIGENCE ON BEHALF OF THE SELLERIN NO EVENT SHALL SELLER S LIABILITIES UNDER ANY CLAIM Warranty Policy for Standard EMCO Brand Products Archived 3 18 10 MADE BY BUYER EXCEED THE PURCHASE PRICE OF THE PRODUCT IN RESPECT OF WHICH DAMAGES ARE CLAIMED This agreement shall be construed in accordance with laws of the State of Illinois In the event that any provision hereof shall violate any applicable statute ordinance or rule of law such provision shall be ineffective to the extent of such violation without invalidating any other provision hereof Any controversy or claim arising out of or relating to the sale delivery nondelivery servicing assembling use or loss of use of the products or any part thereof or for any charges or expenses in connection therewith shall be se
20. ccess the switch bank hold the unit upside down and remove the bottom cover With the unit upside down and the front panel to the left e top switch closest to the fuse holder adds 10 dB of internal attenuation e The next switch down adds 30 dB of attenuation e third switch sets the low frequency roll off of 3 dB down at 1 9 kHz e fourth switch sets the low frequency roll off of 3 dB down at 22 kHz Principles of Operation Archived 3 18 10 The antenna rod terminal is directly connected to the high CAUTION impedance gate of a field effect transistor Do not lift the antenna by the rod or touch it before properly grounding out to the unit case Accumulated static charge on test personnel may damage the FET If the antenna is used in a location where static discharges are likely to be prevalent attach a grounding clip between the chassis and the antenna rod while the antenna is being set up to prevent damage to the amplifier circuitry The following diagram reflects the sequence of functions as they are connected on the board FUSE 10 dB Atten 30 dB Atten i 1 9 kHz LF Roll Off 22 0 kHz LF Roll Off o tc 10 dB 10 Input Attenuator 30 dB 10 Input Attenuator 1 9 kHz Low Frequency Roll Off 22 0 kHz Low Frequency Roll Off Moving any switch to the extreme left toward the center of the unit activates the i
21. d it to the Model 3301B housing through one of the counterpoise mounting holes Place a signal source on one leg of the fixture and a receiver on the other leg Then terminate the output of the unit with 50 ohms Read the input signal strength The input signal strength measured through the calibration fixture must have 11 dB added to it The 11 dB is composed of 6 dB required to normalize the rod to 1 meter and 5 dB of signal loss through the resistive divider in the T After the input is read move the receiver cable to the output of the unit and place a 50 ohm load on the now open leg of the calibration fixture Read the unit output The antenna factor is the input plus 11 dB minus the output both readings assumed to be logarithmic ETS Lindgren recommends the following input voltage levels for field calibration Voltage Internal Attenuation 250 mV 0 dB 450 mV 10 dB 8V 30 dB EXAMPLE Suppose a reading is taken with a 1 MHz signal input to the calibration fixture The input is read as 50 dBuV and the output is read as 59 dBuV The antenna factor is then the input plus 11 dB minus the output of 50 dBuV 11 dB 59 2cB Calibration Procedure 39 Archived 3 18 10 This page intentionally left blank 40 Calibration Procedure Archived 3 18 10 Appendix A Warranty Policy for Standard EMCO Brand Products SCOPE AND DURATION OF WARRANTIES Seller warrants to Buyer that the Standard EMCO Brand Products Excluding
22. de the Model 3301B are two fuses one for each battery To replace the fuses Disconnect the power cord and charger before opening the unit m Replace the fuses with either Type AC size 0 5 AMP fast acting or 5 x 20 mm fuses 1 Usea Phillips head screwdriver to carefully remove the screws around the edge of the bottom panel Lift the bottom panel off the unit 24 Power Circuitry Archived 3 18 10 2 Locate the two fuses in their holders mounted on the circuit board and replace the fuses 3 Replace the bottom panel of the unit and reinstall the screws Power Circuitry 25 Archived 3 18 10 This page intentionally left blank 26 Power Circuitry Archived 3 18 10 8 0 Setup and Use The Model 3301B is designed for ease of use and is designed for five accurate reading types in a variety of test environments However precision measurements require an understanding of the test parameters that will adversely affect test results No single test instrument can insure accurate results For best results the user should become thoroughly familiar with both the practical and theoretical operating parameters for this unit 8 1 Setup Before beginning the setup procedure make sure that the technician is completely grounded using an ESD wrist strap at an ESD protective workstation for protection of the antenna FET Make sure antenna power is off The Model 3301B is quite sensitive to test setup and proper use
