Generic RFI Handbook
Contents
1. 146 ANVeINGO SAVMOHOIN GL WHO 3435 SETANINA ONITASNOD 53402 315453 40 SNIMCHS NOSMVd 0409 YIMOd 30 59 53405 314933 ERACE AAE S 5 WILNA TWAS NO dNd 3803 SLR 7 7 1 399 W3LSAS 3189 9 VNN3INY 318 2 9805 30 0 3 YOLINOW OL 3195504 SV 35013 SV 538053 318433 01108401 TIVLSNI 17914 335 31113 9 706 4 5 YO 55 4 ANVdNOD XILI SAVMOYSIN 5 3 WHO SZ 2 3731 YOLINOW AN3 YALNdNOD OL 31815504 SY 35019 Sv 35053 315434 210401 11 16 1 02. WHO SZ WHO 008 STWNIWNAL 3 5 318 0 ONISN 318 2 390 SHLONT 5633 3 1102 AILHSIL 16661 11690 3809 ALM 5 29042048P 03315 31691804 NO 00801 3309 313433 5 9805 30 3 3ONVNddv 21815509 SV 35012 SV 3409 34 TIVISNI 310 9395 NO 3803 314433 0 8 1 1011102255 034316 AIGVLYOd NOSMVG 014 1 45 e1qeyoojep 0265 1350 3X09 39833 0505 JNOHd OL 0300 38 OL OJAN Yas 09 35 0805 1109 ZHN DOL 0235 Wald 139 0109 9805 100 gt ZHN 001 ms WOO 583118 JNOHAS TAL ONIETASNOD SNIMCHS 0141 9305 40 01 31815504 SY ASAT SY 53400 3195433 TW TIVLSNI ILON 3805 51433 DIONOL LOLL 104465 11 75 441 1339103 2 001 143 95 5 INSNCdWOD 038315 NO 5531113 ONILIASNOD 5 0503 40 OL 5311 3182
3. filter between the transformer and the TV S 75 Ohm input connector Plug the AC cord back into the wall outlet Turn on the TV and check to see if these steps have solved the interference problems Check solid single color areas of the picture for signs of herringbone interference vertical zigzag lines If the interference is still present or if you need additional assistance call the radio station s Interference Assistance line at H H leave a message and the radio station representative will return your call Filters and ferrite cores can be obtained by calling the same number Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 4 of 20 Installation of a Notch Filter and Ferrite Toroid Core on a TV Receiver with Screw Terminals at its Antenna Input See Figure 2 1 Unplug the TV s AC power cord from the wall outlet 2 Thread the AC power cord through the center of the toroid corn and slide the core up the cord to within 1 or 2 inches of the TV set Wrap the power cord around the outside of the core through the center of the core and around the outside of the ferrite corn again as many times as possible with most power cords it is possible to wrap 10 or 11 turns through the toroid core Wrap the cord at tightly as possible around the core See Figure 1 for an illustration of how to wind the power cord through the core 3 For TV s connected to rabbit ears or to a 300 Ohm
4. s Interference Assistance line at H leave a message and a the radio station representative will return your call Filters and ferrite cores can be obtained by calling the same number Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 7 of 20 Installation of a Notch Filter and Ferrite Toroid Core on an FM Receiver with Screw Terminals at its External Antenna Input See Figure 2 The drawing at the top of Figure 2 shows the installation of a filter on a TV set The installation of a filter on the external antenna input of a FM receiver follows the identical process only the box to which the filter or leads are connected is a FM receiver rather than a TV set l 2 Unplug the FM receiver s power cord from the wall outlet Thread the AC power cord through the center of the toroid core and slide the core up the cord to within 1 or 2 inches of the FM tuner or receiver Wrap the power cord around the outside of the core through the center of the core and around the outside of the ferrite core again as many times as possible with most power cards it is possible to wrap 10 or 11 turns through the toroid core Wrap the cord as tightly as possible around the core See Figure 1 for an illustration of how to wind the power cord through the core For FM tuners and receivers connected to rabbit ear or to a 300 Ohm twinlead flat cable rooftop antenna downlead a
5. twinlead flat cable rooftop antenna downlead a If the TV is connected directly to a section of 300 Ohm twinlead flat cable with two wires at the end from the rooftop antenna or from a pair of rabbit ears disconnect the 300 Ohm cable from the screw terminals at the rear of the TV b Attach the screw terminals on a 300 to 75 Ohm transformer Radio Shack 15 1252 or equivalent to the end of the 300 Ohm cable and attach the type F plug on the transformer to one end of the Microwave Filter Company 5 or 5 notch filter the plug attaches to the end of the filter with the screw threads on the outside of the filter s connector see Figure 2 c If your TV has a single set of screw terminals at its antenna input connect the other end of the filter to a 75 Ohm to 300 Ohm transformer Radio Shack 15 1140 or equivalent Attach the leads from the transformer to the screw terminals on the TV as shown in Figure 2 it doesn t matter which lead goes to which screw d If your TV has two separate sets of screw terminals labeled VHF and connect the other end of the filter to 75 Ohm to 300 Ohm VHF UHF splitter combiner Radio Shack 5 1252 or equivalent Attach the leads from the splitter combiner to the appropriate screw terminals on the TV as shown in Figure 2 both the splitter combiner and the TV will be labeled and Hatfield amp Dawson Cons
