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Receive Eight Circle Array

Complete System Package

DXE-RCA8C-SYS-4P

U.S. Patent No. 7,423,588

DXE-RCA8C-SYS-4P-INS Revision 0b

1200 Southeast Ave. - Tallmadge, OH 44278 USA

Phone: (800) 777-0703 ∙ Tech Support and International: (330) 572-3200

Fax: (330) 572-3279 ∙ E-mail: [email protected]

Summary of Contents for DXE-RCA8C-SYS-4P

Page 1: ...XE RCA8C SYS 4P U S Patent No 7 423 588 DXE RCA8C SYS 4P INS Revision 0b DX Engineering 2018 1200 Southeast Ave Tallmadge OH 44278 USA Phone 800 777 0703 Tech Support and International 330 572 3200 Fax 330 572 3279 E mail DXEngineering DXEngineering com ...

Page 2: ...e 10 Vertical Element Feedlines 11 Typical DXE RCA8C SYS 4P Receive Eight Circle Configuration 12 Delay Line 13 Optimizing the Array 13 Theory of Operation of the Receive Eight Circle Array 14 System Design Features and Benefits 14 Frequency Coverage vs Element Type 15 Receive Antennas Gain and Efficiency 16 Site Selection 16 Effects on Patterns 17 Site Selection in Relation to Noise Sources 17 Pr...

Page 3: ...etter signal to noise ratio Reduced susceptibility to high angle signals compared to phased Beverage antennas as well as superior performance over EWE Flag Pennant K9AY antennas Switching console selects one of eight 45 spaced directions Directivity over a very wide frequency range Less physical space and less maintenance required than phased Beverage antenna arrays Enhanced relay contact reliabil...

Page 4: ...mpression Tool for 75Ω coaxial cable connectors DXE SNS6 25 Package of 25 Snap N Seal Connectors for 75Ω F6 coaxial cable Additional Parts Required Not Supplied with the DXE RCA8C SYS 4P One additional DXE 6UF 1000 75Ω Coaxial Cable that may be required for the main feedline from the station to the array Five Conductor Power and Control Cable The modified DXE CC 8A Control Console interfaces to th...

Page 5: ...ntroller eight DXE AVA2 Active Matching Units for your vertical elements and one Delay Cable with F Connectors installed These units interconnect and work together using factory default settings to control the Receive Eight Circle Array The modified CC 8A control console uses BCD switching voltages for the RCA8C 1 to change the receiving direction of the array When the modified CC 8A Eight Circle ...

Page 6: ...Controller unit should be mounted as shown in Figure 3 with cover upward and the control and coaxial cable connections downward to prevent water from entering the box The stainless steel base of the Receive Eight Circle Array Controller unit has weep holes to allow condensation that may build up inside the unit to leave Figure 3 RCA8C 1 unit mounted to 2 pipe using the included DXE SSVC 2P V Clamp...

Page 7: ... connections are labeled G A B C D The terminals use the same connection letters and are connected G to G A to A B to B C to C and D to D On the RCA8C 1 the green connector is a two part connector as shown in Figure 5 and the top part can be removed by pulling it straight off This will allow easier wire replacement or servicing as needed When pushing the removable connector back in place ensure yo...

Page 8: ...rol Line Lengths Minimum Copper Wire Gage AWG Length 24 1 000 feet 22 1 500 feet 20 2 000 feet Active antenna circuitry needs a good voltage supply to operate properly When supplying power to an active antenna you want to have 12 VDC 60 milliamps at each active under load CAT5e cable is not recommended when making long runs to power an active antenna since the line loss in CAT5e cable may not supp...

Page 9: ...smitting antennas 1 10 wavelength of the lowest transmitting frequency This is possible provided the active units are powered off at least 5 ms before transmitting An optional sequencer such as the DXE TVSU should be used to ensure the correct transmit to receive switching Your eight identical DXE ARAV4 1 Active Vertical Antennas must be mounted so they are self supporting and insulated from the m...