23. del 4 TR Constructed of linen phenolic and delrin designed with an adjustable center post for precise height adjustments Maximum height for the 4 TR is 2 0 m 80 0 in and minimum height is 94 cm 37 0 in This tripod can support up to an 11 8 kg 26 0 Ib load e Model 7 TR Allows several different configurations including options for manual or pneumatic polarization The 7 TR provides increased stability for physically large antennas The unique design allows for quick assembly disassembly and convenient storage Quick height adjustment and locking wheels provide ease of use during testing This tripod can support a 13 5 kg 30 Ib load For the 7 TR series maximum height is 2 17 m 85 8 in with a minimum height of 8 m 31 8 in The 7 TR is constructed of PVC and fiberglass components Standard Configuration 13 Archived 3 18 10 This page intentionally left blank 14 Standard Configuration Archived 3 18 10 5 0 Specifications 5 1 Operational Specifications Frequency Range 30 Hz to 50 MHz maximum usable bandwidth Low Frequency Roll Off The low frequency roll off is switch selectable to be 3 dB down at 22 kHz 1 9 kHz or 170 Hz High Frequency Roll Off Antenna factor is 3 dB down at 30 MHz Antenna Factor See data graphs included with manual The calibration graphs were taken in the low gain setting Unless otherwise noted the low frequency roll off is set at the 170 Hz
24. e eighth wavelength At this point some resonance behavior is possible A rod that is electrically a half meter is one eighth wavelength at 75 MHz To keep the response of the unit linear and avoid resonance behavior the Model 3301B pre amplifier is limited to roll off before this frequency has been reached However this avoidance of possible resonance carries the penalty of 6 dB on the antenna factor Because field strength is measured as volts per meter the measurement must be normalized to 1 meter This means that 6 dB must be added to a reading taken with a half meter rod The second factor of concern is the impedance the rod presents to the measurement system The resistive component is non significant in this situation The controlling impedance is the capacitance of the rod to ground This capacitance may be calculated by the formula 55 63 h In h a h length of the rod in meters a radius of the rod in meters The natural logarithm of h over a is represented by In For the Model 3301B rod the capacitance is 10 picofarads pF This capacitance is significant because it combines with the total input capacitance of the amplifier to form a voltage divider It can quickly be seen that if the FET input capacitance and circuit stray total 10 pF there will be a 6 dB loss through this stray capacitance Even if the total input capacitance where reduced to 4 pF there would be 2 5 dB loss Theory of Operation 29 Arc
25. e from the date of delivery for any reason or reasons for which Seller is not responsible the warranty period for such product may at Seller s options commence on the thirtieth 30th day from the date such product is delivered to Buyer Buyer shall promptly inspect all products upon delivery No claims for shortages will be allowed unless shortages are reported to Seller in writing within ten 10 days after delivery No other claims against Seller will be allowed unless asserted in writing within thirty 30 days after delivery or assembly if the products are to be assembled by Seller or in the case of alleged breach of warranty within the applicable warranty period WARRANTY EXCLUSIONS Except as set forth in any applicable patent indemnity the foregoing warranties are exclusive and in lieu of all other warranties whether written oral express implied or statutory EXCEPT AS EXPRESSLY STATED ABOVE SELLER MAKES NO WARRANTY EXPRESS OR IMPLIED BY STATUTE OR OTHERWISE WHETHER OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR USE OR OTHERWISE ON THE PRODUCTS OR ON ANY PARTS OR LABOR FURNISHED DURING THE SALE DELIVERY OR SERVICING OF THE PRODUCTS THERE ARE NO WARRANTIES WHICH EXTEND BEYOND THE DESCRIPTION ON THE FACE HEREOF Warranty Policy for Standard EMCO Brand Products 41 Archived 3 18 10 Warranty coverage does not include any defect or performance deficiency including failure to conform to product descriptions o