6. 14 of 20 How to Install a Powered Splitter to Increase TV Signal Levels In Your Household Cable Distribution System See Figure 6 In many cases blanketing interference from the radio station to newer television receivers connected to the cable system results from inadequate TV signal levels at individual TV sets Often a 2 way or a 4 way splitter will be installed at the main cable feed point to allow connection of several TV sets Sometimes an additional 2 way splitter will be installed downstream from the 4 way splitter to add further branches to the household cable system These splitters reduce the signal level at each TV significantly from the level that would have been available from the cable system had only a single TV been connected at the main cable feed The reduced signal strength at the TV receivers makes them more susceptible to interference from the strong the radio station Our tests have shown that most newer TV sets do not show symptoms of blanketing interference if they are fed a standard main cable feed point input level of 0 dBmV and if the level of the radio station signal inside the cable system is not more than 10 dB higher than the level of the TV signals in the cable Often the installation of an amplifier to boost the signal levels at all the TV sets in the house will eliminate interference from the radio station The simplest way to install such an amplifier or amplifiers is to replace the passive 2 way
7. If the tuner or receiver is connected directly to a section of 300 Ohm twinlead flat cable with two wires at the end from the rooftop antenna or from pair of rabbit ears disconnect the 300 Ohm cable from the screw terminals at the rear of the tuner or receiver Attach the screw terminals on a 300 Ohm to 75 Ohm transformer Radio Shack 15 1252 or equivalent to the end of the 300 Ohm cable and attach the type plug on the transformer to one end of the Microwave Filter Company 5KV XX X 5 notch filter the F plug attaches to the end of the filter with the screw threads on the outside of the filter s connector see Figure 2 If the tuner or receiver has a set of screw terminals labeled 300 Ohms or simply external antenna at its antenna input connect the other end of the filter to 75 Ohm to 300 Ohm transformer Radio Shack 15 1140 or equivalent Attach the leads from the transformer to the screw terminals on the tuner or receiver as shown in Figure 2 it doesn t matter which lead goes to which screw Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 8 of 20 d Make sure that the connections to the fitter are tight use your fingers don t tighten them with a wrench or you may damage the threads on the connectors 4 For tuners and receivers connected to 75 Ohm coaxial cable lead in from a rooftop antenna or from the cable system a Co
8. and 4 way splitters in the cable distribution system with powered splitters which are simply amplifiers and splitters combined in a single box with an AC cord attached To replace a passive splitter with a powered splitter 1 Disconnect the cables from the passive splitter making sure you know which cable is the input cable and which cables are the output cables 2 Connect the input cable and the output cables to the powered splitter Radio Shack Four Set Amplified Coupler 15 1119 or equivalent replaces 4 way splitter Radio Shack Two Set Amplified Coupler 1 51 116 or equivalent replaces a 2 way splitter It does not matter which outputs you use to connect the output branch cables but it is a good idea to label the cables so that you know later where each one goes Also any unused outputs must be terminated with a 75 Ohm terminating resistor Radio Shack 15 1144 or equivalent 3 Install a clip on ferrite core on the powered splitter s AC power lead as follows Thread the AC power cord through the center of the toroid core and slide the core up the cord to within 1 or 2 inches of the powered splitter case Wrap the power cord around the outside of the core through the center of the core and around the outside of the ferrite core again as many times as possible with most power cords it is possible to wrap 10 or 11 turns through the toroid core Wrap the cord at Hatfield amp Dawson Consulting Engineers t
9. center of the toroid core and slide the core up the cord to within 1 or 2 inches of the computer or monitor Wrap the power cord around the outside of the core through the center of the core and around the outside of the ferrite core again as many times as possible with most power cords it is possible to wrap 10 or 11 turns through the toroid core Wrap the cord at tightly as possible around the core See Figure 7 for an illustration of how to wind the power cord through the core Disconnect the 75 Ohm connector on the antenna or cable system lead in from the antenna input at the rear of the TV or FM tuner card Connect the Microwave Filter Company 5KV XX X 5 notch filter directly to the antenna input at the rear of the TV or FM tuner card Connect the antenna or cable system lead in to the opposite end of the filter from the TV or FM tuner card Make sure that the connections are tight use your fingers don t tighten them with a wrench or you may damage the threads on the connectors If you have an external antenna with 300 Ohm twinlead flat cable as the antenna lead in then there is already a 300 Ohm 75 Ohm transformer installed between the 300 Ohm cable and the 75 Ohm connector on FM tuner card Install the filter between the transformer and the TV S 75 Ohm input connector Attach a clip on ferrite core on each of the leads connecting the output of any external unit tape player C
