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Emperor TS-3010 Review

This is the newest arrival from the makers of Emperor radios. It's a 4 watt AM 12 watt SSE rig. The first radio released to the US by Emperor was the TS-5010, an upgraded copy of  the President HR-2510. The new TS-3010 has the look of an updated Cobra radio. The display is LCD with a six digit display/counter. This is a unique feature, the first four digits are a direct display the same as in the HR-2510, RCI-2950 etc. and the last two digits (1KHz and 100Hz) are a frequency counter which changes as the clarifier is moved. This comes in handy finding center slot or running even frequencies on SSB, say 5Khz. down from channel 36 or 27.3600Mhz.

I'm not sure whether they were shooting for a type accepted CB or a Amateur radio. It is modifiable from the front panel. One mode is 40 channels including "A" channels. The other mode comes up in the Amateur band on 28.315Mhz. in band F. Turning the channel selector automatically runs you through the 7 bands from 25.615 Mhz. to 28-755 Mhz. In either mode it could present a problem for dealers in this country. They have a second version, not released release yet, that powers up on 10 Meters in the 28.315 Mhz to 28.755 Mhz band. This would be a legitimate 10 Meter Amateur radio. The second mode of operation has 8 bands ranging in frequency from 25.165 Mhz. to 28.755 Mhz. In both versions of the radio the channel and alternate channel mode is obtained by pressing the Meter and Tone buttons at the same time for I second. Dealers be ware! Don't openly sell this as you would a HR-2510 or any other 10 Meter rig. In it's present version you won't have a leg to stand on if Uncle Charlie visits.

This is a nice looking rig. The face of' this radio is brushed aluminum with chrome knobs and bezel. The mic connector is conveniently located in the front. All but the channel selector knob have pointers protruding beyond their edges but the pointers would be more functional if they were painted a color that would stand out from the chrome. One thing puzzles me, their placement of the front panel controls. The volume is the forth control from the left and like most operators I'm use to it being either the first or second from the left.

Inside the radio I found the quality to be very good. Immediately I noticed the clean design and absence of the usual wire harnesses. I counted a total of 18 interconnection wires including and this includes the two speaker wires. The rest of the interconnecting wiring is done through ribbon cables minimizing obstructed view of the main board. Once the covers are off the removal of the face bezel is easy and can be done without removing any more screws. All that's need is to remove the eight knobs and lift six clips while sliding the face off. The CPU board, mounted in the face of the radio, can be removed by taking out two screws and unplugging three ribbon cables. Then by sliding the CPU board up it can be removed form the series of interlocking tabs and separated form the radio. The boards are well marked with signal names and component designators. This is a real plus for technicians. I know it really helped me while I was working on it. I'm in the process of getting a service manual for the TS-3010. All the improvements I made were without a schematic and my changes may be fine tuned once I see the circuitry in it's entirety.

Bench and on air test showed the receiver AM/SSB sensitivity and selectivity is about average for this type radio. Sideband did overload on strong signals similar to the President Jackson before modification. I was able to cure this with two added component and one value change in the AGC circuit. The stability is pretty good, it only changed about 250 Hz. from cold to warm. The clarifier is locked as usual. I'm happy to say this is the first radio I've operated with a mechanical rotary encoder channel selector that couldn't be fooled. It didn't jump extra channels or change them in the, wrong direction when the channel selector was rotated very slowly or quickly. The transmitter has clean audio on both AM and Sideband before and after peaking.

There is a drawback on this display/frequency counter. The third digit doesn't change when, you go up 5Khz. If you're on 27.4050 and go up 5Khz. the display will read 27.4000 not 27.4100. If you run on even frequencies you'll just need to keep that in mind. I tried to get the radio to drop 5KHz. This would have solved the display problem but it didn't work out.

Despite the problems I've uncovered the TS-3010 is a good radio. For the cost of a Uniden Grant XL with channels you can have the Emperor with a six digit display/counter and 3 times the channels. I wish they made provisions in the CPU for 5Khz channel steps. It would have been easy because the rig uses a PLL0305A chip which can be stepped in as low as 100Hz increments. The rig is setup for a UP/DOWN mic but the stock mic is a very small dynamic type with no room for buttons. The HR-2510 mic, has the. same wiring and the UP/DN buttons will change the channels without changing anything. An Astatic 575M6 works dynamite and there is room for UP/DN push button switches. Also a battery back-up is used to retain the last frequency used. The radio is well made and is the best sideband radio in the $240 price range with these features. I hope the factory addresses the problems I've found and comes out with a 5Khz. channel step version of this rig. If they do this I'm sure this will become the #1 radio in sales.