26. el 3301B is powered by two 6 VDC sealed lead acid batteries A battery charger is supplied with the unit The battery charging port of the front of the unit allows for easy recharging of the unit Two internal fuses protect the unit from unintentional shorting 7 1 Voltage Selectable Battery Charger 7 1 1 Operation 0 The EMCO brand Voltage Selectable Battery Charger is solely intended for charging the sealed lead acid batteries found in EMCO products The battery charger is a means of providing the necessary charge voltage and current from either a 115 or 230 VAC 50 60 Hz source It is necessary to select the proper input voltage prior to connecting the battery charger to the power mains The voltage select switch is located adjacent to the power input receptacle To maintain safety requirements use the CSA certified power cord provided If it is necessary to provide other means of attaching the battery charger to the power mains it is required that a type HD 21 PVC cord or type HD22 rubber cord with a nominal cross section of 0 75 mm be used The battery charger provides both fast and trickle charge operation The charger handles switching from one charge mode to the other automatically The front panel indicator marked Fast Charge lights when the battery charger is in the fast charge mode When the Power On light is illuminated and the Fast Charge light is dark the battery charger is in the trickle charge mode When not
27. his page intentionally left blank 18 Specifications Archived 3 18 10 6 0 Principles of Operation 6 1 Description The ETS Lindgren Model 3301B electric field receiving antenna is composed of three principal sections a sensing rod a ground plane or counterpoise and a broadband high input impedance pre amplifier The rod and counterpoise function together as an electrically short antenna over ground plane The pre amplifier provides impedance transformation from the extremely high impedance at the base of the rod to the 50 ohms required by most receiving systems and provides power gain to allow the sensing of very low level signals 6 2 Front Panel On the front panel of the Model 3301B are the following Power switch e Gain switch Saturation indicator e Battery Low Power On indicator e BNC Output port e Battery Charging port POWER SWITCH The power switch is located on the lower right of the front panel Activating the power switch will turn on the Battery Low Power On indicator green BATTERY Low POWER ON INDICATOR The Battery Low Power On indicator is controlled by a voltage monitor circuit If the green indicator does not turn on or if it turns off during use the battery requires charging GAIN SWITCH In the middle left is the Gain switch which increases the voltage output of the gain stage in the amplifier by 10 dB However best sensitivity is achieved in the low gain setting The gain option
28. hived 3 18 10 Finally the interaction of the rod with the ground must be understood The theoretical understanding of the rod assumes that it operates in reference to an infinite ground at O Volt potential The closer the test situation is to this scenario the more accurate will be the readings A small vestigial ground is provided with the unit in the form of a counterpoise Care should be taken to reference this counterpoise to true ground The procedures for this are carefully explained in various standards If the counterpoise is not well grounded an impedance may build up through the cabling and other instrumentation Reading differences of as much as 20 dB can be found with ungrounded counterpoises This will be true for all rod antennas regardless of their design Another counterpoise problem is the potential for positive feedback Good amplifier design calls for the output to be 180 degrees out of phase with the output signal so that the shield current is in phase with the input If the shield and counterpoise are tied through the body of the unit then the counterpoise will receive some of this current If the counterpoise does not have an extremely low impedance to ground then this return current can drive a potential on the counterpoise in phase with the input resulting in errant readings The Model 3301B has an internal common mode choke to minimize the impact of an inadequate test setup However proper test configuration will always