10. for the instillation of clip on ferrite cores on page 10 Wrap a few windings of the handset cord around the clip on core and then close the two halves of the core s box If your phone has an integral answering machine install a clip on ferrite core on the DC power lead as close to the connection to the phone as possible this is the lead which is connected to the transformer which plugs into the wall You may find the same step is necessary for a cordless phone If none of these measures eliminate the interference to the telephone you may have to replace your phone Please contact the radio station for suggestion of a phone model that works in high RF fields If the interference is still present or if you need additional assistance call the radio station s Interference Assistance line at HH HHH H leave a message and the radio station representative will return your call Filters and ferrite cores can be obtained by calling the same number Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 12 of 20 Installation of Clip on and Toroid Ferrite Cores on a Typical Portable AM FM Cassette Boom box See Figure 5 1 If possible disconnect the AC power cord from the mar of the boom box Install a toroid ferrite core on the AC cord as follows Thread the AC power cord through the center of the toroid core and slide the core up the cord to within 1 or 2 inches of the boom box end of the power co
11. phone jacks as antenna connectors rather than type F coaxial connectors These connectors are not RF tight and these TV s tend to show severe interference symptoms in the presence of the high levels of RF fields typical in the vicinity of an FM broadcast station TV receivers with this kind of antenna connector should be avoided in the the radio station blanketing area Small portable TV receivers equipped with type connectors which connect directly to the tuner s shielded enclosure appear to operate as well as their larger counterparts given sufficient TV signal strength to produce a quality picture Examples of these smaller RV receivers include Panasonic CT 10R11 10 Color Tv Sony KV 9PT40 9 Color TV AM FM Cassette CD Boomboxes The following AM FM Cassette or AM FM Cassette CD Boomboxes have been found to operate flawlessly in the vicinity of the the radio station transmitter when provided with a clip on ferrite core on their AC lead and in some cases when operated with their whip antennas in the storage position rather than fully extended JVC PC X105 AM FM Dual Cassette CD digital tuner Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 20 of 20 JVC RC QS11 AM FM Cassette CD digital tuner Soundesign 4743BLK AM FM Cassette analog tuner AM FM Cassette CD Phono Micro Component Stereo Systems The following micro component stereo systems have been found to operate fl
12. 215 4 3185504 SV 35010 318 2 INILOINNOD 440 53805 318533 19 37 SS39X3 7102 ATHOLL 00401 2310 JTAVINENL 22 35979 SINU 6 2 143 313 31553 0902 COT 3409 Suu 1 T A ETa Erg Bw 3X09 314543 910501 15371 1911104466 5 YIAGOIY YANIdNY 014115 AIQWASSY INSNONOD 038315 53113 0801 SANNA ONIETASNOD 53802 313834 03 519130 NOLLVTIVISNI SNIMOHS ve NOSMVG THMLVH SS 22277 25525252251 7273 lt 7 lt lt lt RRR gt gt gt 5555521 52255225254 5 5311 318 2 ALSWd FVD INILOINNOD 440 19 37 SS39X3 193 ATHOLL ISD 53 6 2 IN3WJI3 31553 0902 wow ov QUAN 1011104465 SLY ORS 1397 IHON 1397 1331 N 83345 XAV YIAGOIY YAMIN 15 AIQWASSY INSNONOD 038315 53113 0801 SANNA ONIETASNOD 53802 313834 03 519130 NOLLVTIVISNI SNIMOHS ve NOSMVG THMLVH SS 22277 25525252251 7273 lt 7 lt lt l
13. D player equalizer etc to the input of the computer sound card as shown in Figure 7A Install the clip on ferrite core as close to the input to the sound card as possible within 1 or 2 inches if possible Most component stereo systems come with dual connecting cables with the right and left channels leads separated only at the ends of the cables where the connectors are installed Install the cores as follows a Wind 2 or 3 windings around one side of the open clip on ferrite core as shown in Figure 3A or Figure 3B using the slot running through the center of one side of the cone as a trough to hold the cables b Close the other half of the core over the cable windings and press the two halves of the core together until the locking clips on the side of core box snaps closed Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 17 of 20 After the cores are installed the cables coil the excess lengths of the connecting cables as shown in Figure 3A or Figure 3B and use a plastic cable tie available at Radio Shack and at many hardware stores to hold the coiled cable together d Plug each end of the cables into the appropriate connectors on the amplifier and on the component being connected to the amplifier 5 Install clip on ferrite cores on the left and right speaker leads and on all of the speaker leads if you have surround sound or some other multi speaker system Use the
14. JAMES B HATFIELD PE BENJAMIN F DAWSON III PE THOMAS M ECKELS PE STEPHEN S LOCKWOOD PE DAvID J PINION PE PAUL W LEONARD PE ERIK SWANSON EIT THOMAS S GORTON PE HATFIELD amp DAWSON CONSULTING ELECTRICAL ENGINEERS TELEPHONE 9500 GREENWOOD AVE N 206 783 9151 SEATTLE WASHINGTON 98103 FACSIMILE 206 789 9834 E MAIL lockwood hatdaw com Maury L HATFIELD PE CONSULTANT Box 1326 ALICE SPRINGS NT 5950 AUSTRALIA HANDBOOK ELIMINATING RADIO FREQUENCY BLANKETING INTERFERENCE FROM ELECTRONIC EQUIPMENT A BRIEF TUTORIAL UPDATED JANUARY 2003 the radio station XX X MHz City State Page 1 of 20 Introduction This manual contains a description of the techniques and materials for eliminating the effects of blanketing interference from FM radio stations Many residents living in the vicinity of the transmitters have experienced problems with interference to their telephones FM radios television sets boomboxes and stereo equipment caused by the strong signal produced by the FM radio station in the immediate vicinity of its transmitter site Blanketing interference to TV and radio receivers occurs when an FM broadcast station s signal strength at the affected receiver is sufficiently strong to overload the receiver and to partially or completely block it from receiving other broadcast signals Blanketing interference is a function of receiver design characteristics some receivers are affect