The following are changes that I made to the Emperor TS-3010:

©^CBWI

PUBLICATION #31A
BULKHEAD GROUNDING FOR TELECOMMUNICATIONS FACILITIES

Most telecommunications facilities in the Land Mobile Services, Broadcast, Amateur and Personal Services are woefully under-grounded. Each year insurance companies pay out thousands in claims for lightning damage to installations that are "fully lightning protected". When inspecting these facilities it's easy to see why lightning damage so easily caused, or why the station suffers from high, noise levels and lots of interference.

Proper grounding is almost always the culprit, and it is so often the result of the ground system being installed as a quick , cheap afterthought to radio equipment placement. A really good engineer knows that the first item, designed, constructed, and installed in a telecommunication facility is the ground system. And of the many ways that a grounding system can be employed, one type stands out as most often the best performer. Better yet, it costs less to build, involves less materials, and takes less time to implement.

Bulkhead ground systems are very easy to understand. They consist only of a place and a single metallic fixture. The bulkhead is most often a metal plate made from aluminum but almost any metal will do just fine. A bulkhead could also be a piece of heavy wire several feet long to which station cables and protective devices are attached. It's not what you have, It's what you do with what you have. Most installations consist of an outside antenna with a coaxial line downlead connected to bonded equipment frames, and then a wire running from that point to ground. This has the unfortunate effect of placing the equipment Chassis (and the operator if he is there) in series with an incoming lightning surge, nearly always causing equipment damage and often injuring the operator. A bulkhead grounding system overcomes this deficiency by intercepting the incoming surges and shunting them to ground BEFORE they reach the equipment.

A bulkhead plate is defined as a high integrity, zero or low inductance earth terminal connection. For that reason a bulkhead plate should always be placed very close to or on the ground with its lead connections to earth entry point very short - preferably less than a foot long. All incoming lines to the facility (coaxial cable, rotor lines, control lines, AC power lines, telephone lines, etc.) pass across the plate where they are connected to various lightning protective devices. The radio equipment should be located close by to take advantage of short distance grounding to the bulkhead plate, thus reducing or preventing harmful local interference in transmission and reception. No other grounds should be employed or lightning current division may occur if the facility is struck. Division is what causes induced currents to flow across equipment chassis, resulting in circuitry damage.

What makes a good bulkhead? A commercial rely rack panel of 1/8" thick aluminum is quite nice and easy to obtain through electronic distributors. Copper plate is ideal if available, but even a steel plate is acceptable. Mount antenna switches, transmitting and receiving filters, and lightning protective devices all on the same plate, and be sure to use an anti-oxidant between metal surfaces to ensure good long term metal-to-metal electrical bonding. Examples of good anti-oxidants are Burndy Penetrox, Ideal Noalox, or I.C.E. Model 601 or 602. Mounting the bulkhead indoors against an exterior wall is suggested so that access may be obtained and protection from weather is assured. Keep all leads short and connections tight. And try to obtain a plate that is bigger than what you expect to need so that some room is left for facility expansion. Once you find out how nice the bulkhead system works, you'll probably want to build a bigger station. ©^CBWI

TECHNICAL PUBLICATION #36
GROUNDING COAXIAL CABLE SHIELDS: WHY, WHERE, AND HOW

Even today it's a controversial subject - but we don't know why. The purpose and importance of grounding coaxial line shields is so critical to safe and clean telecommunication station operation that it should not be a matter of discussion, except as a how-to subject such as this paper represents.

Coaxial cable used in radio and television work is referred to as unbalanced line primarily because the center conductor carries the current and signal voltage nearly all to itself. The shield of the transmission line is just that - a shield. It carries no current except for a small induced current flowing as the result of induction by length. In a perfectly matched system the current in the shield is almost nil. That's also why in most modern applications coaxial cable shields are fitted to connectors without soldering - only compression fitting. Center conductors carry the current during transmission so they are generally soldered in place.