29. ite bandwidth is required The lack of high frequency components shows up on the time domain as a rounding of sharp corners and a slowing of the rise and fall Antenna Impulse Response 35 Archived 3 18 10 In the same way the antenna will not efficiently pass spectral components that fall below its bandwidth For the Model 3301B the selected low frequency roll off will determine how wideband the response is The very low frequency components basically describe the flat top and bottom of the time domain pulse So when the waveform is band limited by the antenna the resulting waveform will have a decay constant returning the output to ground rather than maintaining a flat topped pulse A third phenomenon that occurs when measuring impulse type waveforms is that saturation of the amplifier is harder to detect By definition impulsive type signals spread their energy over many spectral components So when viewed in the frequency domain the energy demanded of the antenna amplifier may appear much lower than it actually is The energy demanded of the antenna amplifier to properly pass a pulse is not just the peak pulse in the frequency domain waveform but rather the sum of the energy contained in all the spectral lines By looking in the time domain it is easy to see that the amplifier must provide the energy to go from ground to the pulse peak almost instantaneously The impulse delivers all its frequency domain spectral components in phase So
30. ll electrical power prior to beginning Voltages exist at many points within the instrument that could if contacted cause personal injury Only trained service personnel should perform adjustments and or service procedures upon this instrument Capacitors inside this instrument may still be charged even when the instrument is disconnected from the power source ONLY QUALIFIED PERSONNEL should operate or service this equipment Archived 3 18 10 This page intentionally left blank vi Archived 3 18 10 1 0 Introduction The ETS Lindgren Model 3301B is a broadband high sensitivity electric field receiving antenna The Model 3301B is composed of a monopole rod antenna with a counterpoise and a broadband high impedance pre amplifier It is designed to provide reception of an electric field in a signal band without tuning or band switching from 30 Hz to 50 MHz The roll off points for the antenna factor are at 170 Hz and 30 MHz Between 250 Hz and 20 MHz the antenna factor is flat within 1 dB Despite the roll of the antenna factor the usable range is 30 Hz to 50 MHz The Model 3301B is designed for maximum sensitivity and dynamic range and is capable of sensing fields of 2 dBuV m at 1 MHz with a 1 kHz bandwidth However it will not saturate below a field strength of 0 7 V m As a result the unit boasts an extremely wide dynamic range of 115 dB nominal at mid band In addition at 10 and 30 dB
31. ment of the product or parts thereof by Seller under the warranty Seller does not warranty products of others which are not included in Seller s published price lists for shielding products and systems supplies and accessories BuvER s REMEDIES 42 If Seller determines that any product fails to meet any warranty during the applicable warranty period Seller shall correct any such failure by either at its option repairing adjusting or replacing without charge to Buyer any defective or nonconforming product or part or parts of the product Seller shall have the option to furnish either new or exchange replacement parts or assemblies Warranty service during the applicable warranty period will be performed without charge to Buyer within the contiguous 48 United States during Seller s normal business hours After the warranty period service will be performed at Seller s prevailing service rates Subject to the availability of personnel after hours service is available upon request at an additional charge For service outside the contiguous 48 United States travel and per diem expenses when required shall be the responsibility of the Buyer or End User whichever is applicable The remedies set forth herein are conditioned upon Buyer promptly notifying Seller within the applicable warranty period of any defect or nonconformance and making the product available for correction The preceding paragraphs set forth Buyer s exclusive remedies
32. mpulse 4 04 01 4 0 00 enne tnn nitentes nnne nes 35 11 2 Pulse i 36 37 12 0 Calibration 39 Appendix A Warranty Policy for Standard EMCO Brand Products 41 Scope and Duration 2 eene nennen 41 Waranty EXCUS OS c 41 Buyer s Bemedies es Aly 42 Appendix B European Community Declaration of Conformity 45 Appendix C Data and Illustrations 47 Periodic Rectangular Pulse Train sese eene 47 Spectrum of Rectangular 47 Altering Pulse Width Pulse Repetition Rate 48 Active Electric Field Antenna Calibration Fixture sse 49 Active Rod Antenna Calibration Setup 50 Typical Curves Minimum Discernible Signal at Various Bandwidths 51 Typical Attenuation Effect for Switches 1 2 0 400000 0 000