15. awlessly in the vicinity of the the radio station transmitter when provided with a clip on ferrite core on their AC leads and on their speaker leads and when provided with a Microwave Filter Company 5 notch filter between their external antenna terminals and the 300 ohm twinlead folded dipole wire antenna provided with each unit These units are fully sheilded by a metal enclosure have very high quality digital FM tuners and have external antenna connections to allow them to be connected to the cable system or to a rooftop antenna The Samsung unit comes with a phono preamplifier so that the combination of it and a turntable can be used to replace an older system with an integral turntable JVC Sony MHC 450 Samsung SCM 8300 AM FM CD with RIAA phono inputs Shortwave Receivers The Grundig YB 400 Yacht Boy portable AM FM shortwave receiver operates flawlessly throughout the the radio station blanketing area This is a small handheld portable radio which can also be made to operate with AC power using a 9 Volt adaptor A clip on ferrite must be installed at the radio end of the DC power lead if to allow the unit to operate with AC power in the presence of the strong the radio station RF field The receiver must also be operated in the local rather than the distant mode to allow for proper operation in the the radio station blanketing area Telephones There are many AT amp T ATT5300 cordless phones opera
16. ceiver follows the identical process only the box to which the filter or leads are connected is an FM receiver rather than a TV set 1 2 Unplug the FM receiver s AC power cord from the wall outlet Thread the AC power cord through the center of the toroid core and slide the core up the cord to within 1 or 2 inches of the receiver Wrap the power cord around the outside of the core through the center of the core and around the outside of the ferrite core again as many times as possible with most power cords it is possible to wrap 10 or 11 turns through the toroid core Wrap the cord as tightly as possible around the core See Figure 1 for an illustration of how to wind the power cord through the core Disconnect the 75 Ohm F connector on the antenna or cable system lead in from the antenna input at the rear of the receiver Connect the Microwave Filter Company 5KV XX X or 5KFM XX X notch filter directly to the antenna input at the rear of the receiver Connect the antenna or cable system lead in to the opposite end of the filter from the receiver Make sure that the connections are tight use your fingers don t tighten them with a wrench or you may damage the threads on the connectors Plug the AC cord back into the wall outlet Turn on the receiver and check to see if these steps have solved the interference problems If the interference is still present or if you need additional assistance call the radio station
17. cord through the core 3 Attach a clip on ferrite core on each of the leads connecting the output of one unit tape player CD player equalizer etc to the input of the amplifier or pre amplifier usually the unit with the volume control and switches for choosing different inputs Install the clip on ferrite core as close to the input to the amplifier or pre amplifier as possible within 1 or 2 inches if possible Most component stereo systems come with dual connecting cables with the right and left channels leads separated only at the ends of the cables where the connectors are installed Install the cores as follows a Wind 2 or 3 windings around one side of the open clip on ferrite core as shown in Figure 3A or Figure 3B using the slot running through the center of one side of the cone as a trough to hold the cables b Close the other half of the core over the cable windings and press the two halves of the core together until the locking clips on the side of core box snaps closed After the cores are installed on the cables coil the excess lengths of the connecting cables as shown in Figure 3A or Figure 3B and use a plastic cable tie available at Radio Shack and at many hardware stores to hold the coiled cable together d Plug each end of the cables into the appropriate connectors on the amplifier and on the component being connected to the amplifier Hatfield amp Dawson Consulting Engineers the radio statio