But that doesn't mean that the shield has no work to do, and that's the purpose of this brief technical narrative. Coaxial shields provide a protection for the center conductor and prevent ground level line leakage during transmission, noise pickup from external local sources during reception, continuous impedance matching, and physical rigidity to the line.

Short distance grounding of coaxial shields introduces an earthen neutral integrity to the shield and provides a drain source for the very types of disturbances the shield is designed to resist. It's very common to hear of stories relating how interference to other services disappeared or reception noise was reduced when shield grounding was accomplished. In lightning protection applications the shield is an exposed element, and when lightning strikes overhead or a direct "hit' occurs to antennas and tower frames it's not unusual to find as much as 80% of the applied current seeking ground through the transmission line flows down the shield. If the lightning currents do not find earth through a dissipation point before reaching the radio equipment chassis then damage to the station gear will nearly always result. In severe cases injury or loss of structure can occur.

Grounding of shields is easy and requires little experience or effort. The connections for grounding should always be done at ground level if maximum value is to be obtained, and the lead length from shield to earth entry point (the dirt) should be kept as short as possible - less than a foot if possible. Using a commercial grounding block is a very neat way of accomplishing the task, but making your own shield connections can, be done as well. Cutting the cable, inserting connectors and grounding the shield by attachment to the connectors is a common method but suffers from the inevitable impedance "bump" in the line at that point and the possibility of exposure to water or contaminants. Removing the outer plastic with a sharp knife carefully, wrapping a solid copper wire around the exposed shield and then grounding the wire is another method that seems to work well and doesn't leave an impedance irregularity in the line.

However the work is done is far less important than making sure it gets done, and establishing a common point for multiple shield grounding makes sense in stations that use many different transmission lines. But the most important element is to be sure that the coaxial cable lines are ALWAYS brought to the ground surface first, and that shield grounding, is accomplished at that point BEFORE the cable continues on its way to reach station equipment. Keep the connections clean, tight, and waterproof - then relax and enjoy the benefits of your efforts! ©^CBWI

TECHNICAL PUBLICATION #60
USING ANTI-OXIDANTS TO ENSURE GOOD CONDUCTIVITY

Anti-oxident compounds are not a new invention or idea in the pursuit of good integrity or longevity of joint connections that make up telecommunication facilities. But their use has been popularized and improved in recent years with the advent of synthetic lubricants with wide temperature capacities and improved lubricity. Many important connections in radio and television work can be easily compromised overtime by water condensation and vaporous atmospheric chemicals. When dissimilar metals are used in direct contact the effect can occur faster and with greater severity, especially outdoors. Examples of common trouble areas are ground terminal connections, radial system connections, RF connections, and even the bolted joints between stacked tower sections.

There is nothing inherently wrong with using dissimilar metals in direct contact. But if the joint is exposed to air, or if the joint commonly passes a great amount of current then the oxidation that occurs in the metals will accelerate and eventually the connection will fail. It may even heat to a point where the metals melt or burn.

An anti-oxidant performs two critical functions. First, the anti-oxidant compound material placed in the region between the two metal conductors seals out air and moisture. The use of synthetic lubricants in the base compound ensures that the material is not miscible with water or other chemicals and cannot be driven out. The second function is that modem anti-oxidants are electrically conductive under pressure. This is accomplished by mixing copper, aluminum, lead, and/or graphite flakes in the 5-10 micron range into the lubricant vehicle and then applying the compound to the surfaces to be joined. The addition of metal particles into the mixture also creates a heavy compound which is more difficult to displace by weatherization.

The application of anti-oxidants is simple and easy. Both the metal surfaces to be joined should be cleaned and then either brushed with a wire wheel or emery paper. The ridges cut into the metals in this process are actually beneficial, and the scraping also ensures that bare metal is reached before anti-oxidants are applied. The compound may then be applied by any convenient means (brush or finger). Work the material around a small amount and don't be afraid to use the compound in a liberal manner. Remember that filling the air voids in the contact joint is a critical necessity. Any extra compound will squirt out the side when the metals are joined together, and it's easy to scoop up the excess and push it back into the original container for later use.