33. ndicated function Moving the switch to the extreme right toward the side of the unit deactivates that function The most commonly used configuration will have the 22 kHz roll off switch on and all other options off 6 3 1 Factory Settings The unit comes configured from the factory with the 22 0 kHz LF Roll Off set to on All other switches are off It is anticipated that the unit will normally be used with one of the roll off switches on Due to the abundance of low frequency ambient noise in most settings using the full bandwidth of the unit will make it very susceptible to saturation However when extremely low frequency measurements are required the unit is capable of providing these measurements Principles of Operation 21 Archived 3 18 10 If both roll off switches are simultaneously set in the on position the low frequency 3 dB roll of point will be approximately 23 kHz 6 3 2 Proper Selection of Internal Attenuation 22 When dealing with CW type signals no attenuation is needed to measure field strengths below 0 7 V m At approximately this level the saturation indicator light will come on This indicates a need to switch on the 10 dB attenuator When the 10 dB attenuator is switched on the Model 3301B can measure field strengths up to 2 2 V m without saturating The unit retains 115 dB of dynamic range but the maximum reading before saturation is raised by 10 dB while the minimum discernible signal is
34. nible signal MDS at 1 MHz with a 1 kHz bandwidth is read from the graph at 2 dBuV m The ratio of the bandwidth is 3 123 Taking 10 log 3 we get 4 77 dB Therefore the expected sensitivity would be 2dBuV m 4 77dB 2 77dBuV m Setup and Use Archived 3 18 10 9 0 Theory of Operation 9 1 The Rod There are three factors of primary interest in understanding a rod antenna These factors are its effective electrical length the impedance it presents to the measurement system and the interaction of the rod with the ground The discussion here will contain itself to discussing an electrically short antenna element The Model 3301B is designed to be electrically short over its measurement range Electrically short means an antenna that is designed to have the physical antenna element be short when compared to the wavelength of the highest frequency in its measurement range The current distribution on any rod antenna will be sinusoidal If a rod is short enough with respect to the wavelength being measured that distribution will approach a linear distribution and may be assumed to be linear for all practical purposes The linear current distribution will allow for linear scaling of the rod length If the rod length is reduced by half then the received voltage will be reduced by half The 41 rod is approximately a meter long Electrically then it is a half meter long The assumption of linearity will remain accurate at least to on
35. nsider a specific type of impulse signal the periodic rectangular pulse The pulse may be described by three parameters the pulse width t the pulse repetition rate PRF and the pulse amplitude For a diagram see Periodic Rectangular Pulse Train on page 47 By Fourier analysis we may convert this time domain representation into its frequency domain equivalent In the frequency domain the impulse becomes an infinite series of discrete spectral lines whose envelope is described by the formula YzK sin x X K A t PRF The nulls occur at regular intervals spaced n t apart where n is an integer The discrete spectral lines are spaced evenly at internal multiples of the PRF For an illustration see Spectrum of Rectangular Pulse on page 47 Two characteristics should be noted First increasing the pulse width t narrows the separation of the nulls So wider pulses tend to concentrate their energy in a narrower frequency span Second decreasing the PRF decreases the frequency separation of the individual spectral lines For an illustration see Altering Pulse Width Pulse Repetition Rate on page 48 By considering the frequency domain representation any antenna response to an impulse may be understood The antenna will only pass those spectral components that fall within its bandwidth In the case of the Model 3301B components above 30 MHz will be attenuated or not passed at all Remember to fully describe a rectangular pulse an infin