18. ed more than others in the presence of a strong signal from an FM broadcast station Also the effects of blanketing interference are more severe when the TV or FM receiver is tuned to a weaker desired signal rather than to a stronger one FM broadcast stations must radiate relatively high levels of power from their transmitting antennas in order to provide coverage to their areas of service Therefore the available solutions for blanketing interference problems all involve either increasing the level of the desired signal the signal from the TV station you are trying to watch or the FM broadcast station you are trying to listen to and or decreasing the level of the interfering signal the signal from the radio station at the antenna input to the TV or FM receiver In the case of other electronic equipment such as telephones and cassette players for example preventing interference involves preventing the radio frequency energy from the radio station from entering the circuitry of the equipment The techniques for eliminating blanketing interference described in this tutorial have been used successfully by various radio station personnel to solve a significant number of interference problems in households throughout the immediate vicinity of its transmitter site some have been as close as 75 feet to the transmitting facility The filters shown in the diagrams in the following pages are used to notch out the radio station signal at the input to a TV
19. een the phone line and the line connector on the telephone Install the filter at the telephone end of the line between the wall and the phone The filter has standard modular phone connectors Simply unplug the line plug in the filter in its place and plug the line into the other end of the filter Install a Coilcraft TRF RJ or K Com RF1 VHF filter at the phone end of the handset cord on a standard telephone The filter has standard modular phone connectors that mate with the headset plug and telephone jack Simply unplug the line plug in the filter in its place and plug the line into the other end of the filter The connectors on the handset cord are a different size than those at the line connector on the phone so if you find that the connector does not fit in either case check to see which filter you are attempting to connect to which connector even those of us who have installed a large number of these filters run into this problem Try extending the handset cord to its full length walk around the room listening to the phone s receiver press 9 or 1 first to eliminate the dial tone Listen for the radio station audio If there is still audible interference try installing another filter at the handset end of the handset cord as shown in Figure 4 and then listen again for interference If interference is still audible then install a clip on ferrite core on the phone end of the handset cord as shown in Figure 4 See the instructions
20. he radio station XX X MHz City State Page 15 of 20 tightly as possible around the core See Figure 1 for an illustration of how to wind the power cord through the core 4 Check to make sure that all the connectors in your system at the main feed point at splitters at switchers at cable converters and at TV sets are screwed on as tightly as you can screw them with your fingers DO NOT USE PRESS ON CABLE CONNECTORS OR ADAPTERS These provide much less RF shielding than the screw on types 4 Plug the AC power cord into a wall outlet near the powered splitter 5 Check each TV to see if there is an improvement in the picture quality and to determine if you have eliminated the interference if there was any to begin with 6 If the interference is still present or if you need additional assistance call the radio station s Interference Assistance line at leave a message and the radio station representative will return your call Filters and ferrite cores they can be obtained by calling the same number Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 16 of 20 Installation of a Notch Filter and Ferrite Toroid Cores on a Computer TV or FM Tuner card with 75 Ohm Connector Antenna Input or a computer sound See Figures 7 and 7A 1 2 Unplug the Computer and Monitor power cords from the wall outlet Thread each AC power cord through the
21. line interference is quite common in affected community where most of the off the air signals are relatively weak It is especially noticeable on channel 4 A single vertical bar running from the top to the bottom of the picture is the result of a reflected signal or co channel interference and is also not related to the radio station Ghosts in the TV picture are caused by reflected TV signals or by a damaged outdoor antenna system and are not related to blanketing interference from the radio station A snowy picture is usually the result of inadequate TV signal strength and is not the result of blanketing interference In some cases it may not be possible to eliminate the effects of blanketing interference to a television receiver FM radio or a tape player in a boombox or a portable stereo especially those portable stereos with plastic cases In these cases it is necessary to replace the receiver boombox or tape player with a comparable piece of equipment which is known to function satisfactorily in the vicinity of a strong signal from radio station A list of equipment known to operate without problems in the radio station blanketing interference area is shown in Exhibit 7 The information shown in Exhibit 7 was gathered nearly 10 years ago and the model numbers described in the Exhibit are no longer available However it is likely that the models now produced by the manufacturers listed in the category describing TV receivers tha