The next step is tighten, tighten, tighten. Make sure the joint connections are plenty tight and that hardware will not back out in use. A weather covering is a good idea to help prevent external corrosion and to help keep hardware from moving. Washing down the outside of the joint with alcohol will drive off any excess anti-oxidant compound.

Use different compounds for different types of jobs. For copper-to-copper or copper-to steel joints use a copper-loaded anti-oxidant such as our Model 601 Series. For aluminum-to aluminum or aluminum-to copper use a complex compound such as our Model 602 Series.

Anti-oxidants have no rated shelf life so they may be stored in virtually any location or condition. Just be sure to stir the mixture before use to assure good mixing suspension of the metal flakes inside.

Sensible use of these compounds offer a high degree of reliability and long term satisfaction to users who want serious results in telecommunications work. ©^CBWI

TECHNICAL PUBLICATION #30
MODERN LIGHTNING PROTECTION FOR RADIO FACILITIES: RF ENTRY PORTS

Lightning is one of Nature's most destructive forces. It has the power of a good sized explosive and cannot be avoided if you're connected to antennas that are high and in the clear. And it's not just lightning. On a recent evening our 160 Meter dipole (260 foot wire span) strung between towers at 180' here at the I.C.E. Factory exhibited several hundred volts of charge from a light rain shower - enough to shock one of the technicians working with the cable outside. During an electrical storm with overhead discharges many thousands of volts have been measured on this wire, respective to earth.

In installations using coaxial feedlines the measures used to protect station equipment are simple but critically important. Here is a list of observations and our recommendations in the strongest possible terms .....

1) Always bring coaxial cables to ground level before entering equipment area. Never bring coaxial cables into the building at an elevated height directly. Lightning currents induced into the cables will be forced throughout the equipment chassis on their way to ground, and that's what causes extensive damage. Even if your equipment is on the second floor, always bring coax to ground level first and insert appropriate lightning protection, then route the cable to the station.

2) Absolutely, absolutely, positively, positively ground those shields with as short an earth terminal connection as possible. Use a commercial shield grounding block is possible, or fashion your own. In most cases as much as 80% of an induced or direct lightning blast comes in on the shield. This is because of the external exposed nature of the shield and its larger metallic mass. Always make sure that grounding the shields occurs BEFORE the cable enters the building. Multiple shield grounding (such as once at the tower base and again before building entry) is an excellent idea.

3) Use lightning arrestors on lines that feed sensitive electronics. But beware. Don't use so-called lightning arrestors that employ nothing more than a gas-discharge device to ground. These units are DC passive and only activate when the potential voltage between conductors reaches hundreds of volts. By that time in most cases the radio has already been damaged before the arrestor kicks in, leaving you with an arrestor that did mostly nothing and a damaged rig. Additionally, gas discharge tubes are very low power, typically only around 1 watt dissipation. They're rated for 20,000 amps or more, but only if a lightning blasts starts and ends in a few billionths of a second. Few bolts ever do, and bolts that are slowed down coming through transmission lines almost never do. That's why gas discharge arrestors require repair and replacement so often. They're overpriced and offer little, if any, protection from induced voltages.

If lightning. arrestors are used always specify a blocking type arrestor - that is, a unit that has no DC continuity through from input port to output port. And one that offers constant drain mechanism with no pre-determined turn-on voltage has enormous power handling capacity, far exceeding the units that rely solely on gas discharge tubes or varistor devices. 

4) Establish a grounding. bulkhead near the radio equipment where the distance from the bulkhead to the soil entry is short - preferably less than a, foot. Use this bulkhead for lightning protection as well as RF neutral for interference filters and similar items. The bulkhead can be a bar, metal sheet, or just heavy wire. Remember - the length of ground leads is far more significant to good grounding performance than the specific materials or even wire size used. Keep 'em short! ©^CBWI

TECHNICAL PUBLICATION #30A
MODERN LIGHTNING PROTECTION FOR RADIO FACILITIES: AC POWER LINES

Lightning damage to electronic equipment caused by induction or direct hit and traveling along AC power lines is the most frequent port of entry in modem telecommunication systems. It's not uncommon to find facilities that have extensive lightning protective devices on RF transmission lines and telephone lines but have little or no AC line protection. It is possibly because AC line service protection is less understood, but more likely because there are few products available. commercially that offer really sound protection.