36. omponent for service Step 1 Contact ETS Lindgren Customer Service to obtain an SRO Service Request Order Step 2 Briefly describe the problem in writing Give details regarding the observed symptom s or error codes and whether the problem is constant or intermittent in nature Please include the date s the service representative you spoke with and the nature of the conversation Include the serial number of the item being returned Step 3 Package the system or component carefully If possible use the original packing materials to return a system or system component to ETS Lindgren at the following address ETS Lindgren Attn Service Department 301 Arrow Point Drive Cedar Park TX USA 78613 Phone 1 512 531 6400 Customer Service 1 512 531 6498 Receiving Your Order 9 Archived 3 18 10 This page intentionally left blank 10 Receiving Your Order Archived 3 18 10 3 0 Maintenance 3 1 Maintenance Recommendations To ensure reliable and repeatable long term performance annual recalibration of your antenna by an ETS Lindgren experienced technician is recommended Our staff can recalibrate almost any type or brand of antenna Please call to receive a Service Order Number prior to sending an antenna for calibration For more information about our calibration services visit our website at http www ETS Lindgren com 3 2 Replacement and Optional Parts Use the following tables to order replacemen
37. quencies all in phase with each other so that measurement of the field strength at any one frequency will not appear to be very Theory of Operation 31 Archived 3 18 10 32 high However the amplifier is being called upon to amplify signals at many frequencies simultaneously In the time domain the amplifier would be seen to be presented with quite a large power demand The result is that impulsive signals appear to saturate the amplifier at must lower signal levels The Model 3301B has been measured to begin going non linear at 64 dBuV m MHz A saturation indicator is provided on the unit This indicator will eliminate many false readings due to non linear operation The saturation indicator has been carefully tested to give an accurate early warning of possible saturation However some types of impulse signals may not trigger the indicator The user must therefore be careful to observe the published limits Should these be exceeded the internal attenuation provided would relieve the problem Theory of Operation Archived 3 18 10 10 0 The Antenna Factor The antenna factor data provided with the unit is simply a ratio of the field strength presented to the unit to the voltage output from the unit at that field strength By adding the antenna factor to a given output the field strength may be derived The antenna factor in the Model 3301B combines several factors The first factor is the 6 dB required to normalize the rod to
38. r specifications which results in whole or in part from 1 negligent storage or handling of the product by Buyer its employees agents or contractors 2 failure of Buyer to prepare the site or provide an operating environmental condition in compliance with any applicable instructions or recommendations of Seller 3 absence of any product component or accessory recommended by Seller but omitted at Buyer s direction 4 any design specification or instruction furnished by Buyer its employees agents or contractors 5 any alteration of the product by persons other than Seller 6 combining Seller s product with any product furnished by others 7 combining incompatible products of Seller 8 interference with the radio frequency fields due to conditions or causes outside the product as furnished by Seller 9 improper or extraordinary use of the product or failure to comply with any applicable instructions or recommendations of Seller or 10 acts of God acts of civil or military authority fires floods strikes or other labor disturbances war riot or any other causes beyond the reasonable control of Seller This warranty does not cover 1 contact fingers or replacements unless loss is caused by a defect in material or manufacturing workmanship within the scope of this warranty 2 items designed to be consumable and 3 removal and reconstruction of walls partitions ceilings and other facility costs arising from repair or replace