Page 10: ...s than 5 8 OD A good ground system improves the array performance and enhances lightning survivability It is important that the ground system is identical for each active antenna in the array You can test ground quality by listening to a steady local signal Attach 15 ft of wire laid in a straight line away from the coaxial feedline to the initial 4 ft to 6 ft ground rod If you observe a change in ...

Page 11: ...e 75Ω feedline to the operating position from the DXE RCA8C 1 unit Do not use amplifiers combiners filters or splitters that are not optimized for 75Ω systems All element feedlines must be 75Ω and can be any length as long as they are all equal and they should come from the same roll of cable so they have the same velocity factor VF The weakest link in an antenna system is often the coaxial cable ...

Page 12: ...n the chassis mounting nut allowing the connector body to rotate and fracture the mounting tabs on either installation or removal of the connector F connectors require modest torque typically 6 12 inch pounds 20 30 inch pounds are FAR too high That value although commonly used is just wrong Damage to the various connectors may result and is not covered under warranty Use a tool such as the DXE CIT...

Page 13: ...n Figure 8 Coaxial Cables are shown in various colors for clarity Shown with optional DXE RPA Receive Pre Amplifier DXE RFCC Receive Feedline Current Choke and optional DXE CW9S Control Cable Power connection to the modified DXE CC 8A Control Console is not shown ...

Page 14: ...nna and set the receiver to the narrowest selectivity you expect to use Receiver noise power is directly proportional to receiver bandwidth going from 2 5 kHz selectivity to 250 Hz selectivity reduces noise by 10 dB Connecting the antenna should result in a noticeable increase in noise If so the array signal level is sufficient and further optimization or amplification may not be needed If the arr...

Page 15: ...ms a clean stable pattern with high directivity over wide bandwidth W8JI initially developed and used this array in the 1980 s This array started appearing in the 1990 s at larger more advanced low band DX stations The phasing system in this array as well as the active element design offer much better dynamic range and directivity bandwidth than other later copies Unlike unidirectional transmittin...

Page 16: ... broadband active elements this array has unbeatable performance across a single band The Eight Circle Array upper frequency limit for a clean unidirectional pattern is slightly above where the array is 35 wavelength radius The frequency of optimum performance is where the array is approximately 327 wavelength radius Construction care element construction desired beamwidth and local noise floor de...

Page 17: ...primary benefit Antenna gain is a secondary advantage As frequency increases the fixed array size becomes electrically larger in terms of wavelength The increased electrical spacing produces higher sensitivity average gain even though front to rear ratio only changes slightly On the low bands once the receiving system including the antenna system and the receiver are hearing the lowest possible le...

Page 18: ...ductors regardless of element design for a given style of element The effect on pattern depends almost entirely on how much surrounding objects absorb and re radiate signals if the undesired structure is in a null or peak of the receiving array and how close the systems are in terms of wavelength With so many variables involved there is no optimum or minimum spacing for effects on pattern The best...

Page 19: ...imity to Transmitting Antennas The AVA2 Active Matching Units with customer supplied vertical elements or the DXE ARAV4 8P Receive Antenna Active Vertical with Relay active elements and your transmitting antenna need only minimal physical separation to maintain safe power levels when the DXE TVSU Time Variable Sequencer Unit is used With 1500 watts output and a unity gain 0 dB antenna the closest ...

Page 20: ... of 327 wavelength This pattern achieves the best Receiving Directivity Factor RDF which is a figure that compares the forward lobe gain to the average gain of the antenna array in all directions including azimuth and elevation More information about the rating of receive antenna systems and Receive Directivity Factor are described in ON4UN s Low Band DXing by John Devoldere available from DX Engi...