The reason that AC power delivery is such a common entry source is easy to see. Power lines are heavily exposed, usually for many miles from the equipment site. They are often strung overhead, sometimes hundreds of feet high. A single lightning blast to exposed power lines can travel for miles looking for distribution means to reach earth ground. In its path the surge will divide among many low resistance points, usually damaging all of them. Virtually anything connected to AC power is subject to surge distribution, and delicate solid state electronics are normally the first items damaged.

Yet protecting AC lines is relatively easy compared to other types of entry ports. But the only truly effective method of achieving good protection is at the service entrance of AC power to the structure where electronic equipment is housed. In modern applications popular plug-in type devices sold in hardware stores offer poor, if any, protection. The reason is that they are located far from actual earth ground in most cases, and they often have voltage breakdowns so high that by the time the device begins to work the damage has already been done.

Structural type protectors offer unique advantages. First, because they are located at the service entrance they protect nearly all AC operated items in the building. The units activate on incoming high voltage AC or DC wavefronts, stopping them in the line of travel before they enter the building's AC wiring distribution system. Second, service entrance panels are most often located in a place where local earth terminal ground connections are nearby, so short leads of heavy wire are both possible and frequently installed by electricians when the service box is mounted.

A structural protector is designed for large incoming voltage surges of very high power. The better units offer hybrid action, which means that they employ two different methods of voltage attack and power handling capability. Normally the two internal systems employed are Metal Oxide Varistor (MOV) technology and Gas Discharge (GDU). MOVs are particularly useful because they feature fast attack to overvoltage surges, dual polarity operation, relatively high power handling capacity if paralleled and are inexpensive. Gas discharge units offer even faster attack times, higher power handling capacity per unit and dual polarity operation but at somewhat higher cost. The use of GDUs are also a bit sensitive in the design stage because they go short when activated, possibly rupturing or not extinguishing properly in AC line service. There use must be carefully figured.

A combination of the two types offer the best performance, and a unit can be tailored to slope the attack mechanism so that the device can safely handle both small wavefronts and the inevitable large ones. MOV devices installed in equipment cabinets is also a good idea, especially if the equipment is located 100 feet or more from the service panel entrance. Another feature of MOV devices, no matter where they are located, is that they have large distributed capacitance in the structure of the device, offering some RFI protection as well.

Don't forget to connect the ac service neutral ground to the facility's grounding bulkhead system for wider lightning current distribution. ©^CBWI

TECHNICAL PUBLICATION #30B
MODERN LIGHTNING PROTECTION FOR RADIO FACILITIES: CONTROL LINES

Most communication facilities have a variety of unshielded control line wires used for antenna switching, sensor monitoring, antenna rotation, telephone service delivery, or other local functions. While these lines are a necessary part of the overall station design, they also complicate matters from a lightning perspective because they. offer multiple entry ports for large and potentially damaging EMP currents during storms. The same lines also couple into transmitted RF energy and often re-radiate the signal at ground level where interference is likely to occur.

Protection from both of these possible ailments is a necessity in modem facility design, and the best way to achieve such protection is in the station's bulkhead grounding system. Both protective and bypass devices can be easily fitted into the scheme if the lead length from the connection point to earth ground is kept short. The length of attached leads running to ground is far more important than the specific material used for the connections, but heavy copper wire in the size range of #12 or larger is recommended.

Here are a few reminders when feeding station equipment with control lines....

1) Make a map of the entire control line layout to assure that no lines are missed when designing protection schemes. Include the estimated length of lines between destinations and include overvoltage protection and bypass devices for any lines exceeding about 25 feet. Make the map in pencil so changes can be made easily and date the map for future reference.

2) Try to keep control lines bundled together where possible but group them separately from RF transmitting coaxial lines. Coupling of RF signals into control lines can be severe if they are bundled together and run considerable distance due to coax cable shield leakage. It's best to run RF lines up one tower leg and attach control lines to another tower leg to help decouple the two.