39. r the pulse width or pulse repetition rate A narrow pulse width A C spreads the pulse energy over a wider frequency band Wider pulses B D cause narrower lobes A low pulse repetition rate A B creates widely spaced spectral lines Faster rates C D increase the spectral line density 48 Data and Illustrations Archived 3 18 10 ACTIVE ELECTRIC FIELD ANTENNA CALIBRATION FIXTURE SWHO NI SANIYA SWHO 0S T 3ONVISIS3H TIY H3ZXlIVNV JO NI Z EP x 1531 SINHO 0S YAZAIVNV YOLVYANSAD 4O Z WNDIS A 66 09 49 Data and Illustrations Archived 3 18 10 ACTIVE ANTENNA CALIBRATION SETUP VNNALNV JALOV H3ZAVNV HOLO3A HOLVHU3N39 IVNSIS NOILVH8l TVO AINV1d annoud Data and Illustrations 50 Archived 3 18 10 TYPICAL CURVES MiNIMUM DISCERNIBLE SIGNAL AT VARIOUS BANDWIDTHS FREQUENCY MHz SENSITIVITY dBu V m 10 0001 001 Data and lllustrations 100 51 Archived 3 18 10 TYPICAL ATTENUATION EFFECT FOR SWITCHES 1 AND 2 SWITCH ANTENNA FACTOR dB F REQUENCY MHz 40 f 10 52 Data and Illustrations 100 Archived 3 18 10 TYPICAL ROLL OFF CURVES FOR SWITCHES AND 4 SWITCH SWITCH 3 ON 3 OFF 4 OFF 4 ON FREQUENCY MHz ANTENNA FACTOR dB Data and Illustrations 53 Archived 3
40. sitivity This combination of thermal noise and rod impedance sets an ultimate limit on the sensitivity achievable by active rod antennas The sensitivity of the Model 3301B improves with frequency in direct relation to the declining input impedance A common mistake made in regard to sensitivity is to ask what the noise figure of an active rod is Noise figure is defined as The ratio of output noise of a unit over the output noise expected solely due to the thermal noise of the resistance of the input impedance Since the input in the case of a rod is primarily reactive the definition literally has no meaning What is useful is to determine what the minimum discernible signal of a unit is That is what is the smallest signal which can be seen in the presence of the amplifier noise There is a trick here The smallest signal seen above the noise in a rod antenna is not determined by the noise of the amplifier Signal is drained away through capacitive loss before it reaches the amplifier An amplifier with more noise may actually be more sensitive if it also loses less signal to capacitance at the input The upper limit of the Model 3301B is determined by the ability of the gain stage to amplify a signal The gain stages capable of handing field strengths of 0 7 V M are available Impulsive type signals produce the same effect but in such a way as may not be immediately obvious An impulse signal presents the amplifier with signals at a number of fre
41. t or optional parts for the Model 3301B Replacement Part Part Number Collapsible Rod Element 41 101263C 24 x 24 Counterpoise 100692 Rod Antenna Pre Amplifier 100697B Battery Charger 102615 Model 3301B Active Rod amp Field 399046 Antenna User Manual Table 1 Replacement Parts List Optional Part Part Number 3301B Calibration Fixture 3301CB Tripod Linen Phenolic 3 TR Remote Status Monitor 3301B RM 25 Cable RG 223 U with BNC C BNC Connectors Replacement Batteries 6V 2 required 400009 Table 2 Optional Parts List Maintenance 11 Archived 3 18 10 This page intentionally left blank 12 Maintenance Archived 3 18 10 4 0 Standard Configuration e Adjustable monopole element Antenna base with built in preamplifier and an isolated female BNC connector Counterpoise 60 cm Base drilled to accept EMCO or other tripod mounts with standard 4 x 20 threads e Batteries and battery charger e Individually calibrated ECSM or IEE Std 291 Actual individual calibration factors and signed Certificate of Calibration Conformance included with the manual 4 1 Options REMOTE MONITOR A 10 meter 32 8 ft fiber optic Remote Monitor Option for remote display of power on and saturation indicators TRIPODS ETS Lindgren offers two nonmetallic non reflective tripods for use at both indoor and outdoor EMC test sites e Mo
42. tached to a counterpoise through the top grounding strips In screen room testing the counterpoise should be solidly attached to the screen room wall as required for military testing If the unit is to be mounted on a tripod it is recommended that the tripod be non conductive Setup and Use 27 Archived 3 18 10 8 2 High Sensitivity Readings 28 The Model 3301B is optimized to facilitate extremely sensitive readings For best performance all internal attenuation should be off The gain switch should be placed in the low gain setting The noise limiting factor on the Model 3301B is the high front end impedance presented to the FET So when the gain stage output is increased with the gain switch the noise is also amplified and actually increased slightly due to additional noise added in the gain state The high gain setting is primarily intended to provide additional signal strength for receivers that require it A set of minimum discernible signal graphs is included in this manual These graphs represent the smallest signal which can be detected with the Model 3301B The data plotted are the noise output of the unit As a result this forms the noise measurement for a signal plus noise to noise ratio of 3 dB Several typical bandwidths are presented To calculate the expected sensitivity at some other bandwidth a 10 log relation should be used EXAMPLE Determine the sensitivity with a 3 kHz bandwidth at 1 MHz The minimum discer