22. mance with external filtering Because of the wide variation in the performance of TV receivers AM FM Boomboxes and component stereo systems observed the original measurements the most prudent approach to purchasing new consumer home entertainment equipment for households within the the radio station blanketing contour is to make sure that a particular piece of equipment can be returned and exchanged for a different model if it is determined that the equipment is not capable of satisfactory operation even with external filtering in a residence near the the radio station transmitter Most major retail consumer electronics outlets have reasonable return policies that should allow such an exchange especially if the consumer discusses the potential interference problems with store personnel in advance of the sale Television Receivers The following television receivers have been tested and have been determined to operate normally with the addition of a Microwave Filter Company 5K V XX X or SKFM notch filter at between the antenna input connector and the cable or antenna lead in and a Fair Rite 0443164151 clip on ferrite core installed on the AC power lead Toshiba CF19C20 20 Color TV Hitachi 20MA1B 20 Color TV Samsung TTB2012 20 Color TV Panasonic 20525 20 Color The following television receivers were tested and were found to operate less than satisfactorily in the presence on the very strong FM field
23. n XX X MHz City State Page 10 of 20 4 Install clip on ferrite cores on the left and right speaker leads and on all of the speaker leads if you have surround sound or some other multi speaker system Use the same technique described above for the component connection leads Install the ferrite cores as close to the amplifier s speaker terminals as possible Figure 3A shows speaker connections using RCA connectors while figure 3B shows speakers connections using screw terminals The same techniques can be used for push in speaker terminals or any other kind of speaker terminal It is also possible to use toroid cores on the speaker leads wound the same way as those shown on the AC lead in Figure 1 5 If the interference is still present or if you need additional assistance call the radio station s Interference Assistance line at H leave a message and the radio station representative will return your call Filters and ferrite cores can be obtained by calling the same number Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 11 of 20 Installation of Coilcraft Filters and Clip on Ferrite Cores On a Telephone See Figure 4 The techniques shown below apply to both standard and cordless telephones Cordless phones do not have a handset cord so the filters shown on the handset shown in Figure 4 are not used l Install a Coilcraft TRF RJ 1 1 or K Com RF1 VHF line filter betw
24. nnect the 75 Ohm F connector on the lead in cable directly to the Microwave Filter Company 5KV XX X or SKFM XX X as shown in figure 2 b Follow steps 3c through 3d above 5 Plug the AC cord back into the wall outlet 6 Turn on the receiver and check to see if these steps have solved the interference problems 7 If the interference is still present or if you need additional assistance call the radio station s Interference Assistance line at H leave a message and the radio station representative will return your call Filters and ferrite cores can be obtained by calling the same number Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 9 of 20 Installation of Toroid and Clip on Ferrite Cores on a Component Stereo System See Figures 3A and 3B 1 Unplug the AC power cord for each component amplifier tape player CD player etc from the wall outlet 2 For each AC power cord thread the AC power cord through the center of the toroid core and slide the core up the cord to within 1 or 2 inches of the component s case Wrap the power cord around the outside of the core through the center of the core and around the outside of the ferrite core again as many times as possible with most power cords it is possible to wrap 10 or 11 turns through the toroid core Wrap the cord as tightly as possible around the core See Figure 1 for an illustration of how to wind the power
25. or FM receiver without causing a significant reduction of the other available TV or FM signals at the receiver The toroid do nut shape and clip on ferrite cores are made of a special material which blocks the energy at radio station frequency from entering the device on which they are used A combination of filters and ferrite devices is usually needed to eliminate blanketing interference in given TV FM receiver or other device Blanketing interference to TV signals from FM radio stations usually appears as a herringbone pattern of zig zag vertical lines in the TV picture or as the radio station s audio describe format if possible over the TV sound The interference usually affects channels 5 and 7 more severely than the other channels for televisions receiving signals directly off the air although channel 9 may also be affected The interference may be so severe that it completely wipes out the picture with the herringbone pattern or it may be very subtle showing up as a slight fuzziness in the picture on channel 5 or 7 It usually does not affect channels 4 11 13 20 22 or 28 Horizontal white lines moving through the picture or white sparklies running from the top to the bottom of the picture Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 2 of 20 are the result of interference from household power line noise and are not the result of blanketing from the radio station The power