3) The use of lumped inductance in control line leads is generally a good idea. An inductor should have the same wire size as is being used for the lead and a measured inductance of 100uh or greater should be used. The effect from inductance in lightning protection is that it slows down the incoming wavefront from the reactance of the coil presented to the incoming wave risetime. In RF interference it acts like an RF choke to help stop re-radiation of signals. Bypass both sides of the choke for additional RF decoupling with capacitors rated to 1,000V or greater.

4) Installing rotator/control line protection devices (such as our Models 348 or 349) provide an excellent method of shunting overvoltages to a grounding bulkhead termination. Always try to shunt all lines to a single bulkhead point close to where the connected equipment is located. If the station is elevated (2nd floor or higher) always bring lines to ground level first for the installation of protective and bypass devices, then route the cables upward to the equipment chassis in series with any incoming lightning currents, possibly causing both damage and injury if you're hit.

5) If you're able to install control line runs in conduit or buried plastic pipe it's generally a good idea. Not only does the pipe protect cables from weather but they are also protected from small animals (who like to chew on them) and the appearance of the facility improves! ©^CBWI

TECHNICAL PUBLICATION #33
MODERN COAXIAL LIGHTNING ARRESTORS: POLYPHASER VS. I.C.E.

This is a comparison report between coaxial cable lightning arrestor units manufactured by Polyphaser Corp. and Industrial Communication Engineers, Ltd. Both companies manufacture a wide variety of such protective devices and are sold worldwide. Each of the designs described in this report is protected. by patents issued by the U.S.- Bureau of Patents and Trademarks in Washington, D.C.

Although - there, are . some subtle variations. in, the product line, Polyphaser's basic coaxial line layout is. basically a two component system. As shown in the schematic below, a high-voltage rated capacitor is used as a central blocking device to permit the unimpeded flow of RF currents through the arrestor while blocking DC voltages and low frequency AC voltages from passing through the arrestor while blocking DC voltages and low frequency AC voltages from passing through the device to reach station equipment. A gas discharge assembly having a breakdown voltage rating in the 400-1,000 volt range is used for transmitting services so that when a difference of potential between the conductors reaches this amount on the antenna side of the polarized unit the gas discharge unit ignites, shunting the voltage surge to ground.

While this is certainly a workable arrangement and the Polyphaser units are well built, we concluded in our engineering studies that there were significant limitations to the design. Among them:

1) No constant drain mechanism is provided in the Polyphaser design. A coaxial line acts often like a large capacitor, storing electrical charge that can only leak off the line through antenna joint connections or through the dielectric, nearly always causing receiver "hash" noise during electrical activity.

2) The use of a gas discharge unit as a sole-source mechanism for neutralizing lightning currents delivered by heavy coaxial line conductors is controversial. Gas units have only a small dissipative power rating, seldom exceeding 1 watt. While the devices can handle large jolts of thousands of amperes of current, they can perform that service only if the entire impact event lasts only a few microseconds. Lightning currents, especially slowed down by time constants due to the inductance of transmission lines are much slower to begin, endure, and end. The result is rupture and failure of gas discharge units, requiring frequent replacement and down time.

3) It is very difficult to determine the condition of a gas discharge unit, especially after it has taken a few "hits." They don't always go short circuit.

The I.C.E. design, also shown below, took these characteristics into account during development and testing. We also use a central high voltage blocking capacitor, but with a large discharge inductor on the antenna side as a primary neutralizing agent. Any voltage development is quickly shunted to ground through the DC shorting nature of the inductor/RF choke. If large currents of a fast rising nature,, are presented to the arrestor in such a way that a back-EMF develops across the inductor then the companion paralleled gas discharge unit ignites, but its only workload is to collapse the magnetic field of the inductor. The result is an arrestor whose gas unit undertakes such a low workload that is will probably last forever. To date no replacement gas units have been sold by us. The added resistance on the equipment side of the arrestor was inserted to provide a similar drain function on the user side of the arrestor. I.C.E. uses a four part system. ©^CBWI

TECHNICAL PUBLICATION #33A
MODERN COAXIAL LIGHTNING ARRESTORS: ALPHA DELTA VS. I.C.E.