43. ttled in Austin Texas by arbitration in accordance with the Rules of the American Arbitration Association and judgment upon the award rendered by the Arbitrator may be entered in either the Federal District Court for the Western District of Texas or the State District Court in Austin Texas all of the parties hereto consenting to personal jurisdiction of the venue of such court and hereby waive the right to demand a jury trial under any of these actions Warranty Policy for Standard EMCO Brand Products 43 Archived 3 18 10 This page intentionally left blank 44 Warranty Policy for Standard EMCO Brand Products Archived 3 18 10 Appendix B European Community Declaration of Conformity The EC Declaration of Conformity is the method by which EMC Test Systems L P declares that the equipment listed on this document complies with the EMC and Low voltage Directives Factory Issued by EMC Test Systems L P EMC Test Systems L P P O Box 80589 P O Box 80589 Austin Texas USA 78708 0589 Austin Texas USA 78708 0589 The products manufactured under the EMCO product name and listed below are eligible to bear the EC Mark Model 3301B Active Rod Antenna Part number 102615 Battery Charger APPLICABLE REQUIREMENTS Standard Criteria EN61010 1 Safety requirements for electrical equipment for measurement control and laboratory use EN60742 1989 Isolating transformers and safety isolating transformers EN55022 Class B
44. uration Impedance A red LED on the front panel will illuminate when the unit begins to saturate or clip The saturation indicator will indicate accurately for any gain and attenuator setting Battery Low Indicator The power light on the front panel also serves as a battery low Indicator If the green light does not come on when the power switch is engaged then the battery requires recharging It is recommended that the Model 3301B be connected to the battery charger at all times when not in use 16 Specifications Archived 3 18 10 Batteries The Model 3301B is supplied with two 6V sealed lead acid batteries The batteries will operate for approximately 10 hours between charges Battery Charger 115 230 VAC 50 60 Hz switch selectable IEC input two stage battery charger with fast and trickle charge modes Fuses e Type 3AG size 5 Amp fast acting Or 5x 20 mm 5 Amp fast acting e Internally mounted 5 3 Mechanical Specifications Size 7 38 x 4 62 x 3 5 Weight Approximately 7 lbs Tripod Mounting A x 20 hole is provided on the base for tripod mounting This is not intended as a grounding point Counterpoise Mounting Four 6 32 holes are provided in the two metal mounting bars on the top of the unit Antenna Element The antenna element may be set up to 41 Specifications 17 Archived 3 18 10 T
45. ype signals However for fast transients the capacitor like all capacitors has an integrating effect The DC level established by a fast transient is spread out in time After the pulse passes the capacitor Antenna Impulse Response Archived 3 18 10 begins to discharge through its resistance to ground If the PRF is slow enough so that the capacitor is fully discharged before the next pulse arrives it may never trigger the indicator The antenna amplifier on the other hand must satisfy the instantaneous energy demand It must respond to the peak demand without any integrating effect If the product of the pulse width and PRF is less than 0 003 the saturation indicator will fail to indicate properly The time constant of the saturation indicating capacitor also sets the persistence of the saturation circuit To have the saturation circuit cease to indicate saturation within a reasonable time after the antenna moves out of saturation a reasonable RC time constant must be maintained This choice of RC time constant also creates this limit for impulsive signals In this region the user must closely monitor the antenna output for saturation 11 3 Pulse Charging The second criterion that must be met is that the PRF must fall below the rate listed in Impulse Characteristics on page 35 for the appropriate duty cycle This requirement is created by the AC coupling in the Model 3301B circuitry To allow maximum dynamic range through the Model
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