26. produced by the radio station Mitsubishi CS 20101 20 Color TV 20 5 20 Color Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 19 of 20 These TV sets may perform satisfactorily with appropriate filters and ferrite cores installed at many locations within the the radio station blanketing contour however the four other TV sets listed above have been shown to operate satisfactorily under worst case conditions so they should be able to be used at any location within the the radio station blanketing contour All these TV sets were tested at the the radio station transmitter site where the measured ambient RF field was significantly higher than the fields measured in any of the households visited by the radio station personnel We did not test any smaller or larger TV s However several larger and smaller screen modes have been observed to operate well at some of the households we visited Yamaha YM 2755 27 Color Tv Toshiba CX32D60 32 Color TV Samsung TC3643C 13 Color TV Hitachi CT1385W 13 Color TV Based on these observations there is reason to believe that most of the models made by the four manufactures listed above will function well if they are provided with proper filters torroids and are provided with adequate TV signal strength about 0 dBmV either from a rooftop antenna or from the cable system TV S with screens smaller than 8 seem to come equipped with 1 8
27. rd Wrap the power cord around the outside of the corel through the center of the core and around the outside of the ferrite core again as many times as possible with most power cords it is possible to wrap 10 or 11 turns through the toroid core Wrap the cord at tightly as possible around the core See Figure 1 for an illustration of how to wind the power cord through the cord Re connect the AC power lead to the boom box and connect the AC plug into the wall outlet Test the boom box to determine if the interference has been eliminated 2 If the boom box has detachable speakers with external speaker leads install clip on ferrite cores on the speaker leads as shown in Figure 5 Install the cores as follows a Disconnect the speaker leads from the back of the boom box b Wind 2 or 3 windings of the speaker leads around one side of the open clip on ferrite core as shown in Figure 3A or Figure 3B using the slot running through the center of on side of the core as a trough to hold the cables Leave just enough of the leads at the boom box end of the cables extending out of the cores to allows the speaker leads to be connected to the boom box output connectors Close the other half of the core over the cable windings and press the two halves of the core together until the locking clips on the side of core box snaps closed d After the cores are installed on the cables coil the excess lengths of the connecting cables as sho
28. same technique described above for the component connection leads Install the ferrite cores as close to the sound card s speaker terminals as possible It is also possible to use toroid cores on the speaker leads wound the same way as those shown on the AC lead in Figure 1 6 Plug the AC cords back into the wall outlets 7 Turn on the computer and monitor and check to see if these steps have solved the interference problems Check solid single color areas of the picture for signs of herringbone interference vertical zigzag lines 8 If the interference is still present or if you need additional assistance call the radio station s Interference Assistance line at leave a message and the radio station representative will return your call Filters and ferrite cores can be obtained by calling the same number Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 18 of 20 EXHIBIT 7 TV RADIO AND TELEPHONE EQUIPMENT WHICH HAS BEEN SHOWN TO WORK IN THE AREA SUBJECT TO BLANKETING INTERFERENCE IN THE VICINITY OF THE the radio station TRANSMITTER SITE NOTE This information was gathered nearly 10 years ago and the model numbers described below are no longer available However it is likely that the models now produced by the manufacturers listed below in the category describing TV receivers that perform adequately with the addition of external filters will also provide adequate perfor
29. t RRR gt gt gt 5555521 52255225254 5 5311 318 2 ALSWd FVD INILOINNOD 440 19 37 SS39X3 193 ATHOLL ISD 53 6 2 IN3WJI3 31553 0902 wow ov QUAN 1011104465 SLY ORS 1397 IHON 1397 1331 N 83345 XAV YIAGOIY YAMIN 15 580123 5 5135 NO 3803 318533 593113 803 51 134 NOWVTIVISNI 5 NOSMVG 909 AMOJ OV NO 3409 313434 010401 LOLLLOLZ6S SL WALSAS 37892 VNN3LNY J879 0 31 ANFIWAINDA 1911 5114 19 1 85 NOS O6 WIMS NO 5 06 QIMGAH JHA SOSAN 82113 JAVMCMIIN WHO OOE 9 WHO SZ STWNINYAL 2 26 YNNALNV 0300 83904 39 ONI SONVWIddV 91 31815509 SY 35019 SY 53809 314433 NY TIVLSNI LON 3X09 314433 GIOYOL 10111022565 HIVd YOLSINNOD da WHO SZ 21872 0 31 80 VNN3LNVY NML WHO 48 INIWANOI YO 0911 81 yana 1594 MVHS OOVA LGZL GL HINNOJSNYNL 6 06 3 6 YO 6706
30. t perform adequately with the addition of external filters will also provide adequate performance with external filtering Because of the wide variation in the performance of receivers AM FM Boomboxes and component stereo systems observed the original measurements the most prudent approach to purchasing new consumer home entertainment equipment for use in households within the the radio station blanketing contour is to make sure that a particular piece of equipment can be returned and exchanged for a different model if it is determined that the equipment is not capable of satisfactory operation even with external filtering in a residence near the radio station transmitter Most major retail consumer electronics outlets have reasonable return policies that should allow such an exchange especially if the consumer discusses the potential interference problems with store personnel in advance of the sale The filters and ferrite cores shown in the attached drawings are all available from the radio station These filters and ferrite cores can be obtained by calling the Station s Interference Assistance number and leaving a voice mail message so that a representative of the radio station can return your call and arrange to provide you with these devices and with further assistance if necessary Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 3 of 20 Installation of a Notch Fil