This is a comparison report between coaxial lightning arrestor units manufactured by Alpha Delta Corp. and Industrial Communication Engineers, Ltd. Both companies make a variety of such protective devices and are sold worldwide. The I.C.E. design described in this report is protected by a patent issued by the U.S. Bureau of Patents and Trademarks in Washington, D.C.,

Alpha Delta's primary configuration is a one part system consisting of a gas discharge breakdown unit connected in a shielded enclosure between the coaxial center conductor and an insulated, external ground terminal fitting protruding through the case. The gas discharge unit (GDU) has a rated breakdown voltage in the 400-1000 volt range to allow the transmission of an-RF waveform through the unit without creating a sufficient voltage potential referenced to ground to ignite the conductor referenced to ground the gas unit ignites, creating a temporary low resistance path to ground, thus neutralizing the potential.

While this arrangement may be suitable protection in a few cases it suffers from numerous limitations that we believe to be serious. Among them:

1) The case of the unit that is connected to the coaxial cable outer conductor passes throughout the unit and no provision is made for grounding the case directly to earth ground. In lightning strike applications, both direct hits and indirectly (inductively) coupled events, measurement studies have shown that as much as 80% of the incoming surge flows down the exposed shield of the cable. The unfortunate result is that a large amount of the strike simply passes across the arrestor chassis and reaches station equipment frames, dividing between many destructive paths seeking ground.

2) The unit uses a pass-through center conductor. Although the gas discharge assembly will ignite when the breakdown potential is reached many hundreds of volts are presented to the input of the radio equipment before the arrestor action occurs. In modem solid state terms it means that the radio will nearly always be damaged or destroyed before the arrestor activates to neutralize the income electromagnetic wavefront.

3) The use of a gas discharge unit as a sole-source mechanism for neutralizing lightning currents delivered by heavy coaxial cable line conductors is controversial. Gas units have only a small dissipative power rating, seldom exceeding, I watt. While the devices can handle large jolts of thousands of amperes of current, they can perform that service only if the entire impact event lasts only a few microseconds. Lightning currents, especially slowed down by time constants due to the inductance of transmission line conductors are much slower to rise, endure, and dissipate. The result is frequent rupture and failure of the GDU, requiring down time and parts replacement. Additionally, it's difficult to determine the condition of a GDU in service, notably after they have taken a few suspected "hits." They don't always go short circuit, but they sometimes fracture and separate.

4) No constant drain method is employed to leak static development from cables. A coaxial line often acts like a large capacitor, storing electrical charge which can only leak off the line through antenna joint connections or through the insulated dielectric region between the conductors. When this occurs it nearly always causes receiver "hash" noise during electrical activity.

The I.C.E. design, shown below on the right side, took these characteristics into account during development and testing. Our arrangement uses a central high voltage rated blocking capacitor which allows the free flow of RF energy through the arrestor device but blocks DC voltage and low frequency AC voltage. The heavy inductor on the antenna side of the unit is the primary neutralizing agent. Voltage development is quickly shunted to ground through the DC shorting nature of the inductor/RF choke. If large currents of a fast-rising nature are presented to the arrestor in such a way that a back-EMF develops across the inductor then the companion paralleled gas discharge unit ignites, but its only workload is to collapse the short-lived magnetic field of the inductor., The result is an arrestor that is constantly active, requires no predetermined voltage to activate, and whose GDU workload is so low that is will probably last forever. To date not a single replacement gas unit has been sold by us. The added resistance on the equipment side of the arrestor was inserted to provide a similar drain function on the user side of the arrestor, shunting away tiny currents that may appear from capacitor dielectric leakage during an impact event.

Schematic diagrams of the two designs appear below: ©^CBWI

TECHNICAL PUBLICATION #33B
MODERN COAXIAL LIGHTNING ARRESTORS: CUSHCRAFT VS I.C.E.

This is a comparison report between coaxial lightning arrestor units manufactured by Cushcraft Corp. and Industrial Communication Engineers, Ltd. Both companies make a variety of such protective devices and are sold worldwide. The Cushcraft "Blitz Bug" design and the I.C.E. design are both protected by patents issued by the U.S. Bureau of Patents and Trademarks in Washington, D.C.