Page 21: ...allowable side lobe levels as represented closely to the pattern 35 wavelength radius shown in Figure 9 For example an array built to cover 160 80 and 40 meters has a highest frequency of 7 3 MHz and a 375 wavelength radius of about 50 5 feet which offers excellent rear rejection on 40 meters a respectable cardioid pattern on 80 meters and still offer useable directivity on 160 meters The patterns...

Page 22: ...patterns in Figure 10 were generated using EZNEC and show the effects on the patterns when varying the radius of the array These patterns are not to be viewed as pointing in a default or particular direction Figure 10 ...

Page 23: ...u are using you must directly measure the electrical length of the coaxial cable you have with an analyzer or obtain cable with a known VF Table 3 shows delay line length calculations based on the dimensions for the three most common Receive Eight Circle Arrays Note These calculations are in decimal feet not feet and inches Band Coverage Desired Optimal Eight Circle Array 327 wavelength Radius in ...

Page 24: ...dimensions rather than operating frequency which allows for the use of a single delay line for optimum directivity over a very wide frequency range This results in phase being correct for a rearward null at any frequency The delay line cable can be neatly coiled in a 1 1 2 ft diameter coil Support the weight of the coiled cable by taping or securing it to the support pole or mast rather than allow...

Page 25: ...cle Array is sized by multiplying the free space wavelength at 1 832 MHz of 537 feet wavelength times the optimum pattern circle radius of 0 327 wavelength which yields an optimal circle radius of 175 6 feet This places the vertical elements about one quarter wavelength apart 134 25 feet However as shown by the patterns of Figure 10 an optimized 160 meter Eight Circle Array is not useable on 80 me...

Page 26: ...32 26 66 13 172 8 345 6 319 3 0 604 3 500 70 29 35 14 91 8 183 7 169 7 0 604 3 650 67 40 33 70 88 1 176 1 162 7 0 604 3 800 80M only or 160 80M 64 74 32 37 84 58 169 2 156 3 0 604 7 200 40M only 34 17 17 09 44 66 89 32 82 5 0 604 160 80 40M special array 6 369 MHz 38 6 19 3 50 5 101 0 93 28 0 604 Table 5 Array Dimensional Layout Highlighted figures are optimal for 1 83 3 8 and 7 3 MHz Special Arra...

Page 27: ...ve pulled inward C Shorted Open conductors due to water Check feedlines and control cable D Zapped by lightning pulse or RF overload Make sure units are at least 1 2 wavelength on the lowest frequency away from any transmit antenna May want to use an optional DXE TVSU Time Variable Sequencer for AVA2 units E Damaged due to lightning Rare but it can happen F Damaged by animals or insects Animals ha...

Page 28: ... Active antennas and any transmit antennas If that distance is less and high power is used then the Time Variable Sequence Unit TVSU must be used to interrupt power to the AVA2 units 2 Damaged Receive Eight Circle unit due to lightning This has been reported only a couple of times and is not very likely 3 Active units that were damaged by animals Once we received actives damaged by an animal that ...

Page 29: ...is disconnected from the Receive Eight Circle System relay unit If measured voltages are not between 10 to 18 Vdc on the selected line a resistive short or open circuit problem exists in the control line or in the Receive Eight Circle System relay unit or antenna feedlines Normal voltages on the connected control line will cause relays to switch inside the Receive Eight Circle System unit If switc...

Page 30: ... of that antenna may not be receiving power Retest for DC power at the antenna end of that feedline If 10 to 18 Vdc is found then the Active unit may need to be serviced or replaced New AVA2 units are available separately by calling DX Engineering 10 If all Active Verticals tested provide the same signal level then change switching voltages to activate the other ports one at a time and test each R...

Page 31: ... 31 NOTES ...

Page 32: ...tallation damaged from severe weather including floods or abnormal environmental conditions such as prolonged exposure to corrosives or power surges or by the performance of repairs or alterations outside of our plant and shall not apply to any goods or parts thereof furnished by Buyer or acquired from others at Buyer s specifications In addition DX Engineering s warranties do not extend to other ...

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