31. ter and Ferrite Toroid Core on a TV Receiver with a 75 Ohm F Connector Antenna Input See Figure 1 1 2 Unplug the TV s AC power cord from the wall outlet Thread the AC power cord through the center of the toroid core and slide the core up the cord to within 1 or 2 inches of the TV set Wrap the power cord around the outside of the core through the center of the core and around the outside of the ferrite core again as many times as possible with most power cords it is possible to wrap 10 or 11 turns through the toroid core Wrap the cord at tightly as possible around the core See Figure 1 for an illustration of how to wind the power cord through the core Disconnect the 75 Ohm connector on the antenna or cable system lead in from the antenna input at the rear of the TV Connect the Microwave Filter Company 5KV XX X or 5KFM XX X where XX X is the station s operating frequency in MHz notch filter directly to the antenna input at the rear of the TV Connect the antenna or cable system lead in to the opposite end of the filter from the TV Make sure that the connections are tight use your fingers don t tighten them with a wrench or you may damage the threads on the connectors If you have an external antenna with 300 Ohm twinlead flat cable as the antenna lead in then there is already a 300 Ohm 75 Ohm transformer installed between the 300 Ohm cable and the 75 Ohm connector on the TV Install the
32. ting with no problems within the the radio station blanketing area There is also a similar model available from Southwestern Bell which appears to operate very well Hatfield amp Dawson Consulting Engineers YOLOINNOS VNNGINV d WHO GZ HUM 5135 NO 53809 314433 9 SHANIA AL 5 SNIMOHS 0505 30 OL 371815504 SV 15012 5 34495 314433 DIONCL TIVLSNI 0505 4 NO 3800 315533 00901 1011102285 SLY 08 5 YO SS dHyS 31899 0 31 43118 YOLOINNOD WHO SZ ONIETASNOD NOSMVG LNIANO YANA 145 138 2 YOLOANNOD 4 WHO 54 ONIETASNOD 31195 amp 9383 09 303 1139 NOUVTILSNI 8 NOSMVd X gt 9803 NO 3803 51833 91030 101 102465 ANd 06 345 GOG AMS JHA 4HN ANIA WHO 008 WHO 52 3955 VNNALNV 9805 40 OL 37815509 SV 35075 SV 53809 315333 09801 TW TIWLSNI 3LON 99905 Y3MOd JV 3803 51833 9100 LOLL 04465 divs ANJWAINDA YO 0911 517 93174 1 YOVHS oldva 06 345 6 6 5 YAWYOASNVAL ANIH
33. ulting Engineers the radio station XX X MHz City State Page 5 of 20 e Make sure that the connections to the filter are tight use your fingers don t tighten them with a wrench or you may damage the threads on the connectors 4 For TV s connected to 75 Ohm coaxial cable lead n from a rooftop antenna from the cable system a Connect the 75 Ohm connector on the lead in cable directly to the Microwave Filter Company 5KV XX X or 5 filter as shown in figure 2 b Follow steps 3c through 3e above 5 Plug the AC cord back into the wall outlet 6 Turn on the TV and check to see if these steps have solved the interference problems Check solid single color areas of the picture for signs of herringbone interference vertical zigzag lines 7 If the interference is still present or if you need additional assistance call the radio station s Interference Assistance line at H H leave a message and the radio station representative will return your call Filters and ferrite cores can be obtained by calling the same number Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 6 of 20 Installation of a Notch Filter and Ferrite Toroid Core on an FM Receiver with a 75 Ohm Connector External Antenna Input See Figure 1 Figure shows the installation of a filter on a TV set The installation of a filter on the external antenna input of an FM re
34. wn in Figure 3A or Figure 3B and use a plastic cable tie available at Radio Shack and at many hardware stores to hold the coiled cable together e Plug the speaker leads to the appropriate connectors on the boom box Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page 13 of 20 3 If the Boom box has an FM tuner try collapsing the whip antenna on the boom box to its shortest length and leaving it in the storage position usually parallel with the top of the boom box This will sometimes reduce the level of the radio station s signal entering the radio and may reduce the interference 4 If the boom box has an external antenna connector of some kind try installing an external antenna and a Microwave Filter Company 5KV XX X or SKFM XX X notch filter as described on pages 6 8 5 If the interference is still present or if you need additional assistance call the radio station s Interference Assistance line at H leave a message and the radio station representative will return your call Filters and ferrite cores they can be obtained by calling the same number 6 If all attempts to eliminate the interference fail you may have to obtain a replacement boom box A list of boom box models known to function well in the presence of a strong signal from the radio station is shown in Exhibit 7 Hatfield amp Dawson Consulting Engineers the radio station XX X MHz City State Page
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