Cushcraft manufactures two different arrestor units that are basically the same principle but utilize different methods. The first and most basic is the "Blitz Bug" patented by Mr. Cushman around 1960. In this device both outer coaxial conductor (shield) and center conductor pass directly through the unit. Three metal fastener screws are drilled and tapped into the outer metallic conductor and driven in to a close proximity to the center conductor. With the outer conductor at ground connection potential a voltage spike exceeding about 1,500 volts that develops between the center conductor and ground arcs across the space between the center conductor and the tips of the embedded screws. There are no other parts in the unit.

The second and more modern unit uses nearly the same philosophy but uses a gas discharge assembly between the center conductor and an external insulated ground terminal fitting protruding through the case. The gas discharge unit (GDU) has a rated breakdown voltage in the 400-1000 volt range to permit the transmission of an RF voltage waveform through the unit without creating a sufficient voltage potential referenced to ground to ignite the device. When a voltage greater than the breakdown voltage of the GDU appears across the center conductor referenced to ground the gas unit ignites, creating a temporary low resistance path to ground, thus neutralizing the potential.

While these arrangements may offer suitable protection in a few cases they both suffer from numerous limitations that we believe to be serious. Among them:

1) The case of the more modem unit that is connected to the coaxial cable outer conductor passes across the unit and m provision is made for grounding the case directly to earth neutral. In lightning strike applications of both direct hits and indirectly (inductively) coupled events various measurement studies have shown that as much as 80% of the incoming surge flows down the shield of the cable. The unfortunate result is that a large amount of the strike simply passes across the arrestor chassis and reaches station equipment frames, dividing between many destructive paths seeking ground. 'Me case of the earlier "Blitz Bug" design encourages connection of the shield conductor to ground, even providing a terminal to do so.

2) Both units use pass-through center conductors. Although the gas discharge assembly and the arc gap (Blitz Bug) both ignite when their respective breakdown voltages are reached many hundreds or thousands of volts are presented to the radio equipment before the arrestor action occurs. In either case when used with solid state radio gear it means that the equipment will nearly always be damaged or destroyed before the arrestor activates to neutralize the incoming surge wavefront.

3) Use of gas discharge units or arc screws as a sole-source mechanism for neutralizing lightning currents delivered by heavy coaxial cable line conductors is controversial. Gas units have only a small dissipative power rating, seldom exceeding 1 watt. While the devices can handle large jolts of thousands of amperes of current, they can perform that service only if the entire impact event lasts only a few microseconds. Lighting currents, especially slowed down by time constants due to the inductance of transmission line conductors are much slower to rise, endure, and dissipate. The result is frequent rupture and failure of the GDU, requiring down time and parts replacement. In the case of arc screws each "hit" causes some of the screw tip to be burned away so that the next jolt must be even larger to start an arc.

Additionally, it is difficult to determine in either case the actual condition of a GDU or the arc screws in actual field service after they have been used for a time. GDUs often fracture and break apart while arc screws scar and often weld themselves to the case. In both cases it is assumed, of course, that the internal resistance of the radio equipment that can take input jolts of the magnitude and service without damage or destruction.

4) In both designs m constant drain method is employed to leak static development from cables. A coaxial line often acts like a large capacitor, storing an electrical charge that can only leak off the line through antenna joint connections or through the insulated dielectric region between the conductors. When this occurs it nearly always causes receiver "hash" noise during electrical activity.

The I.C.E. design, shown below on the right side, took these characteristics into account during development and testing. Our arrangement uses a central high voltage rated blocking capacitor which allows the free flow of RF energy through the arrestor device but blocks DC voltage and low frequency AC voltage. The heavy inductor on the antenna side of the unit is the primary neutralizing agent. Voltage development is quickly shunted to ground through the DC shorting nature of the inductor/RF choke. If large currents of a fast-rising nature are presented to the arrestor in such a way that a back- MF develops across the inductor then the companion paralleled gas discharge unit ignites, but its only workload is to collapse the short-lived magnetic field of the inductor. The result is an arrestor that is constantly active, requires non pre- determined voltage to activate, and whose GDU workload is so low that it will probably last forever. The added resistance on the equipment side of the arrestor was inserted to provide a similar drain function on the user side, shunting away tiny currents that may appear from capacitor dielectric leakage during an impact event.

Schematics for all three are below: ©^CBWI